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Medicine (Baltimore) 2019 Jun;98(24):e16011

Orthopaedic Medical Center, The Second Hospital of Jilin University, Changchun, China.

Rationale: Upper pole sleeve fractures of the patella are rare in adolescents; however, they are serious injuries that require early diagnosis and treatment.

Patient Concerns: We present a rare case of a 15-year-old girl who suffered a sleeve fracture at the superior pole of the right patella. The patient had a history of dislocation of the patella 2 weeks ago. Read More

J Orthop Case Rep 2018 May-Jun;8(3):18-22

Department of Orthopaedic Surgery, NYU Langone Medical Center, Hospital for Joint Diseases, New York, USA.

Introduction: Isolated tibial tubercle fractures or patellar tendon ruptures are common injuries in adolescents. However, combined tubercle fractures with patellar tendon ruptures are rare, and hence, there are no definitive methods of surgical fixation or post-operative protocols.

Case Report: A 13-year-old healthy girl sustained an extensor mechanism injury after the left knee hyperflexion during a fall from skateboarding. Read More

Am J Sports Med 2018 12 14;46(14):3400-3406. Epub 2018 Nov 14.

Division of Orthopaedics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.

Background: Abnormalities in the trochlea-patella-tibia relationship have been shown to be risk factors for recurrent patellofemoral instability, although no current measurements quantify patellar containment in the trochlea. Standard measurements, such as tibial tubercle-trochlear groove (TT-TG) distance, do not account for the containment of the patella by the trochlea. Our goal was to develop a measurement to assess how well the trochlea contained the extensor mechanism. Read More

Z Orthop Unfall 2018 Oct 5;156(5):593-607. Epub 2018 Oct 5.

Ruptures of the extensor mechanism of the knee joint are rare but disabling injuries. Injuries occur on the basis of degeneration or acute trauma. The understanding of anatomy and biomechanical function plays an essential role for choosing the right diagnostic methods and initiating successful treatment. Read More

Am J Orthop (Belle Mead NJ) 2018 Aug;47(8)

Tripler Army Medical Center, Honolulu, HI.

The purpose of this study is to determine the prevalence of potential graft-influencing pathologies of the extensor mechanism of the knee in patients presenting with a primary anterior cruciate ligament (ACL) rupture. We performed a retrospective review of the plain radiographs and magnetic resonance imaging (MRI) of all active-duty patients presenting with a primary ACL rupture at our institution between July 2006 and February 2009. Imaging was reviewed to determine the presence of a multipartite patella, unresolved Osgood-Schlatter's disease, and/or radiographic evidence suggestive of patella tendinopathy. Read More

Am J Orthop (Belle Mead NJ) 2018 Apr;47(4)

American Knee Institute, Hinsdale Orthopaedic Associates, Westmont, IL.

Blunt trauma to the anterior knee typically results in a contusion or fracture of the patella. Additionally, injury to the extensor mechanism may come from a partial or full disruption of the patellar or quadriceps tendon. A professional baseball player suffered an injury to his knee after he collided with an outfield wall. Read More

BMJ Case Rep 2018 Feb 7;2018. Epub 2018 Feb 7.

Pathology and Laboratory Medicine, King Fahad Specialist Hospital, Dammam, Saudi Arabia.

A young patient presented with a progressive right knee pain and swelling that was worse on ambulation. Following appropriate investigations, he was confirmed having Ewing's sarcoma of the right patella. Two cycles of chemotherapy were initiated before he sustained a fall and a resultant pathological patellar fracture. Read More

J Knee Surg 2018 Feb 4;31(2):141-154. Epub 2018 Jan 4.

Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts.

