Management Infection must be excluded. Treatment is usually conservative and consists of re st, NSAIDs, and stretching of the relevant muscles. Glucocorticoid and local anesthetic inj ection under imaging guidance can be very useful. Osteonecrosis (ischaemic necrosis/avascular necrosis) of the femoral head See also p. 433. History \200 \200 Lateral hip pain \200 \200 \200 Common in 30 \200\22350-year-olds. Need to identify the child with Legg \200\223Calve \200 \223Perthes syndrome (idiopathic avascular osteonecrosis of the capital femoral epiphysis o f the femoral head). Identify possible causes \200\223 see Table on p. 433. Hip/groin pain with possible radiation to knee. Trochanteric bursitis. Guteus medius insertional tendonitis/tear. Nerve compression (common ly lateral femoral cuta- neous nerve). Referred pain from lumbar spine. \200 Posterior hip pain \200 \200 \200 \200 Examination \200 \200 Sacroiliitis. Ischiogluteal bursitis. Referred pain from lumbar spine. Vascular insuf \201 ciency (Leriche \200\231s syndrome). May be unremarkable if early stages. Antalgic gait with restricted range of motion (especia lly internal rotation). In late stages, signi \201 cant limb length discrepancy with restr icted movement and muscle wasting. Imaging and diagnosis \200 Bursitis There are multiple bursae located around the hip, in and around areas subject to f riction (between muscle and a bony prominence). Bursitis is commonly an over-use friction p henomenon, but a history of trauma (traumatic bursitis) and infection must be excluded. Radiographs: degenerative changes, sclerosis, subchondral lucency, collapse of femoral head . See Figure 5.29. MR: highly sensitive in showing subchondral oedema. Bone scintigraphy: l ess sensitive than MR in early stages, phase of disease associated with patterns of photopa enia and excess tracer localization. \200 Trochanteric bursitis A common condition in athletes, but also associated with the spondyla rthropathies and obesity. It will cause a well localized tenderness to the superolateral as pect of the greater trochanter. Sometimes there may be associated referred pain to the late ral thigh. Hip movement is unaffected except for internal rotation of the hip. Management \200 Conservative measures: limited weight bearing and/or immobilization. Recent studies suggest a role for bisphosphonates in delaying femoral head collapse. Surgical management include core decompression of femoral head or free vascularized \201 bular grafting in early stag es of the disease. Good medium term results have been reported (Urbaniak et al. 1995). Adva nced diseases will inevitably require surgical intervention, in particular hip joint replac ement. Resurfacing hip arthroplasty is gaining increasing popularity in the treatment of pa inful arthropathy in younger patients. In general, there is 70 \200\22380% chance of femora l head collapse in patients with con \201 rmed osteonecrosis. Iliopsoas bursitis This bursa separates the hip joint from the iliopsoas tendon and may com municate with the joint. More common in sports-related injury requiring extensive hip flexi on. Causes deep anterior groin and thigh pain, and may present with large soft tissue swell ing lateral to the femoral triangle. Pain is exacerbated with hip extension and resisted hi p \202 exion. Ischiogluteal bursitis This is commonly traumatic in nature, occurring after blows to the i schial tuberosity. There is localized tenderness, worse with sitting or lying on it. Someti mes it is hard to distinguish from hamstring injuries. CHAPTER 5 Regional musculoskeletal anatomy and conditions 169 MR arthrogram has been reported to be a useful tool with high accuracy diagnostic rates. (C zerny et al. 1996). Hip arthroscopy has become the gold standard for diagnostic and therape utic purposes. It allows a comprehensive evaluation of labral anatomy. Management \200 Conservative bed-rest and period of immobilization may be helpful initially, but there are no long-term outcome studies to support such conservative measures. Arthroscopic debridemen t of the lesion has been shown to be successful. Hip arthroscopy is a technically challengi ng procedure, but in the hands of an experienced surgeon, can produce good outcome. Femoroacetabular impingement (FAI) This is the abutment of femoral neck on to the anterior rim of the acetabulum. It is increasingly recognized as a cause of signi \201 cant hip/gro in pain, and strongly implicated as a cause of secondary OA. FAI can be either cam (aspherical contoured femoral head abutting against