Patellar tendinosis (Jumper \200\231s knee) Patellar tendinosis is characterized by pain ca used by chronic overload of the knee extensor mechanism. This is a common condition seen in athletes that participate in jumping sports and it usually occurs bilaterally. Contrary to initial beliefs, it is not an in \202 ammatory process; tendinosis is a degenerative chan ge or failed healing, with no histo- logical evidence of in \202 ammation. An alternate hy pothesis is that the tendinosis is an adaptive process to the loads within the patellar ten don. \200 Examination Tenderness at site may be present, but an absence does not rule out lesions. Sw elling is invariably not seen. Resisted activation of muscle/tendon, which inserts at the s ite may reproduce pain. Investigations Ultrasound (US) and MR have recognized patterns in some cases with high sign al (osteitis) under entheseal attach- ment in bone typical. Other traumatic lesions should be excluded. There is patellar tendon pain most commonly at its proximal insertion exacerbated by jumpin g or hill running. Dispositions include: \200 intrinsic - ligamentous laxity, increase Q-angle, patella height, and gender; extrinsic - f requency of training, level of performance, hardness of underground. Treatment Topical NSAID gel and judicious glucocorticoid injection should be considered. If part of a wider condition (SpA) consideration of immunosuppressing the disease is impor- t ant (e.g. sulphasalazine). There is tenderness of the patellar tendon with the knee in full extension, but minimal ten derness when it is \202 exed and the tendon is taught. Differential diagnosis is Osgood \200\223Schlatter \200\231s disease; Sinding \200\223Larsen \200\223Johansson Disease; enth esitis (SpAs). Prepatella bursitis Bursae surrounding the knee are susceptible to in \202 amma- tory resp onse either from direct or indirect trauma or can CHAPTER 5 Regional musculoskeletal anatomy and conditions 179 Synovial plica syndrome Plicae are folds of synovial membrane that divide the knee into dif ferent compartments during embryonic develop- ment. Incomplete degeneration results in remn ant plicae. Medial plica pathology is the most common form. There is repeated trauma/irrita tion as the plica rubs over the femo- ral condyle leads to in \202 ammation and \201 bro sis. Reduced plica elasticity causes impingement of the patella or femo- ral condyle and we ar of articular cartilage. Classically, patients may describe symptoms of snapping, popping , crepitus, or pain at particular degrees of \202 exion. \200 become in \202 amed spontaneously particularly from crystal- induced in \202 ammation. Th e prepatella bursa is the most commonly affected bursa. It is commonly caused by acute inju ry, such as a direct fall onto the knee, or from minor repetitive injury, hence, the monike r of \200\230housemaid \200\231s knee \200\231. It can also represent gout or an acute man ifestation of calcium pyrophosphate dihydrate disease (CPPDD; \200\230pseu- dogout \200 \231). Pyogenic bursitis is common, especially in chil- dren with the most common pathogen being Staphylococ- cus aureus. \200 A severely swollen prepatellar bursa may be mistaken for septic arthritis. Opening the join t in this case would result in a septic joint. Findings include swelling anterior to the pa tella with erythema and associated with pain in the acute phase or quiescent if chronic. Fl exion and extension are usually minimally restricted. Management: rest and NSAIDs in the ac ute phase. Aspiration and injection of steroid and local anesthetic; \202 uid to be sent for polarized light microscopy (?gout or pyrophosphate crystals). Traumatic bursitis will o ften respond to aspiration, steroid injection and compressive dressing. Unresponsiveness to conservative management is treated with surgical incision and drainage and complete excisi on of the bursa. Examination reveals joint line tenderness or tenderness on direct palpation of the plica, w hilst \202 exing and extending the knee. The MPP test, as devised by Kim et al. is said t o be a sensitive method for examination and diagnosing medial patellar plica pathology. Ess entially the condition is a diagnosis of exclusion. Differential diagnosis includes: \200 \200 \200 \200 Anterior knee pain in the absence of other causes may be attributed t o plica, but presence of plica itself does not imply pathology. MR can rule out most other causes