The tendons of the knee play a critical role in the motion and stability of the knee. Knee pain, a common clinical complaint, can frequently be attributed to pathology of these structures. While the cornerstones of the radiological evaluation of the knee are radiography and magnetic resonance imaging, ultrasound can also play an important diagnostic role and can be useful for guided interventional procedures. Read More

Sports Med Arthrosc Rev 2017 Dec;25(4):227-236

Departments of *Orthopaedic Surgery §Radiology, University of Minnesota †University of Minnesota Medical School, Minneapolis ‡Department of Radiology, Mayo Clinic, Rochester, MN.

The patellofemoral joint is an articulation between the patella and the femoral trochlea, which serves to increase the lever arm of the extensor mechanism. The stability of the patella within the trochlear groove is supported statically by the bony confines of the groove itself, as well as the medial patellofemoral ligament, and dynamically by the vastus musculature. Pathologic changes seen on magnetic resonance imaging (MRI) are frequently well correlated with findings found by arthroscopy at the time of surgery. Read More

Oper Orthop Traumatol 2017 Dec 25;29(6):509-519. Epub 2017 Oct 25.

Chirurgisch-Traumatologisches Zentrum, Asklepios Klinik St. Georg, Lohmühlenstraße 5, 20099, Hamburg, Deutschland.

Objective: Anatomic reconstruction of the retropatellar articular surface and repair of the extensor mechanism of the knee joint. The osteosynthesis should allow immediate mobilization as part of an early functional postoperative rehabilitation protocol.

Indications: Displaced fractures of the patella, especially multifragment and comminuted fractures with a retropatellar incongruity or dislocation of >2 mm. Read More

J Orthop Case Rep 2017 May-Jun;7(3):5-8

Department of Orthopaedics, St. John's Medical College Hospital, Bengaluru, Karnataka, India.

Introduction: Acute concomitant rupture of both anterior cruciate ligament (ACL) and patellar tendon is a rare injury. The diagnosis of either of the injuries may be missed on clinical examination in the emergency room. A high index of suspicion is necessary when active extension is absent, and necessary investigations like ultrasound or magnetic resonance imaging (MRI) should be done to confirm the diagnosis. Read More

Injury 2017 Nov 1;48(11):2515-2521. Epub 2017 Sep 1.

Department of Orthopaedic Surgery, Texas Children's Hospital, Houston, TX, USA.

Background: Intact knee extensor mechanism is required for the normal function of the lower extremity. Patellar tendon rupture is a relatively rare injury with peak age incidence around 40 years and usually occurs midsubstance. The occurrence of pure patellar tendon rupture without bony avulsion is an extremely rare injury in the pediatric population with few cases reported in the literature with limited information regarding frequency, complications, and outcomes in children. Read More

Eklem Hastalik Cerrahisi 2017 Aug;28(2):128-31

Department of Orthopedics and Traumatology, Medical Faculty of Gazi University, 06500 Beşevler, Ankara, Turkey.

Congenital dislocation of the patella is a disorder that presents with dysfunction in extensor mechanism. Although congenital dislocation of the patella mostly occurs in children with genetic disorders, it may also occur in totally healthy children, despite rarely. In this article, we report a 16-year-old male patient who referred to our clinic with complaints of gait disturbance, frequent falls, and muscular weakness in lower extremity. Read More

J Am Acad Orthop Surg 2017 May;25(5):365-374

From the Division of Sports Medicine, Department of Orthopaedics, University of Rochester School of Medicine and Dentistry, Rochester, NY.

The knee is one of the most commonly injured joints in the body. Its superficial anatomy enables diagnosis of the injury through a thorough history and physical examination. Examination techniques for the knee described decades ago are still useful, as are more recently developed tests. Read More

Knee 2017 Mar 1;24(2):468-476. Epub 2016 Dec 1.

NYU Hospital for Joint Diseases, 301 E17th Street, New York, NY 10003, United States.

Background: Patellar tendon rupture is rare in the general population. Typically, failure occurs proximally or at the mid-substance. Distal avulsion from the tibial tubercle in adults is rare and not well described in the orthopedic literature. Read More

J Orthop Res 2017 05 12;35(5):965-973. Epub 2016 Dec 12.