acetabular rim) o r pincer (linear abut- ment of femoral head-neck junction and the acetabular rim) impingeme nt. Cam impingement has been associated with conditions causing a decrease in femoral head-neck offset. \200 Slipped capital femoral epiphysis (S CFE). \200 Legg \200\223Calve \200\223Perthes syndrome. \200 Acetabular rim syndrome (a cetabular dysplasia). \200 Malunited femoral neck fractures. Pincer-type impingements are associated with conditions producing over-coverage by anterior acetabular rim: \200 \200 \200 Figure 5.29 Osteonecrosis of the femoral head Ficat stage 3. Ficat stages: Stage 1-2 = anox ia, bone necrosis, microfractures; Stage 3 = segmental collapse; Stage 4 = secondary OA. Acetabular retroversion. Coxa profunda (increased relative acetabular depth). Protrusio ace tabuli. Labral tears Although \201 rst reported in the late 1950s, it is only in recent times tha t acetabular labral tears have become a recognized cause for hip/groin pain. Tears occur mo st commonly in the anterior part of the labrum. History \200 \200 \200 Commonly effects young active adults <50 years old. Anterior groin pain. Labral tears almos t always have co-existing mechanical symptoms (locking, catching, and giving way). Elicit h istory of previous hip disease (SCFE) or surgery. History \200 Mechanical hip pain, with sharp and catching sensation on certain movements, and locking. U sually groin pain, but may be trochanteric. Commonly associated with degenerative disease a nd in athletes. An overwhelming majority of labral tears are associated with structural hip abnormalities. Important to check for acetabular dysplasia and femoroacetabular impingemen t (FAI). Identify history of minor injuries (e.g. twisting, slipping, falling), posterior h ip dislocation or recent trauma. Examination \200 \200 \200 \200 Limp or positive Trendelenburg test maybe present. Restricted motion - \202 exion and int ernal rotation. Anterior impingement test is almost universally positive. Imaging and diagnosis \200 \200 AP and lateral plain radiographs essential. Identify femoral abnormalities (pistol-grip def ormity, coxa vara and valga) and acetabular abnormalities (os acetbaulare, dysplasia, protr usio acetabuli, and inclination and version of actabulum) MRI is now more commonly used, bu t MR arthrography is becoming the standard investigation. Can help to identify associated l abral tears and chondral damage Examination \200 Hip movement may be unaffected, but may be painful at the extremes. Anterior tear: acute hi p \202 exion with internal rotation and adduction. Posterior tear: hyperextension with ex ternal rotation and abduction. Management \200 Conservative: rest, modi \201 cation of activity and avoiding excessive hip movement. Regu lar NSAIDs. This usually provides temporary relief. Open surgery includes hip dislocation a nd relevant excision osteotomy from the head-neck junction, or resection of the excess acet abular rim causing Imaging and diagnosis \200 Radiographs, CT and MR have not been reliable tools for diagnosis. They are useful for excl uding other hip pathologies. PELVIS, HIP AND GROIN: REGIONAL MUSCULOSKELETAL CONDITIONS 170 the impingement. Any labral tears should be treated with repair or partial resection. Arthr oscopic surgery is becoming popular with favorable results for treatment of FAI. (Sampson 2 005). As well as serving as a diagnostic tool, labral debridement, chondroplasty and burr r esection of osteophytes can be performed arthroscopically. Management \200 Conservative \202 exibility stretching and pelvic muscle strengthening. However, a rotati onal pelvic osteotomy may be necessary in order to delay onset of OA. Osteitis pubis A painful in \202 ammatory process commonly seen in patients with spondylar thropathy and athletes. An infective lesion (osteomyelitis pubis) may present and must be r uled out. History \200 \200 Gradual onset of pain in pubis region. Exercise induced symptoms \200\223 commonly kicking , striding, or pivoting \200\223 in athletes though in \200\230traumatic \200\231 osteiti s, as well as SpA-related lesions pain at rest can occur. Pain often radiating to medial th igh or up to the abdomen. Examination \200 Point tenderness around pubic symphysis often exacerbated if rectus abdominis contracts. Pa inful passive hip abduction. Painful active hip adduction against resistance. \200 (a) Imaging and diagnosis \200 Essential to rule out infection (ESR, CRP, and white cell count may help though low grade a cute phase response can be SpA-related. Biopsy and tissue micoscopy and