Publications by authors named "Philipp Forkel"

28 Publications

  • Page 1 of 1

Suspension button constructs restore posterior knee laxity in solid tibial avulsion of the posterior cruciate ligament.

Knee Surg Sports Traumatol Arthrosc 2021 Mar 6. Epub 2021 Mar 6.

Department of Sports Orthopaedic Medicine, Klinikum Rechts Der Isar, TU Munich, Ismaninger Str. 22, 81675, München, Germany.

Purpose: Dislocated tibial avulsions of the posterior cruciate ligament (PCL) require surgical intervention. Several arthroscopic strategies are options to fix the fragment and restore posterior laxity, including two types of suspension button devices: adjustable (self-locking) and rigid knotted systems. Our hypothesis was that a rigid knotted button construct has superior biomechanical properties regarding laxity restoration compared with an adjustable system. Both techniques were compared with standard screw fixation and the native PCL.

Methods: Sixty porcine knees were dissected. The constructs were tested for elongation, stiffness, yield force, load to failure force, and failure mode in a material testing machine. Group N (native, intact PCL) was used as a control group. In group DB (Dogbone™), TR (Tightrope™), and S (screw), a standardized block osteotomy with the osteotomized fragment attached to the PCL was set. The DB and TR groups simulated using a suspension button system with either a rigid knotted (DB) or adjustable system (TR). These groups were compared to a screw technique (S) simulating antegrade screw fixation from posterior.

Results: Comparing the different techniques (DB, TR, S), no significant elongation was detected; all techniques achieved a sufficient posterior laxity restoration. Significant elongation in the DB and TR group was detected compared with the native PCL (N). In contrast, screw fixation did not lead to significant elongation. The stiffness, yield load, and load to failure force did not differ significantly between the techniques. None of the techniques reached the same level of yield load and load to failure force as the intact state.

Conclusion: Arthroscopic suspension button techniques sufficiently restore the posterior laxity and gain a comparable construct strength as an open antegrade screw fixation.
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http://dx.doi.org/10.1007/s00167-021-06510-1DOI Listing
March 2021

Dislocated hinge fractures are associated with malunion after lateral closing wedge distal femoral osteotomy.

Knee Surg Sports Traumatol Arthrosc 2021 Feb 27. Epub 2021 Feb 27.

Department of Orthopedic Sports Medicine, Klinikum Rechts der Isar, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.

Purpose: To evaluate the incidence, morphology, and associated complications of medial cortical hinge fractures after lateral closing wedge distal femoral osteotomy (LCW-DFO) for varus malalignment and to identify constitutional and technical factors predisposing for hinge fracture and consecutive complications.

Methods: Seventy-nine consecutive patients with a mean age of 47 ± 12 years who underwent LCW-DFO for symptomatic varus malalignment at the authors' institution between 01/2007 and 03/2018 with a minimum of 2-year postoperative time interval were enrolled in this retrospective observational study. Demographic and surgical data were collected. Measurements evaluating the osteotomy cut (length, wedge height, hinge angle) and the location of the hinge (craniocaudal and mediolateral orientation, relation to the adductor tubercle) were conducted on postoperative anterior-posterior knee radiographs and the incidence and morphology of medial cortical hinge fractures was assessed. A risk factor analysis of constitutional and technical factors predisposing for the incidence of a medial cortical hinge fracture and consecutive complications was conducted.

Results: The incidence of medial cortical hinge fractures was 48%. The most frequent morphological type was an extension fracture type (68%), followed by a proximal (21%) and distal fracture type (11%). An increased length of the osteotomy in mm (53.1 ± 10.9 vs. 57.7 ± 9.6; p = 0.049), an increased height of the excised wedge in mm (6.5 ± 1.9 vs. 7.9 ± 3; p = 0.040) as well as a hinge location in the medial sector of an established sector grid (p = 0.049) were shown to significantly predispose for the incidence of a medial cortical hinge fracture. The incidence of malunion after hinge fracture (14%) was significantly increased after mediolateral dislocation of the medial cortical bone > 2 mm (p < 0.05).

Conclusion: Medial cortical hinge fractures after LCW-DFO are a common finding. An increased risk of sustaining a hinge fracture has to be expected with increasing osteotomy wedge height and a hinge position close to the medial cortex. Furthermore, dislocation of a medial hinge fracture > 2 mm was associated with malunion and should, therefore, be avoided.

Level Of Evidence: Prognostic study; Level IV.
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http://dx.doi.org/10.1007/s00167-021-06466-2DOI Listing
February 2021

A hinge position distal to the adductor tubercle minimizes the risk of hinge fractures in lateral open wedge distal femoral osteotomy.

Knee Surg Sports Traumatol Arthrosc 2020 Aug 24. Epub 2020 Aug 24.

Department for Orthopedic Sports Medicine, Klinikum Rechts Der Isar, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.

Purpose: To evaluate the incidence and morphology of medial cortical hinge fractures in lateral open wedge distal femoral osteotomy (LOW-DFO) and to determine a safe zone for the position of the osteotomy hinge to minimize the risk of hinge fractures.

Methods: Consecutive patients who underwent LOW-DFO for symptomatic valgus malalignment were screened for eligibility for this retrospective observational cohort study. Demographical and surgical data were collected. The incidence and morphology of medial cortical hinge fractures were evaluated on standard postoperative anterior-posterior knee radiographs. Comprehensive measurements evaluating the osteotomy gap and the position of the osteotomy hinge were taken. Additionally, each osteotomy hinge was assigned to a corresponding sector of a proposed five-sector grid of the distal medial femur.

Results: A total of 100 patients (60% female) with a mean age of 31 ± 13 years were included. The overall incidence of medial cortical hinge fractures was 46% and three distinct fracture types were identified. The most frequently observed fracture type was extension of the osteotomy gap (76%), followed by a proximal (20%) and distal (4%) course of the fracture line in relation to the hinge. Group comparison (hinge fracture vs. no hinge fracture) showed statistically significant higher values for the height of the osteotomy gap (p = 0.001), the wedge angle (p = 0.036), and the vertical distance between the hinge and the proximal margin of the adductor tubercle (AT; p = 0.002) in the hinge fracture group. Furthermore, a significantly lower horizontal distance between the hinge and the medial cortical bone (p = 0.036) was observed in the hinge fracture group. A statistically significant higher incidence of medial cortical hinge fractures was observed when the position of the osteotomy hinge was proximal compared to distal to the proximal margin of the AT (53% vs. 27%; p = 0.023).

Conclusion: Medial cortical hinge fractures in LOW-DFO are a common finding with three distinct fracture types. To minimize the risk of medial cortical hinge fractures, it is recommended to aim for a position of the osteotomy hinge at the level of or distal to the proximal margin of the adductor tubercle.

Level Of Evidence: Prognostic study; Level III.
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http://dx.doi.org/10.1007/s00167-020-06244-6DOI Listing
August 2020

Isolated high tibial osteotomy is appropriate in less than two-thirds of varus knees if excessive overcorrection of the medial proximal tibial angle should be avoided.

Knee Surg Sports Traumatol Arthrosc 2020 Jul 20. Epub 2020 Jul 20.

Department for Orthopedic Sports Medicine, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.