McClure Musculoskeletal Research Center, Department of Orthopedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont.

The complex inter-segmental forces that are developed across an extended knee by body weight and contraction of the quadriceps muscle group transmits an anteriorly directed force on the tibia that strain the anterior cruciate ligament (ACL). We hypothesized that a relationship exists between geometry of the knees extensor mechanism and the risk of sustaining a non-contact ACL injury. Geometry of the extensor mechanism was characterized using MRI scans of the knees of 88 subjects that suffered their first non-contact ACL injury and 88 matched control subjects with normal knees that were on the same team. Read More

BMC Musculoskelet Disord 2016 11 24;17(1):487. Epub 2016 Nov 24.

Norwich Radiology Academy, Norfolk and Norwich University Hospitals NHS Foundation Trust, Colney Lane, Norwich, Norfolk, NR4 7UB, UK.

Background: Fluid in the subcutaneous fat is a common finding anterior to the knee on MRI. This may be caused by chronic low-grade shearing injuries in patients who are overweight. The purpose of this study was to determine if there is a difference in the amount of subcutaneous fat around the knee between patients with these appearances and controls. Read More

J Am Acad Orthop Surg 2016 Dec;24(12):e184-e192

From the Knee Unit, Clínica Alemana, Universidad del Desarrollo, Santiago, Chile.

Patellar tendinopathy is a common cause of pain in athletes' knees. Historically, it has been related to jumping sports, such as volleyball and basketball. Repetitive jumping generates a considerable load of energy in the extensor mechanism, leading to symptoms. Read More

West J Emerg Med 2016 Nov 29;17(6):814-816. Epub 2016 Sep 29.

Stanford University School of Medicine, Department of Emergency Medicine, Stanford, California.

Traumatic injuries to the knee are common in emergency medicine. Bedside ultrasound (US) has benefits in the rapid initial detection of injuries to the patella. In addition, US can also quickly detect injuries to the entire knee extensor mechanism, including the quadriceps tendon and inferior patellar ligament, which may be difficult to diagnose with plain radiographs. Read More

Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 2015 Oct;29(10):1204-7

Objective: To explore the effectiveness of knee extensor mechanism reconstruction in the treatment of recurrent patellar subluxation with bone anchor in adolescents.

Methods: Between January 2010 and December 2013, 20 patients with patellar subluxation were treated by knee extensor mechanism reconstruction with bone anchor. There were 11 males and 9 females, aged from 12 to 17 years (mean, 15. Read More

Arthroscopy 2016 Jan;32(1):69-70

The MRI tibial tubercle-trochlear groove distance is statistically significantly higher in adolescent and young adults with noncontact anterior cruciate ligament (ACL) tears compared with those without tears. The authors use lateral thinking to assess this marker for extensor mechanism alignment as a potential risk factor for ACL tear. Yet the approximate 2 mm increase seen in those with ACL tears portends unproven clinical significance. Read More

Radiographics 2015 Sep-Oct;35(5):1483-501. Epub 2015 Aug 21.

From the Department of Radiology and Imaging, Hospital for Special Surgery, 535 E 70th St, New York, NY 10021.

Primary total knee arthroplasty is a highly effective treatment that relieves pain and improves joint function in a large percentage of patients. Despite an initially satisfactory surgical outcome, pain, dysfunction, and implant failure can occur over time. Identifying the etiology of complications is vital for appropriate management and proper timing of revision. Read More

Scand J Surg 2016 Jun 13;105(2):67-72. Epub 2015 Aug 13.

Töölö Hospital, Helsinki University Central Hospital, HUS, Helsinki, Finland.