culture may be need ed. Plain radiographs can show widened symphysis, cystic changes and sclerosis in the acute lesion. Old lesions can present with sclerosis and joint irregularity. Isotope bone scan ( with SPECT) is a sensitive test and will demonstrate increased tracer uptake in the area of the pubic symphysis. MR can show in \202 ammatory changes in the bone (e.g. subenthesial osteitis in SpAs) and is increasingly becoming a useful diagnostic tool (Karlsson et al. 19 97) (b) Management \200 \200 Figure 5.30 (a) T1 sequence MRI of the hip showing osteonecrosis in the classic superior se gment of the femoral head with a hypointense (dark) band outlining the interior extent of t he lesion; (b) T2 sequence MRI of the hip showing the hyperintense bright (white) band alon g the inner rim of the zone of osteonecrosis (dark band noted in (a)). This represents the double-line sign that is diagnostic of osteonecrosis. Treatment begins with rest and NSAIDs. Physiotherapy to correct muscular imbalance and maxi mize functional pelvic stability. Use of glucocorticoid injection is controversial. If ther e is extensive osteitis then use of intravenous bisphosphonate can be helpful. If there is substantial pelvic instability on weight bearing (Stork-view) radiographs, surgery may be i ndicated (plating or bone grafting). \200 Acetabular rim syndrome (Klaue et al. 1991) History \200 \200 \200 Usually young active patients (18 \200\22335 years old). Sharp groin pain. Hip locking, cat ching or giving way. Nerve entrapment lesions Presents with pain and numbness in the affected nerve distribution . Examination \200 \200 \200 Lateral femoral cutaneous nerve (meralgia paraesthetica) Commonly due to mechanical entrapm ent (e.g. tight pants or weight gain) or anatomical entrapment of nerve in origin of the in guinal ligament at the anterior superior iliac spine. Paraesthesia along lateral thigh. (Se e Fig.5.31). May be normal. Positive anterior impingement test. Positive apprehension test (extension an d external rotation of the hip gives the sensation of instability). Ilioinguinal nerve Can be implicated following surgery (appendicectomy or herniorrhaphy), b ut also common in athletes following direct trauma or following intensive training of the a bdominal musculature. Paraesthesia along upper medial thigh and mons pubis. Imaging and diagnosis \200 \200 \200 Radiographic appearances constitute the gold standard. Incongruent shallow acetabulum. Cong ruent acetabulum with poor femoral head coverage ( \200\230short roof \200\231). CHAPTER 5 Regional musculoskeletal anatomy and conditions 171 Common sites of SpA-related enthesitis around the hip \200 \200 \200 Posterior superior iliac spine. Anterior superior iliac spine. Greater trochanter: often mi sdiagnosed as bursitis. US or MR imaging can discriminate in \202 ammatory lesions from te nderness associated with referred lumbosacral pain. Lesser trochanter: useful place to see erosive enthesitis as a diagnostic aid if SpA diagnosis uncer- tain. Adductor tubercle: dif \201 cult to tell sometimes from osteitis pubis. Both lesions can occur in same patient. 10cm LCN emerges 10cm below ASIS Adductor longus Most frequently injured groin muscle-tendon unit. Primarily affecting footb all and hockey players, there are associated extrinsic factors (including training methods and types of activity) and intrinsic factors, such as malalignment, muscle strength, and as ymmetrical muscular \202 exibility of the adductor group. (Renstrom, 1992). There is well localized tenderness over the muscle insertion on the lower pubic ramus. Pass ive stretching of adductors or resisted adduction elicits pain. Figure 5.31 Usual site of entrapment of lateral cutaneous nerve, and site for injection, ju st above femoral neck 10cm below anterior superior iliac spine. Rectus Femoris This muscle tendon unit can be damaged at its origin on the anterior inferio r iliac spine, often associated with sprinters and in footballers. Pain is elicited with pa lpation along the muscles insertion and with resisted hip \202 exion. Treatment Rest, NSAIDs, altered training methods. Injection of local anesthetic can relieve symptoms temporarily, but helps in diagnosis too. Rarely, surgical release or neurolysis m ay be necessary if pain is refractory. (Westlin 1997) Rectus abdominis Repeated hip \202 exion, leg raises and abdominal \202 exion may resul t in rectus abdominis injury. There is tenderness of the upper pubic ramus and lower abdome n. Pain can be repro- duced with patients contracting their abdomen. Tendonitis