of pain, such as meniscal tears. Arthroscopy may help con \201 rm diagnosis and tre at problem. Conservative management includes rest and NSAIDs. Physiotherapy for improved qu adriceps strengthening and \202 exibility. Arthroscopic resection is reserved for those w ith recalcitrant symptoms. \200 \200 meniscus tear; fat pad or synovial fringe impingement; localized synovitis; early patellofe moral degenerative (OA). Infra-patellar bursitis or ( \200\230Clergy \200\231s knee \200\231) Small bursae located b etween the patellar ligament and the skin (infrapatellar bursa), and between the ligament a nd the tibial surface (deep prepatellar bursa). \200 \200 There is pain inferior to the lower pole of the patella associated with kneeling or direct pressure. There may also be associated swelling in the area. Management is along the same l ines as pre-patellar bursitis. Differential diagnosis: patellar tendinosis; \200 fat pad impingement syndrome; \200 enthesitis in SpAs. \200 Iliotibial band syndrome (ITBS) Common over-use injury of the lateral aspect of the knee se en particularly in runners, cyclists and endurance sports. \200 Patients describe pain over the lateral femoral condyle caused by friction of the iliotibia l tract sliding over the condyle. Pain is caused by either direct attrition of the ITB or i n \202 ammation of the interposing bursa. Onset of pain usually occurs some time after exe rcise has commenced. The patient may complain of grating over the area secondary to a chron ically in \202 amed ITB bursa. Genu varum or over-pronation of the feet predis- poses to d eveloping ITBS. There is tenderness where the ITB slides over the femoral condyle and/or at its insertion into the lateral proximal tibia (Gerdy \200\231s tubercule). Diagnosis is ma de from a good history and examination. Con \201 rmation is done with ultrasound or MR. Di fferential diagnosis: lateral meniscal tear; \200 discoid lateral meniscus; \200 poplit eus tendonitis; \200 patellofemoral pain syndrome. \200 Non-operative management includ es stretching, tissue massage, orthosis and glucocorticoid injection (under image guidance) . In chronic cases excision of the bursa or surgical tenotomy may relieve symptoms after a diag- nostic arthroscopy has ruled out other pathology. Anserine bursitis Pes anserinus is the common insertion for sartorius, gracilis and semiten dinosus tendons at the medial proximal tibia. The bursa lies between this and the tibial su rface. \200 In \202 ammation of the bursa causes pain along the medial aspect of the knee and tenderne ss 3 \200\2234 cm (2 \201 nger- breadths) below the joint line. Anserine bursitis is comm on in physically active individu- als and is attributed to tight hamstring tendons. It is a diagnosis of exclusion. An injection of local anesthetic and steroid helps con \201 rm di agnosis and treat symptoms simultaneously. Long-term management is with focused physiothera py. Differential diagnosis: \200 \200 \200 \200 \200 \200 \200 \200 medial collateral strain; meniscal tear; articular cartilage damage; proximal tibial stress fracture; Osgood \200\223Schlatter disease; synovial plica syndrome; enthesitis. THE KNEE: REGIONAL MUSCULOSKELETAL CONDITIONS 180 Osgood \200\223Schlatter \200\231s syndrome (OSS) Partial avulsion of the tibial tuberosity from its growth plate secondary to repetitive tensile stresses. \200 giving way and clicking. Meniscal injuries may be associated with ACL or collateral ligamen t injury. Periphery tears may also be associated with synovial cysts expanding through the joint capsule. History re \202 ects gradual onset of activity-related pain situated in region of the tibi al tuberosity. Mostly occurs in athletic adolescent boys between the ages of 12 and 15 year s. It can be bilateral in 20 \200\22330% of cases. There is local swelling and tenderness o f the tibial tuber- osity. Pain is reproduced by direct pressure on the tibial prominence a nd pushing off actions. In the adult there may be a permanent prominence of the tibial tube rosity. OSS is a clinical diagnosis. The ossi \201 cation center of the tibial tuberosity appears around 11 years of age, hence, radiographs will not be very useful for diagnosis pr ior to this. In the adolescent, radiographs may demonstrate a separation of the ossi \201 cation center of the tibial tuber- osity from the proximal tibia in the early stages and fr agmentation in the later