Background And Aims: Quadriceps and patella tendon ruptures are uncommon injuries often resulting from minor trauma typically consisting of an eccentric contraction of the quadriceps muscle. Since rupture of a healthy tendon is very rare, such injuries usually represent the end stage of a long process of chronic tendon degeneration and overuse. This review aims to give an overview of the current understanding of the pathophysiology, diagnostic principles, and recommended treatment protocols as supported by the literature and institutional experience. Read More

Int Orthop 2015 Aug 20;39(8):1587-92. Epub 2015 Jun 20.

Department of Orthopaedics, Sancheti Institute, Pune, India.

Purpose: Treatment of congenital knee dislocation (CDK) depends on the severity and flexibility of the deformity. Various modalities of treatment ranging from serial cast, open quadricepsplasty and minimally invasive quadricepsplasty have been described. We describe percutaneous needle quadriceps tenotomy for treatment of flexible CDK and present our result of retrospective case series. Read More

Am J Sports Med 2015 Jun 17;43(6):1362-72. Epub 2015 Mar 17.

School of Surgery (Orthopaedics), University of Western Australia, Perth, Australia.

Background: While matrix-induced autologous chondrocyte implantation (MACI) has demonstrated encouraging outcomes in the treatment of knee chondral defects, there remains little available research specifically investigating its use in the patellofemoral joint.

Purpose: To prospectively evaluate the clinical and radiologic outcome of MACI in the patellofemoral joint.

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

Magn Reson Imaging Clin N Am 2014 Nov 1;22(4):601-20. Epub 2014 Nov 1.

Department of Radiology, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI 48109, USA.

Anterior knee pain is associated with many different causes. The clinical diagnosis may be unclear when the patient initially presents for evaluation. Magnetic resonance (MR) imaging is a valuable modality with high diagnostic accuracy in the evaluation of extensor mechanism pathology, which commonly presents with anterior knee pain. Read More

Pediatr Radiol 2014 Nov 21;44(11):1436-45; quiz 1433-6. Epub 2014 Oct 21.

Department of Radiology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., MLC 5031, Cincinnati, OH, 45229, USA,

Although avulsion fractures of the pediatric knee are uncommon, they are important injuries to recognize because they are frequently associated with adjacent soft-tissue and osteocartilaginous abnormalities. Related injuries, which include entrapment of soft-tissue structures, intra-articular fracture extension, and intra-articular loose bodies, can complicate or alter therapy. The most commonly affected soft-tissue structures include the cruciate ligaments, collateral ligaments and supporting tendons, and extensor mechanism and retinacula. Read More

Iowa Orthop J 2014 ;34:24-9

University of Iowa Department of Orthopaedics & Rehabilitation Division of Sports Medicine.

Background: A laterally tracking patella is commonly seen in patients with chronic recurrent lateral patellar dislocations. Clinical appearance of the J-sign occurs when the patella is congruent with the trochlear groove in flexion and moves over the lateral border of the femoral condyle as the lower leg reaches complete extension. A Fulkerson osteotomy procedure corrects this maltracking of the patella by medially transferring the tibial tubercle. Read More

Knee 2014 Oct 19;21(5):979-81. Epub 2014 Jul 19.

University Hospital of North Staffordshire, Newcastle Road, Stoke-on-Trent ST4 6QB, UK.

In anatomical studies the deepest soft tissue layer, related to the deep rectus femoris tendinous fibers, has been described as the "prepatellar quadriceps continuation". We present an unusual case of an isolated prepatellar continuation rupture, which to our knowledge is the first described case in the literature. Injuries to the extensor mechanism may include isolated rupture of the prepatellar continuation with intact quadriceps and patellar tendons. Read More

Med Clin North Am 2014 Jul 24;98(4):719-36, xi. Epub 2014 Apr 24.