and enthesitis around the pelvis Tendonitis arises secondary either due to an ac ute injury (due to the eccentric contraction of relevant muscle), chronic over-use injury o r as part of an in \202 ammatory condition, most usually a SpA condition. Imaging and diagnosis Plain radiographs are usually normal, but may demonstrate other bony lesions (e.g. degenerative changes or associated bony avulsion fragment), chronic enthesiti s or calci \201 ed tendinosis in chronic situations. The \200\230over-use theory \200\231 considers that a tendon is sub- jected to persistent loads resulting in intra-tendinous partial rupture (micro-trauma) of the \201 brils and t endon injury. (Curwin et al. 1984). Microscopically, with micro-trauma there is non-in \202 ammatory collagen degeneration with \201 bre disorientation resulting in abnormal te ndon function. Hence the term tendinopathy has been advocated for con- ditions arising from over-use. (Maffulli et al. 1998). US and MR may detect more subtle tendon injury or enthesitis in \202 ammation. Management The primary aim in treating tendonitis and enthesitis is to relieve pain. As suc h, the \201 rst would be to avoid strenuous and painful activities. Often, simple measure s, such as rest, icing, and NSAIDs will relieve symptoms, followed by gentle stretching and physiotherapy regimen. Ultimately, patients who are normally very active will require a pe riod of rehabilitation to normal strength, range of movement, endurance and activity. Enthesitides occur commonly around the pelvis and groin in patients with SpA. Pain and tend erness can be lo- calized or quite diffuse and can mimic tendonitis. Iliopsoas tendonitis History of insidious onset of anterior hip pain as a result of repetit ive hip \202 exion. In the acute circumstance, there is an onset of sudden pain caused by \202 exion against resistance. Pain may be reproducible on certain hip \202 exion move - ments especially in runners and kickers. Injection of local anesthetic and glucocorticoid has a role in relieving symptoms, in addit ion to diagnostic values. Surgical intervention, although uncommon, can be invoked in certa in refractory cases of traumatic tendonitis. Proce- dures include tenotomy, and partial or complete release of the tendon. There may be localized tenderness on palpation of lesser trochanteric region under the glut eal fold, and there may be associated painful snapping in the groin as the ten- don moves m edially to laterally across the femoral head during hip movements from \202 exion to exte nsion, respec- tively. Resisted hip \202 exion with palpation of the psoas muscle at its insertion point will also elicit pain. Further reading Curwin S, Stanish WD. Tendinitis: its etiology and treatment. Lexington: Collamore Press/DC Heath and Company, 1984. PELVIS, HIP AND GROIN: REGIONAL MUSCULOSKELETAL CONDITIONS 172 Maffulli N, Khan KM, Puddu G. Over-use tendon conditions:time to Czerny C, Hofmann S, Neuhold A, Tschauner C, Engel A, Recht MP et al. Lesions of the acetab ular labrum: accuracy of MR imaging and MR arthrography in detection and staging. Radiology 1996; 200: 225 \200\22330. change a confusing terminology. Arthroscopy 1998; 14: 840 \200\2233. Renstrom PAHF. Tendon and muscle injuries in the groin area. Clin Sports Med 1992; 11: 815 \200\22331. Hungerford MW, Mont MA, Scott R, Fiore C, Hungerford DS, Krackow KA. Surface replacement he miarthroplasty for the treatment of osteonecrosis of the femoral head. J Bone Jt Surg Am 19 98; 80: 656 \200\22364. Sampson TG. Arthroscopic treatment of femoroacetabular impingement. Techn Orthopaed 2005; 20: 56 \200\22362. Santori N, Villar RN. Acetabular labral tears:results of arthroscopic partial limbectomy. Arthroscopy 2000; 16: 11 \200\22315. Ito H, Matsuno T, Kaneda K. Prognosis of early stage avascular necrosis of the femoral head . Clin Orthopaed 1999; 358: 149 \200\22357. Johnston CA, Wiley JP, Lindsay DM, Wiseman DA. Iliopsoas bursitis Urbaniak JR. Coogan PG. Gunneson EB. Nunley JA. Treatment of osteonecrosis of femoral head with free vascularised \201 bular grafting. A long term follow-up study of one hundred an d three hips. J Bone Jt Surg Am. 1995; 77:681 \200\22394. and tendonitis. Sports Med 1998; 25: 271 \200\22383. Karlsson J, Jerre R. The use of radiography, magnetic resonance, and ultrasound in the diag nosis of hip, pelvis, and groin injuries. Sports Med Arthrosc Rev 1997; 5: 268 \200\22373. Westlin N. Groin pain in athletes from Southern Sweden. Sports Med Arthrosc Rev 1997; 5: 280 \200\2234. Klaue K, Durnin CW, Ganz