Purpose: To perform a detailed deformity analysis of patients with varus alignment and to define the ideal osteotomy level (tibial vs. femoral vs. double level) to avoid an oblique joint line.

Methods: A total of 303 digital full-leg standing radiographs of patients aged 18-60 years and varus alignment [mechanical tibiofemoral varus angle (mFTA) ≥ 3°] were included. All legs were analyzed regarding mFTA, mechanical medial proximal tibia angle (mMPTA), mechanical lateral distal femur angle (mLDFA), and joint line convergence angle. Based on mFTA, varus alignment was categorized as "mild" (3°-5°), "moderate" (6°-8°), or "severe" (≥ 9°). Deformity location was determined according to the malalignment test described by Paley. Two osteotomy simulations were performed with different upper limits for mMPTA: anatomic correction (mMPTA ≤ 90°, mLDFA ≥ 85°) and overcorrection (mMPTA ≤ 95°, mLDFA ≥ 85°). If a single osteotomy exceeded these limits at the intended mFTA of 2° valgus, a double-level osteotomy was simulated. If even a double-level osteotomy resulted in deviations from the defined limits, the leg was categorized as "uncorrectable".

Results: Mean mFTA was 6° ± 11° of varus (range 3°-15°). A tibial deformity was observed in 28%, a femoral deformity in 23%, a combined tibial and femoral deformity in 4%, and no bony deformity in 45%. The prevalence of a tibial deformity did not differ between varus severity groups, whereas a femoral and bifocal deformity was significantly more prevalent in knees with more distinct varus (p < 0.001). Osteotomy simulation revealed that isolated high tibial osteotomy (HTO) was appropriate in only 12% for anatomic correction, whereas a double-level osteotomy was necessary in 63%. If overcorrection of mMPTA was tolerated, the number of HTOs significantly increased to 57% (p < 0.001), whereas the number of double-level osteotomies significantly decreased to 33% (p < 0.001). Isolated DFO was considered ideal in 8% for both simulations. Significantly more knees were considered "uncorrectable" by simulating anatomic correction (18 vs. 2%; p < 0.001). A double-level osteotomy was significantly more often necessary in knees with "severe" varus (p < 0.001).

Conclusion: Less than one-third of patients (28%) with mechanical varus ≥ 3° have a tibial deformity. If anatomic correction (mMPTA ≤ 90°) is intended, only 12% of patients can be corrected via isolated HTO, whereas 63% of patients require a double-level osteotomy. If slight overcorrection is accepted (mMPTA ≤ 95°), 57% of patients can be corrected via isolated HTO, whereas 33% of patients would still require a double-level osteotomy.

Level Of Evidence: III, cross-sectional study.
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http://dx.doi.org/10.1007/s00167-020-06166-3DOI Listing
July 2020

Failure Analysis in Patients With Patellar Redislocation After Primary Isolated Medial Patellofemoral Ligament Reconstruction.

Orthop J Sports Med 2020 Jun 22;8(6):2325967120926178. Epub 2020 Jun 22.

Department for Orthopaedic Sports Medicine, Technical University Munich, Munich, Germany.

Background: Reconstruction of the medial patellofemoral ligament (MPFL) has become a popular surgical procedure to address patellofemoral instability. As a consequence of the growing number of MPFL reconstructions performed, a higher rate of failures and revision procedures has been seen.

Purpose: To perform a failure analysis in patients with patellar redislocation after primary isolated MPFL reconstruction.

Study Design: Case series; Level of evidence, 4.

Methods: Patients undergoing revision surgery for reinstability after primary isolated MPFL reconstruction were included. Clinical notes were reviewed to collect demographic data, information on the primary surgery, and the mechanism of patellar redislocation (traumatic vs nontraumatic). Preoperative imaging was analyzed regarding femoral tunnel position and the prevalence of anatomic risk factors (ARFs) associated with patellofemoral instability: trochlear dysplasia (types B through D), patella alta (Caton-Deschamps index >1.2, patellotrochlear index <0.28), lateralization of the tibial tuberosity (tibial tuberosity-trochlear groove distance >20 mm, tibial tuberosity-posterior cruciate ligament [TT-PCL] distance >24 mm), valgus malalignment (mechanical valgus axis >5°), and torsional deformity (internal femoral torsion >25°, external tibial torsion >35°). The prevalence of ARF was compared between patients with traumatic and nontraumatic redislocations and between patients with anatomic and nonanatomic femoral tunnel position.

Results: A total of 26 patients (69% female) with a mean age of 25 ± 7 years were included. The cause of redislocation was traumatic in 31% and nontraumatic in 69%. Position of the femoral tunnel was considered nonanatomic in 50% of patients. Trochlear dysplasia was the most common ARF with a prevalence of 50%, followed by elevated TT-PCL distance (36%) and valgus malalignment (35%). The median number of ARFs per patient was 3 (range, 0-6), and 65% of patients had 2 or more ARFs. Patients with nontraumatic redislocations showed significantly more ARFs per patient, and the presence of 2 or more ARFs was significantly more common in this group. No significant difference was observed between patients with anatomic versus nonanatomic femoral tunnel position.

Conclusion: Multiple anatomic risk factors and femoral tunnel malposition are commonly observed in patients with reinstability after primary MPFL reconstruction. Before revision surgery, a focused clinical examination and adequate imaging including radiographs, magnetic resonance imaging (MRI), standing full-leg radiographs, and torsional measurement with computed tomography or MRI are recommended to assess all relevant anatomic parameters to understand an individual patient's risk profile. During revision surgery, care must be taken to ensure anatomic placement of the femoral tunnel through use of anatomic and/or radiographic landmarks.
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http://dx.doi.org/10.1177/2325967120926178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7309400PMC
June 2020

Visualization of Proximal and Distal Kaplan Fibers Using 3-Dimensional Magnetic Resonance Imaging and Anatomic Dissection.

Am J Sports Med 2020 07 14;48(8):1929-1936. Epub 2020 May 14.

Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Münster, Germany.

Background: In current magnetic resonance imaging (MRI) of the knee, injuries to the anterolateral ligament complex (ALC) and the Kaplan fibers (KFs) are not routinely assessed. As ruptures of the KFs contribute to anterolateral rotatory instability in the anterior cruciate ligament-deficient knee, detecting these injuries on MRI may help surgeons to individualize treatment.

Purpose: To visualize the KFs on 3-T MRI and to conduct a layer-by-layer dissection of the ALC.

Study Design: Descriptive laboratory study.

Methods: Ten fresh-frozen human cadaveric knees (mean ± SD age, 72 ± 8.5 years) without history of ligament injury were used in this study. Before layer-by-layer dissection of the ALC, MRI was performed to define the radiologic anatomy of the KFs. A coronal T1-weighted 3-dimensional turbo spin echo sequence and a transverse T2-weighted turbo spin echo sequence were obtained. Three-dimensional data sets were used for multiplanar reconstructions.