stages. Radiographs are useful to rule out tibial tuberosity avuls ion, infection or tumor. MR may be useful in the future for staging and prognostication of OSS. Mild cases can be due to enthesitis, which should be considered in those with psoriasi s, juvenile SpA or JAS or enthesitis-related JIA. Following an acute phase most symptoms sp ontaneously subside over a 12 \200\22324-month period. Treat with rest, ice, and NSAIDs in the acute phase. Activity modi \201 cation along with focused physical therapy plays a cru cial role in managing chronic OSS. In 10%, symptoms remain unabated despite conservative ma nagement. In these rare cases surgical intervention may play a part. Examination An effusion is usually present. Joint line tenderness (palpa- tion with the kne e \202 exed at 90 ) and pain on squatting are highly sensitive tests for meniscal injury . McMurray \200\231s test is positive when pain is reproduced or a clunk is felt as the kne e is \202 exed and rotated (See Plate 2). A new bedside test, the Thessaly test, is sugge sted to be a more accurate method of diagnosing meniscal injury. (See Figure 5.36). Investigation and diagnosis MR scan is the investigation of choice demonstrating the anatom y of the tear. If MR is contra-indicated then an arthrogram may be used to illustrate the l esion. Management Depends on severity of the tear and patient symptoms. Conservative management ma y be appropriate for small or degenerative tears with minimal symptoms. If symptoms are per sistent or severe, then arthroscopy is done for par- tial meniscectomy or meniscal repair. The removal of part of or the entire meniscus predisposes the joint to increase wear rate o f articular cartilage. Differential diagnosis \200 \200 \200 ACL tear. Articular cartilage damage. Osteochondritis dissecans. Differential diagnosis: of anterior knee pain \200 \200 Osgood Schlatter \200\231s Syndrome (OSS). Sinding \200\223Larsen \200\223Johansson syndrom e: similar mecha- nism to OSS, but involving inferior pole of patella. Hoffa \200\231s/ante rior fat pad syndrome. Avulsion fracture of tibial tubercle. Synovial plica injury. Patella r tendonosis. Enthesitis inferior patella pole or tibial tubercle (e.g. AS, PsA, JSpA/JAS). Proximal tibial periostitis. Tumor. \200 \200 \200 \200 Figure 5.36 Thessaly test: examiner-supported weight-bearing rotation with 20 of knee \202 exion. A positive test reproduces pain from meniscus tear. \200 Collateral ligament injury Injuries to the medial and lateral collateral ligaments occur as a result of a valgus or varus stress, respectively, of the partially \202 exed knee. Inj ury may occur from a non-contact or contact mechanism. The different grades of ligament inj ury are described: \200 Meniscal injuries Acute meniscal tears occur when shear forces generated from \202 exion, compression and rotation of the knee ex- ceeds the menisci ability to resist the force. At tachment of the outer border of the medial meniscus to the capsule means that it is less mo bile making it more susceptible to injury. In the older population degenerative tears occur spontaneously usually without a seditious event. There are different types of meniscal tea rs (see Figure 5.36). Grade I: local tenderness, but usually no swelling. Pain is reproduced when the ligament is put under stress, but there is no laxity. Grade II: marked tenderness and sometimes-locali zed swelling. There is some laxity on straining but there is a distinct endpoint. Grade III : complete tear of the ligament \201 bres associ- ated with pain, swelling, and feeling o f instability. Complete tear of the MCL may be associated with ACL injury and more commonly with lateral meniscus tear (valgus strain causing compression of lateral compartment). Gra de III tear of the LCL usually involves History The patient may describe a twisting injury to the knee with the foot \201 xed. Th e degree and onset of pain is variable and symptoms may be delayed for over 24 h. Other sym ptoms include restricted range of movement, intermittent locking, CHAPTER 5 Regional musculoskeletal anatomy and conditions 181 the posterolateral complex. This is associated with rotatory instability and requires surgi cal repair. Investigation and diagnosis Diagnosis is clinical, but plain radiographs may show associ- a ted bony injury. MRI is helpful in ruling out other soft tissue injury. Management MCL injuries routinely are treated conservatively. Patients