Department of Orthopaedic Surgery, Penn State Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, 30 Hope Drive, Hershey, PA 17033, USA. Electronic address:

Acute knee pain is a common complaint among patients presenting to outpatient clinics. Although most injuries are minor and resolve without surgical intervention, some injuries, such as extensor mechanism injuries, tibial plateau fractures, and multi-ligament knee injuries, require prompt evaluation by an orthopedic surgeon. A thorough history and physical examination combined with radiographs are usually sufficient to diagnose these more urgent injuries. Read More

Knee Surg Sports Traumatol Arthrosc 2014 Oct 11;22(10):2522-30. Epub 2014 May 11.

School of Surgery, University of Western Australia, Perth, Australia,

Purpose: Both autologous chondrocyte implantation (ACI) and tibial tubercle transfer (TTT) have been used to treat chondral defects in the patellofemoral joint resulting in clinical improvement. Our study investigates the magnetic resonance imaging (MRI) appearance of the matrix-induced autologous chondrocyte implantation (MACI) graft at 5-year follow-up to determine if it provides a durable treatment option in patients with an average age of 42 (standard deviation 11.6). Read More

Eur J Orthop Surg Traumatol 2015 Jan 24;25(1):141-8. Epub 2014 Apr 24.

Department of Orthopedics and Traumatology, Antalya Education and Research Hospital, Kultur mah. 3805 Sk. Durukent Sit., F Blok Daire 22, Kepez, Antalya, Turkey.

Objective: The purpose of this prospective study was to examine the prevalence of occult knee injuries in patients with ipsilateral tibial shaft fractures and determine their impact on clinical outcome.

Materials And Methods: Preoperative knee MRI examination was performed in 41 patients (42 knees) with isolated tibial shaft fractures. Menisci, cruciate ligaments, collateral ligaments, extensor mechanism, osteochondral lesions, bone contusions and knee effusion were evaluated. Read More

Acta Orthop Traumatol Turc 2014 ;48(2):231-5

Department of Orthopedics and Traumatology, Dr. Lütfi Kırdar Kartal Training and Research Hospital, İstanbul, Turkey.

Anterior cruciate ligament injuries are common, mostly occurring during sports trauma. Conversely, patellar tendon ruptures are uncommon injuries secondary to forceful contractions of the extensor mechanism. It is important to consider the possibility of combined injuries around the knee. Read More

J Bone Joint Surg Am 2014 Feb;96(4):318-24

Departments of Orthopaedics and Rehabilitation (A.J.D., N.T.M., A.D., and G.T.) and Emergency Medicine (D.T.), University of New Mexico Health Sciences Center, 1 University of New Mexico, MSC10 5600, Albuquerque, NM 87131. E-mail address for A.J. Dickens:

Background: The tibial tubercle-trochlear groove (TT-TG) distance is a useful tool in guiding surgical management for patients with recurrent lateral patellar instability. Current recommendations for tibial tubercle transfer are based on TT-TG distance thresholds derived from adult populations. Recurrent patellar instability, however, frequently affects children, but normal and pathological TT-TG values have not been established for pediatric patients. Read More

J Med Liban 2013 Jul-Sep;61(3):183-6

Musculoskeletal Radiology Section-Dept of Radiology, University of Iowa Hospitals and Clinics, Iowa City, USA.

Tophaceous gout presenting as a soft tissue mass in an unusual location can pose a diagnostic challenge for radiologists. Tophi sometimes occur in a variety of unusual anatomic locations making them difficult to distinguish from tumors such as sarcomas. We report two cases of gout in the extensor mechanism of the knee, with imaging findings that were initially concerning for a neoplasm. Read More

Orthop Traumatol Surg Res 2014 Feb 10;100(1 Suppl):S125-37. Epub 2014 Jan 10.

Hôpital Universitaire Femme-Mère-Enfant de Lyon, Hospices civils de Lyon, Université Claude-Bernard Lyon I, Service d'Orthopédie Pédiatrique, 59, boulevard Pinel, 69677 Bron, France.