Results: KFs were identified in 100% of cases on MRI and in anatomic dissection. The mean length of the proximal and distal KFs was 17.9 ± 3.6 mm and 12.4 ± 6.5 mm, respectively. On MRI, the distance from the lateral femoral epicondyle to the proximal KFs was 35.9 ± 6.9 mm and to the distal KFs, 16.6 ± 4.1 mm; in anatomic dissection, the distances were 41.4 ± 8.1 mm for proximal KFs and 28.2 ± 8.1 mm for distal KFs. The distance from the lateral joint line to the proximal KFs was 63.5 ± 7.6 mm and to the distal KFs, 45.3 ± 3.7 mm. Interobserver reliability for image analysis was excellent for all measurements.

Conclusion: KFs can be consistently identified on MRI with use of 3-dimensional sequences. Subsequent anatomic dissection confirmed their close topography to the superior lateral genicular artery. For clinical implications, the integrity of the KFs should be routinely reviewed on MRI scans.

Clinical Relevance: As ruptures of the KFs contribute to anterolateral rotatory instability, accurate visualization of the KFs on MRI may facilitate surgical decision making for additional anterolateral procedures in the anterior cruciate ligament-deficient knee.
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http://dx.doi.org/10.1177/0363546520919986DOI Listing
July 2020

Promising clinical and magnetic resonance imaging results after internal bracing of acute posterior cruciate ligament lesions in multiple injured knees.

Knee Surg Sports Traumatol Arthrosc 2020 Aug 12;28(8):2543-2550. Epub 2020 Feb 12.

Department of Orthopaedic Sports Medicine, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany.

Purpose: The purpose of this study was to evaluate the clinical and radiological outcomes of acute posterior cruciate ligament (PCL) lesions in multiple injured knees that were surgically treated with internal bracing.

Methods: Acute complete PCL lesions in multiple injured knees with subsequent internal-bracing treatment within 21 days between 2014 and 2016 were eligible for inclusion. At final follow-up, patients were assessed with Tegner, Lysholm, and IKDC scores. PCL stability and healing were verified with KT-2000, stress radiography and magnetic resonance imaging (MRI).

Results: Fourteen patients [mean age 37.4 (± 17.8; SD) years] were evaluated after a mean follow-up of 19.9 (± 7.7; SD) months. Thirteen patients suffered complete lesions of the PCL with concomitant ligamentous injuries (Schenck I: six cases, Schenck III M: five cases, Schenck IV N: one case, Schenck V: one case). Median Tegner, mean Lysholm and mean IKDC scores at follow-up were 4 (2-7; interquartile range), 69.1 (± 16.6; SD) and 68.9 (± 18.1; SD) respectively. Posterior translation averaged 5.8 (± 2.2; SD) mm with the KT 2000 and stress radiography showed a mean posterior tibial translation of 5.5 (± 4.1; SD) mm in the side to side comparison. MRI showed adequate PCL healing.

Conclusions: Internal bracing as treatment for acute PCL ruptures in multiple injured knees showed adequate restoration of posterior tibial translation in a single-centre study including 14 cases.

Level Of Evidence: IV.
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http://dx.doi.org/10.1007/s00167-020-05852-6DOI Listing
August 2020

Excellent clinical outcome and low complication rate after proximal hamstring tendon repair at mid-term follow up.

Knee Surg Sports Traumatol Arthrosc 2020 Apr 24;28(4):1230-1235. Epub 2019 Oct 24.

Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.

Purpose: Proximal hamstring tendon avulsions lead to a significant loss of strength and a functional deficit of the respective lower limb and surgery is the recommended treatment. Only little is known about the clinical outcomes and complications when comparing acute and chronic management as well as partial and complete tears. Therefore, the purpose of this study was to investigate the clinical results and the complication rate of patients after surgical treatment of proximal hamstring tendon injuries. It was hypothesized that surgical treatment of an acute proximal hamstring avulsion would lead to a superior clinical outcome with a low complication rate and high return to sports rate compared to chronic cases and partial avulsions.

Methods: Patients who underwent proximal hamstring tendon repair between 2008 and 2015 were retrospectively evaluated with a minimum follow up of 2 years. Outcome measurements were obtained by means of Lysholm score, Harris Hip Score, Visual Analog Scale, and Tegner Activity Scale. Return to sports (RTS) rate was determined. Postoperative adverse events were recorded and complications reported. Patients' outcomes were compared between acute/chronic repair and partial/complete injury patterns.

Results: Ninety-four of 120 (78.3%) were available for final assessment at a mean follow-up of 56.2 ± 27.2 months. Clinical outcome measures were excellent and did not differ between the treatment groups or between the different injury patterns. RTS was achieved by 86.2% of the patients and was significantly superior after acute treatment (p < 0.05). The overall complication rate was 8.5% and significantly higher in complete tears compared to partial tears and in delay compared to acute surgery (p < 0.05).

Conclusion: Surgical treatment of proximal hamstring tendon avulsions results in excellent clinical outcome scores and a high RTS rate. Open surgical treatment has shown to be a safe procedure with a low complication rate. Surgical timing is important, as early surgical intervention provides a higher RTS rate and a lower complication rate than delayed surgery and should therefore be preferred in clinical practice. Repair of partial and complete tears lead to similar clinical outcome, but a higher complication rate in complete avulsions.

Level Of Evidence: Level IV.
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http://dx.doi.org/10.1007/s00167-019-05748-0DOI Listing
April 2020

Modified suture-bridge technique for tibial avulsion fractures of the posterior cruciate ligament: a biomechanical comparison.

Arch Orthop Trauma Surg 2020 Jan 26;140(1):59-65. Epub 2019 Sep 26.

Department of Orthopaedic Sports Medicine, Klinikum Rechts Der Isar, Technical University Munich, Ismaningerstr. 22, 81675, Munich, Germany.

Purpose: Displaced tibial posterior cruciate ligament (PCL) avulsion fractures require surgical fixation in order to provide an adequate bone healing and to avoid a loss of posterior stability. The purpose of this study was to compare the biomechanical properties of a recently established modified suture bridge technique to a well-established transtibial pullout technique. It was hypothesized that the suture bridge technique shows lower elongation and higher load to failure force compared to a transtibial pullout fixation.

Methods: Twelve fresh-frozen human cadaveric knees were biomechanically tested using an uniaxial hydrodynamic material testing system. A standardized bony avulsion fracture of the tibial PCL insertion was generated. Two different techniques were used for fixation: (A) suture bridge configuration and (B) transtibial pullout fixation. In 90° of flexion elongation, initial stiffness and failure load were determined.

Results: The suture-bridge technique resulted in a significant lower elongation (4.5 ± 2.1 mm) than transtibial pullout technique (12.4 ± 3.0 mm, p < 0.001). The initial stiffness at the beginning of cyclic loading was 46.9 ± 3.9 N/mm in group A und 40.8 ± 9.0 N/mm in group B (p = 0.194). Load to failure testing exhibited 286.8 ± 88.3 N in group A and 234.3 ± 96.8 N in group B (p = 0.377).

Conclusion: The suture bridge technique provides a significant lower construct elongation during cyclic loading. But postoperative rehabilitation must respect the low construct strength of both techniques because both fixation techniques did not show a sufficient fixation strength to allow for a more aggressive rehabilitation.
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http://dx.doi.org/10.1007/s00402-019-03278-5DOI Listing
January 2020

[All-arthroscopic fixation of tibial posterior cruciate ligament avulsion fractures with a suture-button technique].