with grade III injur y have been shown to return to sport, as well as those treated surgically. A stabilizing br ace is used during the rehabilitation period. Grade I and II LCL injuries are treated conse rvatively but grade III injuries are treated surgically due to rotational instability. Differential diagnosis \200 Anserine bursitis. \200 Patellofemoral syndrome. \200 Tib ial plateau fracture. Figure 5.37 Lachmann test. Excessive translation of tibia (upward) from femur suggests ACL de \201 ciency. Anterior cruciate ligament Injury ACL rupture is relatively common particularly in sports i nvolving pivoting and cutting maneuvers. ACL injury may occur in isolation or in combinatio n with other injuries particularly meniscal tears. There is a higher incidence of ACL ruptu re in female athletes when compared with males doing similar activities. History The majority of ACL tears occur in a non-contact situation when an athlete is landi ng from a jump, pivoting, or decel- erating. An audible \200\230pop \200\231 or feeling th at something came out then relocated is described. There is pain limiting any further actio n and swelling develops over hours. Examination In the acute presentation there is swelling of the joint with restricted range of movement. There is widespread ten- derness. With subsidence of pain examination will dem on- strate a positive Lachman \200\231s test (most sensitive and speci \201 c test). (See Figure 5.37). The pivot-shift test is diagnostic of ACL de \201 ciency but it is dif \201 cult to perform and it is depen- dent on the ability of the patient to relax. An anterior drawer test is usually positive, but it is the least sensitive of examinations (See Plate 3 ). Figure 5.38 MR sagittal image showing ACL tear. present to show that ACL reconstruction will prevent progression to degenerative joint dise ase. Investigations and diagnosis Plain radiographs should be done to reveal any associated bony injury, such as an avulsion fracture of tibial spine, or a \200\230Segond \200\231 fractu re (anterolateral capsule avulsion). These are pathognomonic of an ACL rupture. If in doubt an MR scan is done to con \201 rm the diagnosis. (See Figure 5.38). Posterior cruciate ligament injury PCL tears are rarer than ACL injuries and are usually ca used by signi \201 cant direct trauma. Injuries usually occur from direct trauma to the ti bia whilst the knee is in a \202 exed position or from a forced hyper \202 exion or hype rextension injury. The posterior drawer test is positive. Investigations are the same for A CL injuries. Management Treatment is dependent on several factors and each patient is considered individ ually on the merits of conser- vative and surgical intervention: \200 \200 \200 Management Isolated PCL tears are treated conservatively with most patients maintaining ade quate function. Bony avulsion from the tibial insertion, chronic PCL-related instability, o r combination injuries should be surgically repaired. Patient age: more likely to operate if young. Degree of instability. Associated abnormaliti es (MCL or meniscal tear) \200\223 poorer prognosis if not repaired. Patient \200\231s lev el of activity \200\223 level of demands placed on the knee (occupation, sports). Baker \200\231s (popliteal) cyst (See Figure 5.39) A cyst developing in the popliteal fossa is usually formed from the egress of \202 uid from the knee joint through a normal commu nication to the bursa between semimebra- nosus and medial head of gastrocnemius. It can als o form from a herniation of the synovium through the joint capsule. Non-surgical management involves physical rehabilitation, the use of braces, and avoidance of aggravating activities. ACL rupture is associated with increased risk of develop- ment o f osteoarthritis, but there is little evidence at THE KNEE: REGIONAL MUSCULOSKELETAL CONDITIONS 182 Figure 5.39 Two MR images of popliteal cyst formation. The image on the left is a reconstru cted sagittal section from subtraction of identical T1-weighted images taken before and aft er contrast enhancement. The contrast highlights the complexity of popliteal cyst con \201 guration (as well as showing the extent of suprapatellar pouch synovium). The right-hand i mage (different patient) shows how large popliteal cysts can be (lateral part of the knee, sagittal section). In adults it is usually associated with an intra-articular pa- thology. In