Paediatric patellar instability encompasses many anatomic entities located along a continuum of knee extensor mechanism abnormalities. Major or minor clinical manifestations may occur at a variable age. In major forms with irreducible patellar dislocation or habitual patellar dislocation during knee flexion, shortness of the quadriceps is a consistent feature. Read More

J Knee Surg 2013 Oct 16;26(5):301-8. Epub 2013 Aug 16.

Division of Orthopedic Trauma, Department of Orthopedics and Rehabilitation, Vanderbilt University Medical Center, Nashville, Tennessee.

The diagnosis of quadriceps and patellar tendon ruptures requires a high index of suspicion and thorough history-taking to assess for medical comorbidities that may predispose patients to tendon degeneration. Radiographic assessment with plain films supplemented by ultrasound and magnetic resonance imaging when the work-up is equivocal further aids diagnosis; however, advanced imaging is often unnecessary in patients with functional extensor mechanism deficits. Acute repair is preferred, and transpatellar bone tunnels serve as the primary form of fixation when the tendon rupture occurs at the patellar insertion, with or without augmentation depending on surgeon preference. Read More

Radiol Clin North Am 2013 May 17;51(3):393-411. Epub 2013 Jan 17.

Department of Radiology, Nuffield Orthopaedic Centre, Oxford University Hospitals, Oxford, UK.

Disorders related to the knee extensor mechanism are common and rarely require imaging. Non specific anterior knee pain, fracture, dislocation, overuse tendinopathy and chronic patellofemoral instability are the commonest conditions encountered. Imaging is used in acute trauma, and for the assessment of cases of anterior knee pain resistant to conservative measures. Read More

Acta Orthop Belg 2012 Dec;78(6):764-70

Royal Derby Hospital, Derby, UK.

Ruptures of the patellar and quadriceps tendon are rare injuries requiring immediate repair to re-establish knee extensor continuity and allow early motion. Ultrasound is extensively used as a diagnostic tool before surgery on acute traumatic tears of the patellar tendon and quadriceps tendons. The aim of our study was to evaluate the role of sonography in diagnosing quadriceps and patellar tendon rupture and in differentiating partial from complete tears. Read More

J Knee Surg 2013 Dec 21;26 Suppl 1:S123-7. Epub 2012 Sep 21.

Shelbourne Knee Center, Indianapolis, Indiana.

This is a case report of a young athlete who sustained a partial tear of the patellar tendon after anterior cruciate ligament (ACL) reconstruction with a bone-patellar tendon-bone (BPTB) autograft. The injury, diagnostic workup, and decision-making process that lead to the choice of nonsurgical treatment are described. Furthermore, the rehabilitation process is described in detail. Read More

BMJ Case Rep 2012 Nov 27;2012. Epub 2012 Nov 27.

Department of Orthopaedics, Royal Berkshire NHS Foundation Trust, Reading, UK.

Calcific tendonitis of the quadriceps tendon is an uncommon condition. We present the first case of a quadriceps tendon tear associated with calcific tendonitis. In this case, the patient presented with symptoms mimicking a rupture of the quadriceps tendon. Read More

Clin Orthop Relat Res 2012 Aug 9;470(8):2253-60. Epub 2012 Feb 9.

Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA, USA.

Background: A lateralized tibial tubercle is one potential cause of patellar instability. The tibial tubercle-trochlear groove (TT-TG) distance using CT is a reliable measure and considered the gold standard. Using MRI for this purpose has increased, although the reliability of doing so is not well studied. Read More

Ortop Traumatol Rehabil 2011 Nov-Dec;13(6):607-15

Department of Orthopaedic and Trauma Surgery, Regional Hospital No. 2, Rzeszów. or to pik@pocz ta.onet.pl

Chronic patellar tendon rupture is a rare injury whose treatment poses technical difficulties. Surgical repair is mandatory to restore the extensor mechanism of the knee. Many different surgical methods of patellar tendon reconstruction have been described. Read More

Rev Med Suisse 2011 Aug;7(304):1544-8

Service de chirurgie orthopédique et traumatologie de I'appareil moteur, Departement de chirurgie, HUG, 1211 Geneve 14.