Oper Orthop Traumatol 2020 Jun 6;32(3):236-247. Epub 2019 Sep 6.

Abteilung für Sportorthopädie, Klinikum rechts der Isar, TU München, Ismaninger Str. 22, 81675, München, Deutschland.

Objective: To restore the posterior stability of the knee after a tibial posterior cruciate ligament (PCL) avulsion with a suture-button construct.

Indications: Acute solid and monofragment bony avulsion of the tibial PCL insertion.

Contraindications: Chronic condition of avulsion fractures or posterior instability, multifragment avulsions, thin bone pieces, advanced knee osteoarthritis, high-grade soft tissue injury, infection.

Surgical Technique: Supine position, all-arthroscopic treatment via posteromedial and posterolateral portal, arthroscopic visualization and fracture reduction, transtibial drilling with a cannulated 2.4 mm drill, reduction of the fragment via FiberTape™ and Dog Bone. Knotting of the tapes against an additional Dog Bone at the anterior aspect of the tibia. Intraoperative x‑ray.

Postoperative Management: Knee extension brace with posterior tibial support for 6 weeks, 20 kg partial weight-bearing and restricted flexion up to 90° for 6 weeks, physiotherapy in prone position from the first postoperative day. Full weight bearing after x‑ray and clinical control after 6 weeks.

Results: Since 2016 eight tibial PCL avulsions were treated. In 6 patients a suture-bridge technique via a mini-open approach was performed due to a small or comminuted fracture fragment. In 2 patients an all-arthroscopic technique was performed. No complications. The all-arthroscopic technique requires a solid fragment and enables the surgeon to treat additional pathologies. In general, the arthroscopic technique makes the open posterior approach unnecessary. The arthroscopic techniques achieve slightly higher objective and subjective values compared to the open procedure, despite a higher rate of arthrofibrosis.
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http://dx.doi.org/10.1007/s00064-019-00626-xDOI Listing
June 2020

Varus alignment aggravates tibiofemoral contact pressure rise after sequential medial meniscus resection.

Knee Surg Sports Traumatol Arthrosc 2020 Apr 3;28(4):1055-1063. Epub 2019 Aug 3.

Department of Orthopedics and Sports Orthopedics, Technical University of Munich, Hospital Rechts der Isar, Munich, Germany.

Purpose: Arthroscopic partial meniscectomy of medial meniscus tears and varus alignment are considered independent risk factors for increased medial compartment load, thus contributing to the development of medial osteoarthritis. The purpose of this biomechanical study was to investigate the effect of lower limb alignment on contact pressure and contact area in the knee joint following sequential medial meniscus resection. It was hypothesized that a meniscal resection of 50% would lead to a significant overload of the medial compartment in varus alignment.

Methods: Eight fresh-frozen human cadaveric knees were axially loaded with a 750 N compressive force in full extension with the mechanical axis rotated to intersect the tibia plateau at 30%, 40%, 50%, 60% and 70% of its width. Tibiofemoral mean contact pressure (MCP), peak contact pressure (PCP), and contact area (CA) of the medial and lateral compartment were measured separately using pressure-sensitive films (K-Scan 4000, Tekscan) in four different meniscal conditions, respectively, intact, 50% resection, 75% resection, and total meniscectomy.

Results: Medial MCP was significantly increased when comparing the intact meniscus to each meniscal resection in all tested alignments (p < 0.05). Following meniscal resection of 50%, MCP was significantly higher with greater varus alignment compared to valgus alignment (p < 0.05). Similarly, medial PCP was higher at varus alignment compared to valgus alignment (p < 0.05). Further resection to 75% and 100% of the meniscus resulted in a significantly higher medial PCP at 30% of tibia plateau width compared to all other alignments (p < 0.05). Medial CA of the intact meniscus decreased significantly after 50%, 75% and 100% meniscal resection in all alignments (p < 0.05). Lateral joint pressure was not significantly increased by greater valgus alignment.

Conclusion: Lower limb alignment and the extent of medial meniscal resection significantly affect tibiofemoral contact pressure. Combined varus alignment and medial meniscal resection increased MCP and PCP within the medial compartment, whereas valgus alignment prevented medial overload. As a clinical consequence, lower limb alignment should be considered in the treatment of patients undergoing arthroscopic partial meniscectomy with concomitant varus alignment. In patients presenting with ongoing medial joint tenderness and effusion, realignment osteotomy can be a surgical technique to unload the medial compartment.
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http://dx.doi.org/10.1007/s00167-019-05654-5DOI Listing
April 2020

Effect of Lower Limb Alignment in Medial Meniscus-Deficient Knees on Tibiofemoral Contact Pressure.

Orthop J Sports Med 2019 Feb 6;7(2):2325967118824611. Epub 2019 Feb 6.

Department of Orthopedics and Sports Orthopedics, Rechts der Isar Hospital, Technical University of Munich, Munich, Germany.

Background: Degenerative medial meniscal tears and subsequent partial meniscal resection compromise meniscal function and lead to an overload of the medial compartment. In addition, lower limb alignment plays a key role in load distribution between the medial and lateral knee compartments, and varus alignment is a potential risk factor for medial osteoarthritis.

Purpose/hypothesis: The purpose of this biomechanical study was to investigate the effect of valgus and varus alignment on peak pressure and contact area in knees with concomitant horizontal medial meniscal tears and subsequent leaflet resection. It was hypothesized that varus alignment in combination with meniscal loss leads to the highest peak pressure within the medial compartment.

Study Design: Controlled laboratory study.

Methods: Six fresh-frozen human cadaveric knees were axially loaded using a 1000-N compressive load in full extension with the mechanical axis rotated to intersect the tibial plateau at 40%, 45%, 50%, 55%, and 60% of its width (TPW) to simulate varus and valgus alignment. Tibiofemoral peak contact pressure and contact area of the medial and lateral compartments were determined using pressure-sensitive foils in each of 4 different meniscal conditions: intact, 15-mm horizontal tear of the posterior horn, inferior leaflet resection, and resection of both leaflets.

Results: The effect of alignment on peak pressure (normalized to the neutral axis) within the medial compartment in cases of an intact meniscus was measured as follows: varus shift resulted in a mean increase in peak pressure of 18.5% at 45% of the TPW and 37.4% at 40% of the TPW, whereas valgus shift led to a mean decrease in peak pressure of 8.7% at 55% of the TPW and 23.1% at 60% of the TPW. Peak pressure changes between the intact meniscus and resection within the medial compartment was less in valgus-aligned knees (0.21 MPa at 60% TPW, 0.59 MPa at 50% TPW, and 0.76 MPa at 40% TPW). Contact area was significantly reduced after partial meniscal resection in the neutral axis (intact, 553.5 ± 87.6 mm; resection of both leaflets, 323.3 ± 84.2 mm; < .001). This finding was consistent in any alignment.

Conclusion: Both partial medial meniscal resection and varus alignment led to an increase in medial compartment peak pressure. Valgus alignment prevented medial overloading by decreasing contact pressure even after partial meniscal resection. A horizontal meniscal tear did not influence peak pressure and contact area even in varus alignment.