association with inflammatory arthritis popliteal cysts can be extensive and lie serpiginously around popli teal structures including the popliteal artery. The prevalence of Baker \200\231s cysts in children is low (roughly 6.3% in asymptomatic children undergoing MR of the knee) and it us ually does not communicate with the joint or have an associated intra-articular pathology. Examination Typically a smooth, painless, non-pulsatile mass is located below the joint lin e in the popliteal fossa. It is tense with knee in extension. Investigation and diagnosis Knee radiograph to characterize joint disease and detect soft t issue mass. US con \201 rms whether the popliteal mass is a pure cystic structure or a com plex cyst and/or solid mass with associated vascularity. MR scan demonstrates intra- articu lar pathology or illustrates any soft tissue pathology, such as rhabdomyosarcoma or pigment ed villonodular sy- novitis. It may also be used to identify the communication between the cyst and the joint cavity. Management In children, most cysts spontaneously resolve in 10 \200\22320 months. In protra cted cases, aspiration and injection with steroid may resolve cysts (note that there is no communication with the joint unlike in adults). In adults, the intra-articular pathology sh ould be addressed (e.g. intra-articular \202 uid aspirated and steroid injected) and, wit h time, the cyst should then spontaneously regress. The most common complication of a Baker \200\231s cyst is rupture into the proximal gastrocnemius causing a pseudothrombophlebitis syn- drome typically causing swelling and discomfort/pain of the lower leg. Skin can be er ythematous. This clinically presents similarly to a deep vein thrombosis (DVT). Figure 5.40 Oblique tear in the posterior medial meniscus. See the oblique white (high MR s ignal) line through the dark wedge shape (the cross sectional appearance of the meniscus). Differential diagnosis \200 \200 \200 Vascular masses (aneurysm or DVT). Soft tissue tumors. Meniscal cysts; cellulitis. CHAPTER 5 Regional musculoskeletal anatomy and conditions 183 Further reading De Maeseneer M, Debaere C, Desprechins B, Osteaux M. Popliteal cysts in chi ldren: prevalence, appearance and associated \201 ndings at MR imaging. Pediatr Radiol 19 99; 29(8): 605 \200\2239. Kim SJ, Jeong JH, Cheon YM, Ryu SW. MPP test in the diagnosis of patellar plica syndrome. Arthroscopy 2004; 20: 1101 \200\2233. Kim SJ, Lee DH, Kim TE. The relationship between the MPP test and arthroscopically found me dial patellar plica pathology. Arthroscopy 2007; 12: 1303 \200\2238. Dupont JY. Synovial plicae of the knee. Controversies and review. Kumar D, Alvand A, Beacon JP. Impingement of infrapatellar fat pad (Hoffa \200\231s disease ): results of high-portal arthroscopic resection. Arthroscopy. 2007; 11: 1180 \200\2236. Clin Sports Med 1997; 16: 87 \200\223122 Gholve PA, Sher DM, Khakharia S, Widmann RF, Green DW. Osgood Schlatter syndrome. Curr Opin Pediat 2007; 19: 44 \200\22350. Miller TT, Staron RB, Koenigsberg T. MR imaging of Baker cysts: association with internal d erangement, effusion, and degenerative arthropathy. Radiology 1996; 201: 247 \200\22350. Hamilton B, Purdam C. Patellar tendinosis as an adaptive process: a new hypothesis. Br J Sports Med 2004; 38: 758 \200\22361. Hirano A, Fukubayashi T, Ishii T, Ochiai N. Magnetic resonance imag- ing of Osgood \200\223 Schlatter disease: the course of the disease. Skeletal Radiol 2002; 31: 334 \200\22342. Scholten RJPM, Opstelten W, van der Plas CG, Bijl D, Deville WLJM, Bouter LM. Accuracy of p hysical diagnostic tests for assessing ruptures of the anterior cruciate ligament: a meta-a nalysis. J Fam Pract 2003; 52: 689 \200\22394. James SLJ, Ali K, Pocock C, et al. Ultrasound guided dry needling and autologous blood inje ction for patellar tendinosis. Br J Sports Med 2007; 41: 518 \200\22321. Shelbourne KD, Davis TJ, Patel DV. The natural history of acute isolated nonoperatively tre ated posterior cruciate ligament injuries. A prospective study. Am J Sports Med 1999; 27: 2 76 \200\22383. Karachalios T, Hantes M, Zibis AH, et al. Diagnostic accuracy of a new clinical test (the T hessaly test) for early detection of meniscal tears. J Bone Jt Surg Am 2005; 87: 955 \200 \22362. Khan KM, Cook JL, Bonar F, et al. Histopathology of common tend- inopathies. Update and imp lications for clinical management. Sports Med 1999; 27: 393 \200\223408.