Knee extensor mechanism is composed of the quadriceps and its tendon, patella and patellar tendon. Rupture of either the quadriceps or patellar tendon, or of the patella itself, lead to a disruption of the knee extensor mechanism. Clinical examination reveals an inability to actively extend the knee. Read More

Am J Sports Med 2011 Nov 2;39(11):2436-40. Epub 2011 Aug 2.

Steadman Hawkins Clinic–Denver, 8200 East Belleview Avenue #615, Greenwood Village, CO 80111, USA.

Background: Although knee injuries are common among professional football players, ruptures of the patellar tendon are relatively rare. Predisposing factors, mechanisms of injury, treatment guidelines, and recovery expectations are not well established in high-level athletes.

Hypothesis: Professional football players with isolated rupture of the patellar tendon treated with timely surgical repair will return to their sport. Read More

Scand J Med Sci Sports 2011 Dec 2;21(6):e405-11. Epub 2011 Jun 2.

School of Physiotherapy, Faculty of Health Sciences, La Trobe University, Melbourne, Victoria, Australia.

Patellar tendinopathy (PT) is one of the most common overuse injuries of the knee. Recent reports indicate that increased body mass is frequently associated with tendinopathy, not only biomechanically but biochemically. Abnormalities of other structures within the knee extensor mechanism [patellofemoral joint (PFJ) alignment and patellar tendon length] that can directly influence the strain distribution of the patellar tendon are inconsistently implicated in PT. Read More

Br J Sports Med 2011 Feb 21;45(2):140-6. Epub 2010 Oct 21.

Department of Radiology, University of British Columbia and University of British Columbia, Koerner Pavilion, UBC Hospital, 2211 Wesbrook Mall, Vancouver, British Columbia V6T 2B5, Canada.

At the end of this article, the reader should be able to (1) recognise normal anatomy and anatomical variants of the extensor mechanism of the knee on various imaging modalities, including plain film, ultrasound and MRI; (2) diagnose a broad spectrum of EM injuries in adult and paediatric patients including patellar and quadriceps tendinopathy, Osgood-Schlatter disease, Sindig-Larsen-Johansson syndrome, chondromalacia patellae and patellar fractures on various imaging modalities; and (3) appreciate the important role of imaging in the diagnosis of musculoskeletal injuries. Read More

Clin Anat 2010 Jul;23(5):586-92

Gait Laboratory, Central Remedial Clinic, Clontard, Dublin 3, Ireland.

Failure of the knee extensor mechanism is a potentially disastrous complication of diplegic cerebral palsy and if left undiagnosed may lead to a cessation of independent walking. The disruption of the extensor mechanism usually occurs through or distal to the patella. The aim of this article is to describe the knee kinematic pattern associated with such knee pathology. Read More

J Knee Surg 2009 Oct;22(4):378-81

Department of General and Trauma Surgery, Saint Elisabeth Hospital, Hilvarenbeekseweg 60, 5022 GC Tilburg, The Netherlands.

Rupture of the knee extensor mechanism after previous patellectomy is rare. A treatment protocol therefore is not available. This article presents a new and easy technique using a gracilis-semitendinosus tendon autograft for successful reconstruction of a ruptured knee extensor mechanism after previous patellectomy. Read More

Semin Musculoskelet Radiol 2009 Dec 4;13(4):384-401. Epub 2009 Nov 4.

Inst. f. CT & MRI at Schillerpark, Linz, Austria.

Sports injuries of the knee involving the extensor mechanism are common. Specific conditions additionally affect the extensor mechanism in adolescents during growth and maturation, and in older patients as a result of degeneration. Prior to the advent of magnetic resonance (MR) imaging, the specific anatomical-pathological cause of anterior knee pain was often uncertain, with diagnosis limited to clinical examination and conventional radiographic assessment. Read More