Clinical Relevance: As a clinical consequence, partial meniscal resection should be avoided to maintain the original biomechanical behavior, and the mechanical axis should be taken into account if partial meniscectomy is necessary.
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http://dx.doi.org/10.1177/2325967118824611DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6378645PMC
February 2019

[Rehabilitation after reconstruction of the posterior cruciate ligament].

MMW Fortschr Med 2018 12;160(21-22):69-71

Abteilung für Sportorthopädie, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, D-81675, München, Deutschland.

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http://dx.doi.org/10.1007/s15006-018-1240-3DOI Listing
December 2018

High short-term return to sports rate despite an ongoing healing process after acute meniscus repair in young athletes.

Knee Surg Sports Traumatol Arthrosc 2019 Jan 11;27(1):215-222. Epub 2018 Dec 11.

Department of Orthopaedic Sports Medicine, Klinikum Rechts der Isar, Technical University Munich, Ismaningerstr. 22, 81675, Munich, Germany.

Purpose: Acute meniscus repair in young athletes is always a challenge due to the long rehabilitation process and time to return to sport (RTS). The purpose was to investigate signal alterations in short-term follow-up after acute meniscus repair on specific magnetic resonance imaging (MRI) scan sequences. It was hypothesized that (1) MRI signal changes over the first postoperative healing phase and represent a continuous healing process and (2) meniscus healing properties correlates with clinical outcomes and RTS.

Methods: Young athletes with traumatic meniscus lesion and arthroscopic meniscus repair within 6 weeks and available preoperative MRI were enrolled. Clinical examination, outcome scores (IKDC, KOOS, Lysholm Score, Tegner activity score) and RTS were surveyed preoperatively and 6 and 12 weeks and 6 months after surgery. Radiological follow-up examinations were performed 2, 4, 6, 12 weeks and 6 months after operation using a 3T-MRI. Evaluation was based on ISAKOS meniscus classification system, meniscus healing were classified according to Henning's criteria.

Results: At final follow-up (FU) 30 patients (28 month, 2 week) with a total of 35 meniscus tears (19 medial, 16 lateral) were included. Clinical scores improved significantly after surgery: IKDC Score (preOP: 39.4 ± 18.5, final FU: 78.8 ± 15.3) KOOS (preOP: 45.7 ± 22.1, final FU: 82.7 ± 12.5) and Lysholm Score (preOP: 42.8 ± 23.7, final FU: 84.4 ± 13.8) (p < 0.01). Tegner activity score showed a steadily increase to 4 (range 3-9) at 6 months but did not reached the pre-injury level of 6 (range 3-9). RTS rate was 100% whereof 44.8% reached their pre-injury level. MRI examination revealed a continuous healing process and menisci were classified as 55.9% healed, 35.3% partially healed and 8.8% non-healed at final FU.

Conclusion: This study showed that MRI signal alterations of the meniscus steadily occur within the first 6 months postoperatively. MRI reveals an ongoing healing process at final FU that have to be carefully considered when RTS is discussed with high demanding patients. However, young athletes provide good clinical results and RTS rate even though MRI alterations are still present.

Level Of Evidence: Therapeutic study, prospective case series, Level IV.
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http://dx.doi.org/10.1007/s00167-018-5335-2DOI Listing
January 2019

Steep lateral tibial slope and lateral-to-medial slope asymmetry are risk factors for concomitant posterolateral meniscus root tears in anterior cruciate ligament injuries.

Knee Surg Sports Traumatol Arthrosc 2019 Aug 2;27(8):2585-2591. Epub 2018 Nov 2.

Department for Orthopedic Sports Medicine, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.

Purpose: To compare sagittal and coronal tibial slopes between anterior cruciate ligament (ACL) injured subjects with and without posterolateral meniscus root tear (PLRT).

Methods: A chart review was conducted to identify patients with isolated ACL tears and patients with an associated PLRT. Patients with other concomitant injuries and patients who underwent surgery > 6 months after the injury were excluded. Magnetic resonance image data were used to compare the medial and lateral sagittal tibial slope (MTS and LTS), lateral-to-medial slope asymmetry (LTS-MTS), and coronal slope of the tibial plateau between both groups. Mean LTS and standard deviation (SD) of the control group were calculated, and a value of > mean + 1 SD was considered an abnormal LTS. Interobserver reproducibility was assessed by calculating interclass correlation coefficients (ICCs) of measurements independently obtained by two reviewers.

Results: Fifty-nine patients met the in- and exclusion criteria. Thirty nine (66%) had an isolated ACL tear and 20 (34%) had an associated PLRT. Interrater ICCs for LTS, MTS, and coronal slope were 0.930, 0.884 and 0.825, respectively, representing good to excellent interobserver reproducibility. Patients with a PLRT had significantly steeper LTS (8.0 ± 3.2 vs. 4.0 ± 2.0; p < 0.001) and significantly greater difference of LTS-MTS (3.7 ± 2.9 vs. - 0.6 ± 2.0; p < 0.001). Furthermore, patients with abnormal LTS were significantly overrepresented among patients with PLRT (70% vs. 18%; p < 0.001). No significant difference between both groups was found for MTS and coronal slope.

Conclusion: A steep lateral tibial slope and lateral-to-medial slope asymmetry are risk factors for concomitant PLRT in ACL-injured subjects.

Level Of Evidence: IV, retrospective cohort study.
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http://dx.doi.org/10.1007/s00167-018-5279-6DOI Listing
August 2019

Repair of the lateral posterior meniscal root improves stability in an ACL-deficient knee.

Knee Surg Sports Traumatol Arthrosc 2018 Aug 27;26(8):2302-2309. Epub 2018 Apr 27.

Department of Orthopaedics and Sportsorthopaedics, Technical, University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.

Purpose: To investigate the stabilizing effect of a lateral meniscus posterior root repair in an ACL and root deficient knee.

Methods: The hypothesis of the current study was that a sequential transection of the posterior root and the meniscofemoral ligaments in an ACL-deficient knee increases rotational instability, and conversely, a repair of the meniscus root reduces the internal tibial rotation. Therefore, eight human knee joints were tested in a robotic setup (5 N m internal torque, 50 N m anterior translation load). Five conditions were tested: intact, ACL cut, ACL cut + lateral meniscus posterior root tear (LMRT), ACL cut + LMRT + transection of the MFL and ACL cut + lateral meniscus root repair. The angles of internal tibial rotation as well as anterior tibial translation were recorded.

Results: Transection of the lateral meniscus posterior root increased the internal tibial instability as compared to the ACL-insufficient state. A significant increase was detected in 60° and 90° of flextion. Sectioning of the meniscofemoral ligament further destabilized the knees significantly at all flexion angles as compared to the ACL-deficient state. Even in 30°, 60° and 90° a significant difference was detected as compared to the isolated root tear. A tibial fixation of the lateral meniscus root reduced the internal tibial rotation in all flexion angles and led to a significant decrease of internal tibial rotation in 30° and 90° as compared to the transection of the root and the MFL. The anterior tibial translation was increased in all conditions as compared to the native state.

Conclusion: A lateral meniscus root repair can reduce internal tibial rotation in the ACL-deficient knee. To check the condition of the lateral posterior meniscus root attachment is clinical relevant as a lateral meniscus root repair might improve rotational stability.
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http://dx.doi.org/10.1007/s00167-018-4949-8DOI Listing
August 2018

Postural control in elite decathlon athletes: are various modes of dynamic assessment needed?

J Sports Med Phys Fitness 2017 Jul-Aug;57(7-8):936-941

Department for Orthopedic Sports Medicine, Technical University of Munich, Munich, Germany.

Background: Decathlon consists of various track and field running, jumping and throwing events. This results in high physical demands and poor postural control may predispose athletes at a higher risk for injury. The purpose of this study was to measure and to show a relationship of different dynamic postural control tests in healthy professional decathlon athletes.

Methods: The German top decathlon team (eight professional athletes, mean age±standard deviation (SD), 20.8±2.7 years; mean height±SD, 187.1±4.3 cm; mean weight±SD, 82.1±7.2 kg) was tested. Star Excursion Balance Test (SEBT) and three different single-leg-hop tests (SLHT) (single hop for distance [SLH], crossover hop for distance [COH], triple hop for distance [TH] were measured and correlated.

Results: A significant correlation was evident between SLH and COH (r=0.861, P=0.003) and SLH and TH (r=0.908, P=0.001). The correlational analyses of SEBT revealed a significant relationship between the posteromedial and posterolateral direction of the SEBT (r=0.943, P<0.001). SEBT and SLHT showed no correlation.

Conclusions: The results of this study demonstrated a relationship in performance of different single leg hop tests in professional decathletes. Adversely there is no correlation of the single leg hop tests and the performance in the star excursion balance test. To minimize the time effort of testing procedures, to avoid redundant testing and to determine overall postural control in decathletes, test-batteries should include the SEBT and at least one SLHT.
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http://dx.doi.org/10.23736/S0022-4707.16.06416-1DOI Listing
December 2017

Biomechanical and viscoelastic properties of different posterior meniscal root fixation techniques.

Knee Surg Sports Traumatol Arthrosc 2017 Feb 11;25(2):403-410. Epub 2016 Jul 11.

Department of Orthopaedic Sports Medicine, Technische Universität München (TUM), Ismaninger Str. 22, 81675, Munich, Germany.

Purpose: The purpose of the present study was to biomechanically compare three different posterior meniscal root repair techniques. Transtibial fixation of a posterior meniscus root tear (PMRT) combined with an anterior cruciate ligament (ACL) reconstruction via one tunnel only shows similar properties in terms of cyclic loading and load to failure compared with direct anchor fixation.

Methods: Twenty-eight porcine knees were randomly assigned to 4 groups (n = 7 each): (1) native posterior meniscal root, (2) suture anchor repair, (3) refixation via a tibial ACL tunnel in combination with an interference screw fixation of the ACL graft, and (4) refixation via a tibial ACL tunnel in combination with an interference screw fixation of the ACL graft with an additional extracortical button fixation. The four groups underwent cyclic loading followed by a load-to-failure testing. Construct elongation during 1000 cycles, dynamic stiffness, attenuation, maximum force during load-to-failure testing, and failure mode were recorded.

Results: All reconstructions showed a significant lower maximum load (p < 0.0001) compared with the native meniscal root. The elongation for the transtibial fixation via the ACL tunnel without an additional extracortical backup fixation was significantly higher compared with the suture anchor technique (p < 0.0001). The additional use of a backup fixation led to similar results compared with the anchor repair technique.

Conclusion: The transtibial refixation of the meniscal root can be combined with an ACL reconstruction using the same tibial bone tunnel. However, an additional extracortical backup fixation is necessary. This might avoid a slippage of suture material and a failure of meniscus root fixation.
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http://dx.doi.org/10.1007/s00167-016-4237-4DOI Listing
February 2017

Acute Proximal Anterior Cruciate Ligament Tears: Outcomes After Arthroscopic Suture Anchor Repair Versus Anatomic Single-Bundle Reconstruction.

Arthroscopy 2016 12 17;32(12):2562-2569. Epub 2016 Jun 17.

Department of Orthopaedic and Trauma Surgery, Martin-Luther-Hospital, Berlin, Germany.

Purpose: To compare clinical and radiologic results of primary anterior cruciate ligament (ACL) suture anchor repair and microfracturing with anatomic ACL single-bundle reconstruction in patients with acute proximal ACL avulsion tears.

Methods: Between January 2010 and December 2013, 420 patients underwent ACL treatment. Forty-one patients were included in this study. The inclusion criteria were as follows: unilateral acute proximal ACL rupture, concomitant meniscus lesions, no previous knee ligament surgery, and no additional ligament injuries or absence of ligament injury of the contralateral knee. Preoperative magnetic resonance imaging confirming a proximal avulsion tear of the ACL was required. Patients had to undergo surgical treatment within 6 weeks after injury. Follow-up examination included Lachman and pivot-shift testing, KT-1000 measurement, and the International Knee Documentation Committee score.

Results: At a mean follow-up of 28 months (range, 24 to 31 month), 20 patients in each group were available. A mean KT-1000 arthrometer result of less than 3 mm indicated stability in all patients (P = .269). Three patients had a 1+ Lachman test (P = .072) and 4 patients had a 1+ pivot-shift test in the ACL repair group (P = .342). The International Knee Documentation Committee score results did not differ significantly (P > .99), but there was a significant correlation between poor results and failure rate (P = .001) in the refixation group. The failure rate was 15% in the ACL refixation group and 0% in the reconstruction group (P = .231). Magnetic resonance imaging confirmed homogeneous signal and proper ACL position in 100% of patients in the control group and 86% in the ACL repair group.

Conclusions: Proximal refixation of the ACL using knotless suture anchors and microfracturing restores knee stability and results in comparable functional outcomes to a control group treated with single-bundle ACL reconstruction. The results suggest that refixation of the ACL is a feasible treatment option in selected patients.

Level Of Evidence: Level III, case-control study.
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http://dx.doi.org/10.1016/j.arthro.2016.04.031DOI Listing
December 2016

[Subsequent damage following soccer injuries].

MMW Fortschr Med 2015 Jun;157(12):52-5

Abteilung für Sportorthopädie, Klinikum rechts der Isar, Ismaninger Str. 22, D-81675, München, Deutschland,

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http://dx.doi.org/10.1007/s15006-015-3282-0DOI Listing
June 2015

Different patterns of lateral meniscus root tears in ACL injuries: application of a differentiated classification system.

Knee Surg Sports Traumatol Arthrosc 2015 Jan 12;23(1):112-8. Epub 2014 Dec 12.

Abteilung für Sportorthopädie, Klinikum rechts der Isar, TU München, Ismaninger Str. 22, Munich, Germany.

Purpose: Posterior lateral meniscus root tears (PLMRTs) affect the intra-articular pressure distribution in the lateral compartment of the knee. The biomechanical consequences of these injuries are significantly influenced by the integrity of the meniscofemoral ligaments (MFLs). A newly introduced arthroscopic classification system for PLMRTs that takes MFL integrity into account has not yet been clinically applied but may be useful in selecting the optimal method of PLMRT repair.

Methods: Prospective ACL reconstruction data were collected. Concomitant injuries of the lateral meniscus posterior horn were classified according to their shape and MFL status. The classifications were: type 1, avulsion of the root; type 2, radial tear of the lateral meniscus posterior horn close to the root with an intact MFL; and type 3, complete detachment of the posterior meniscus horn.

Results: Between January 2011 and May 2012, 228 consecutive ACL reconstructions were included. Lateral and medial meniscus tears were identified in 38.2% (n = 87) and 44.7% (n = 102), respectively. Of the 87 lateral meniscus tears, 32 cases had PLMRTs; the overall prevalence of PLMRTs was 14% (n = 32). Two medial meniscus root tears were detected. All PLMRTs were classified according to the classification system described above, and the fixation procedure was adapted to the type of meniscus tear.

Conclusion: The PLMRT tear is a common injury among patients undergoing ACL repair and can be arthroscopically classified into three different types. Medial meniscus root tears are rare in association with ACL tears. The PLMRT classification presented here may help to estimate the injury's impact on the lateral compartment and to identify the optimal treatment. These tears should not be overlooked, and the treatment strategy should be chosen with respect to the type of root tear.

Level Of Evidence: IV.
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http://dx.doi.org/10.1007/s00167-014-3467-6DOI Listing
January 2015

Degradation of poly-D-L-lactide (PDLLA) interference screws (Megafix ®).

Arch Orthop Trauma Surg 2014 Aug 5;134(8):1147-53. Epub 2014 Jun 5.

Klinik für Orthopädie und Unfallchirurgie, Martin Luther Krankenhaus, Caspar Theyß Strasse 27-31, Grunewald, 14193, Berlin, Germany,

Introduction: Interference screw fixation is a standard procedure in anterior cruciate ligament (ACL) replacement. Aim of this study was to evaluate the degradation process of Poly-D-L-lactide (PDLLA) interference screws used for tibial ACL graft fixation.

Materials And Methods: We evaluated magnetic resonance imaging (MRI) scans of 18 patients who underwent ACL revision surgery at different time points after anatomic ACL reconstruction. At primary surgery, a tibial hybrid fixation was performed with a degradable interference (IF) screw made of PDLLA (Megafix(®)) and a button.

Results: MRI revealed three different phases of degradation of the PDLLA screw. 6-8 months after surgery the IF screw was clearly visible as a well-defined structure on MRI and CT scan. After 12-16 months, the screws appeared less defined with central ingrowths' of connective tissue. In some cases only fragmented screw material was visible. At these time points, there was a slight edema surrounding the tunnel visible on MRI. After 22 months and later, the mean screw site densities were comparable with the surrounding bone density. There was no edema or signs of inflammation around the bone tunnels visible. Presence of cystic or osteolytic changes was not detected.

Conclusion: After 22 months, a PDLLA screw may not interfere with ACL revision surgery. Regarding the degradation process of PDLLA screws, we noted three different phases. Furthermore, the degradation process observed by MRI resembles to that described by animal studies. The PDLLA screws fully absorb and are partially replaced by bone. The degradation process in humans seems to be longer than that described in animals.
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http://dx.doi.org/10.1007/s00402-014-2013-9DOI Listing
August 2014

The biomechanical effect of a lateral meniscus posterior root tear with and without damage to the meniscofemoral ligament: efficacy of different repair techniques.

Arthroscopy 2014 Jul 26;30(7):833-40. Epub 2014 Apr 26.

Klinik für Orthopädie und Unfallchirurgie, Martin-Luther-Krankenhaus, Berlin, Germany.

Purpose: To evaluate the effect of the meniscofemoral ligament (MFL) in maintaining lateral-compartment contact pressures after injury to the posterior root of the lateral meniscus, and to measure the ability to restore intra-articular loads to normal by repairing the posterior root to the tibia after transection of the posterior root and the MFL.

Methods: Ten human cadaveric knee joints were axially loaded to 100 N. A digital pressure sensor measured the contact pressure in the lateral compartment. Five different conditions were tested: intact, after release of the posterior root of the lateral meniscus, after transection of the MFL along with release of the posterior root, refixation of the posterior root of the lateral meniscus to the tibia using an anatomic transosseous tunnel, and refixation of the root of the lateral meniscus using a tibial anterior cruciate ligament (ACL) tunnel.

Results: After transection of the posterior lateral meniscus root, the contact pressure did not increase significantly. The additional transection of the MFL led to a significant increase in the contact pressure. Anatomic fixation of the meniscus posterior horn reduced the femorotibial pressure to nearly pre-sectioning values. The reattachment of the meniscus posterior horn through a tibial ACL tunnel was equivalent to an anatomic fixation.

Conclusions: In the case of a root tear of the lateral meniscus, the MFL maintains meniscus function and stabilizes the pressure in the lateral compartment. A complete detachment of the posterior meniscus horn (MFL and root tear) leads to an increase in the intra-articular pressure. A root repair normalizes the pressure down to normal values. The tibial ACL tunnel is suitable to perform the repair and to lead out the suture.

Clinical Relevance: In the case of a complete detachment of the meniscus posterior horn, fixation of the posterior root is necessary to restore the meniscus function and to guarantee an equal pressure distribution in the lateral compartment. It can be combined with an ACL reconstruction.
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http://dx.doi.org/10.1016/j.arthro.2014.02.040DOI Listing
July 2014

Midterm results following medial closed wedge distal femoral osteotomy stabilized with a locking internal fixation device.

Knee Surg Sports Traumatol Arthrosc 2015 Jul 28;23(7):2061-7. Epub 2014 Mar 28.

Klinik für Orthopädie und Unfallchirurgie, Martin Luther Krankenhaus, Berlin, Grunewald, Caspar Theyss Strasse 27-31, 14193, Berlin, Germany.

Purpose: Aim of this study was to evaluate the subjective and radiological outcome and to evaluate the complications of a medial closing wedge osteotomy at the femur for lateral osteoarthritis with genu valgum.

Methods: Twenty-three patients with grade III to IV cartilage damage and valgus knee alignment were treated with medial closing wedge osteotomy at the distal femur. The osteotomy was stabilized with an internal plate fixator. Age varied between 25 and 55 years (mean 47 years). One patient was lost to final follow-up.

Results: After 3.5 years, all Knee Osteoarthritis Outcome Score (KOOS) subitems increased significantly. There was no significant difference in the subgroup analysis of KOOS subitems for patients with and without microfracture or age (>50 vs. <50 years). There were no perioperative complications. One patient had an overcorrection. All, but one osteotomy, showed stable bone healing. There was a loss of correction due to delayed bone healing in one case. Possible explanations for this complication were injury of the lateral cortex or smoking. This case required revision with bone graft and an additional lateral plate. In no case, a conversion to an endoprosthesis was necessary.

Conclusion: The femoral medial closing wedge osteotomy is a surgical method for improving symptoms of lateral osteoarthritis in the valgus knee.

Level Of Evidence: IV.
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http://dx.doi.org/10.1007/s00167-014-2953-1DOI Listing
July 2015

Posterior root tear of the medial and lateral meniscus.

Arch Orthop Trauma Surg 2014 Feb 10;134(2):237-55. Epub 2013 Dec 10.

Klinik für Orthopädie und Unfallchirurgie, Martin Luther Krankenhaus, Berlin, Caspar Theyss Strasse 27-34, Grunewald, 14193, Berlin, Germany.

An avulsion of the tibial insertion of the meniscus or a radial tear close to the meniscal insertion is defined as a root tear. In clinical practice, the incidence of these lesions is often underestimated. However, several biomechanical studies have shown that the effect of a root tear is comparable to a total meniscectomy. Clinical studies documented progredient arthritic changes following root tears, thereby supporting basic science studies. The clinical diagnosis is limited by unspecific symptoms. In addition to the diagnostic arthroscopy, MRI is considered to be the gold standard of diagnosis of a meniscal root tear. Three different direct MRI signs for the diagnosis of a meniscus root tear have been described: Radial linear defect in the axial plane, vertical linear defect (truncation sign) in the coronal plane, and the so-called ghost meniscus sign in the sagittal plane. Meniscal extrusion is also considered to be an indirect sign of a root tear, but is less common in lateral root tears. During arthroscopy, the function of the meniscus root must be assessed by probing. However, visualization of the meniscal insertions is challenging. Refixation of the meniscal root can be performed using a transtibial pull-out suture, suture anchors, or side-to-side repair. Several short-term studies reported good clinical results after medial or lateral root repair. Nevertheless, MRI and second-look arthroscopy revealed high rates of incomplete or absent healing, especially for medial root tears. To date, most studies are case series with short-term follow-up and level IV evidence. Outerbridge grade 3 or 4 chondral lesions and varus malalignment of >5° were found to predict an inferior clinical outcome after medial meniscus root repair. Further research is needed to evaluate long-term results and to define evident criteria for meniscal root repair.
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http://dx.doi.org/10.1007/s00402-013-1873-8DOI Listing
February 2014

Technique of anatomical footprint reconstruction of the ACL with oval tunnels and medial portal aimers.

Arch Orthop Trauma Surg 2013 Jun 30;133(6):827-33. Epub 2013 Apr 30.

Department of Orthopaedic and Trauma Surgery, Martin Luther Hospital, Caspar Theyss Strasse 27-34, Grunewald, 14193, Berlin, Germany.

Purpose: The purpose of this article was to demonstrate an anterior cruciate ligament (ACL) reconstruction technique using oval tunnels. Aim of this single bundle technique is to fit the footprint anatomy of the ACL as closely as possible. TECHNIQUE AND PATIENTS: The presented technique is a single bundle technique using a semitendinosus graft. For femoral tunnel placement, a specific medial portal aimer (Karl Storz, Tuttlingen, Germany) is used. Aiming and drilling of the femoral tunnel are performed via the medial portal. Oval tunnels are created by stepwise dilatation with ovally shaped dilatators. The position of the femoral tunnel is visualized and controlled with the arthroscope via the medial portal. For the tibial tunnel placement, a specific aimer was used as well. With this technique, 24 patients were operated and all intra- and postoperative complications were analyzed prospectively. The tunnel position was documented postoperatively by CT scan.

Results: There were no significant intra- and postoperative complications associated with the oval tunnel technique. The postoperative 3D CT scan revealed that all femoral and tibial tunnels were located within the area of the anatomical ACL insertions.

Conclusions: This article presents an ACL reconstruction technique using oval dilatators and medial portal aimers to create oval tunnels. These oval tunnels match the insertion site anatomy much closer than round tunnels do.

Level Of Evidence: Level IV, case series.
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http://dx.doi.org/10.1007/s00402-013-1741-6DOI Listing
June 2013

Biomechanical consequences of a posterior root tear of the lateral meniscus: stabilizing effect of the meniscofemoral ligament.

Arch Orthop Trauma Surg 2013 May 31;133(5):621-6. Epub 2013 Mar 31.

Klinik für Orthopädie und Unfallchirurgie, Martin Luther Krankenhaus, Caspar Theyss Strasse 27-34, Grunewald, Berlin, Germany.

Purpose: The purpose of this study was to evaluate the effects of different types of lateral meniscus root tears in terms of tibiofemoral contact stress.

Methods: Ten porcine knees each underwent five different testing conditions with the menisci intact, a simulated lateral posterior root tear with and without cutting the meniscofemoral ligament and with an artificial tear of the posterior root of the medial meniscus. Biomechanical testing was performed at 30° of flexion with an axial load of 100 N. A pressure sensor (st Sensor Type S2042, Novel, Munich) was used to measure the tibiofemoral contact area and the tibiofemoral contact pressure. Data were analyzed to assess the differences in contact area and tibiofemoral peak contact pressure among the five meniscal conditions.

Results: There was no significant difference in mean contact pressure between the state with the menisci intact and an isolated posterior root tear of the lateral meniscus. In case of a root tear and a tear of the meniscofemoral ligament, the contact area decreased in comparison with the intact state of the menisci. After additional cutting of the meniscofemoral ligament, the tibiofemoral contact pressure was significantly higher in comparison with the intact state and the avulsion injury. In the medial compartment, joint compression forces were significantly increased in comparison with the intact state after cutting the posterior root of the medial meniscus (P < 0.05).

Conclusions: The consequence of a medial meniscus root tear is well known and was verified by this analysis. The results of the present study show that the biomechanical consequences of a lateral meniscus root tear depend on the state of the meniscofemoral ligament. An increase in tibiofemoral contact pressure is only to be expected in combined injuries of the meniscus root and the meniscofemoral ligaments.

Clinical Relevance: Posterior lateral meniscus root tear might have a better prognosis in terms of the development of osteoarthritis when the meniscofemoral ligament is intact.
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http://dx.doi.org/10.1007/s00402-013-1716-7DOI Listing
May 2013

Posterior root tear fixation of the lateral meniscus combined with arthroscopic ACL double-bundle reconstruction: technical note of a transosseous fixation using the tibial PL tunnel.

Arch Orthop Trauma Surg 2012 Mar 13;132(3):387-91. Epub 2011 Nov 13.

Clinic for Orthopaedic and Trauma Surgery, Martin Luther Hospital, Caspar-Theyss-Strasse 27-31, Berlin, Germany.

According to our observation in ACL reconstruction, we find root tears of the posterior horn of the lateral meniscus as a common concomitant injury in ACL-deficient knees. This might be a consequence of initial trauma or of the increased anterior-posterior translation of the tibia and an overload impact on the posterior meniscus root in ACL-deficient knees. A tear of the posterior horn of the medial meniscus causes a 25% increase in peak pressure in the medial compartment compared with that found in the intact condition. The repair restores the peak contact pressure to normal (Allaire et al. in J Bone Joint Surg Am 90(9):1922-1931, [2008]). A tear of the posterior horn of the lateral meniscus might have similar consequences. We hypothesize the surgical anatomical reattachment of the root at the tibia helping to restore knee joint kinematics and helping to advance ACL-graft function. This article presents an arthroscopical technique to reattach the posterior meniscus root in combination with ACL double-bundle reconstruction. The procedure uses the tibial PL tunnel to fix the meniscus suture.
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http://dx.doi.org/10.1007/s00402-011-1429-8DOI Listing
March 2012