R. The acetabular rim syndrome. J Bone Jt Surg Br 1991; 73: 423 \200\2239. Lai KA, Shen WJ, Yang CY. The use of alendronate to prevent early collapse of the femoral h ead in patients with nontraumatic osteonecrosis. A randomized clinical study. J Bone Jt Sur g Am 2005; 87: 2155 \200\2239. This page intentionally left blank THE KNEE 174 The knee Regional anatomy The knee is the largest and most complex synovial joint in the body. It is a modi \201 ed hinge (condyloid) joint capable of \202 exion, extension and an element of rotation. through associated ligaments, menisci, \201 brous capsule, and surrounding musculature. Joint capsule The knee joint is enclosed by an incomplete fibrous capsule. Anteriorly, the de \201 ciency is completed by the quadriceps femoris tendon, the patellar ligament, and t en- dinous expansions from the iliotibial band and quadriceps forming the patellar retinacu lum. These form an expand- able anterior knee space that extends above the upper pole of th e patellar as the supra-patellar pouch. It is made up of two separate joints \200\223 the tibiofemoral joint, most commonly referr ed to as the knee joint; and the patellofemoral joint. The two joints are enclosed within t he same synovial cavity in the joint capsule. Bony anatomy Tibiofemoral joint The distal femur, consisting of two condyles, articulates w ith the \202 attened tibial plateau to form the tibiofemoral joint. The femoral condyles are markedly convex and are divided by an intercondylar notch, which accommodates the cruci ate ligaments. The joint capsule is reinforced by expansions of semime- branosus and biceps femoris tendon s, the oblique popliteal ligament and arcuate popliteal ligament, respectively, as well as the medial collateral ligament. Ligaments of the knee joint (See Figure 5.32) Medial/tibial collateral ligament (MCL) The M CL is a broad structure made of two distinct parts: \200 The tibia plateau condyles are oval and slightly convex. They are separated by the intercon dylar eminence, around which the femur rotates and the surrounding intercondylar area to wh ich cruciate ligaments attach. The super \201 cial MCL extends from the medial epicondyle of the femur to the anteromedia l aspect of the proximal tibia. This part is extracapsular and is predominantly responsible for medial joint stability on valgus stressing. The deep MCL attaches to the joint margin reinforcing the joint capsule. It also attaches to the peripheral margin of the medial meni scus. line of capsular attachment patella Lateral/ \201 bular collateral ligament (LCL) The LCL is a distinct cord-like structure ar ising from the lateral femoral epicondyle and attaching to the apex of the \201 bula head . \200 medial meniscus The LCL is separate from the capsule and does not reinforce it. The LCL prevents lateral op ening of the tibia on the femur during varus stressing. popliteus tendon lateral ligament medial ligament Cruciate ligaments (See Figure 5.33) Anteroposterior stability is provided by the two cruci ate ( \200\230cross \200\231) ligaments. They are named anterior and posterior in relation to their attachments to the tibia. Although completely contained within the joint capsule t he cruciates are enveloped with synovium and are thus described as intracapsular, but extra -synovial structures. Anterior cruciate ligament (ACL). The ACL runs in an ante- rior to po sterior direction from its attachment near the front of the tibia plateau to its femoral in sertion at the posterolateral corner of the intercondylar notch. It consists of two distinc t functional bundles: \200 lateral meniscus patellar ligament tibial tuber osity Figure 5.32 Knee joint: anterior view showing capsule attachments and ligaments. Anteromedial \201 bres: tight in \202 exion; limits anterior translation of tibia on fe mur. Posterolateral \201 bres: tight in extension; limits anterior translation and extern al rotation of the tibia. Patellofemoral joint The patella is the largest sesamoid bone in the body. It is suspended within the quadriceps and the patella tendon articulating with the concave anterior aspect (the trochlea groove) of the distal femur. \200 The ACL is an important stabilizer of the knee during pivoting movements. A de \201 cient ACL causes excessive anterior-lateral displacement of the tibia under the femur during acti vities, such as jumping or rapid deceleration. Posterior cruciate ligament (PCL). The PCL a ttaches to the posterior part of the tibial plateau and runs anterosuperi- orly to insert i nto the medial aspect of the intercondylar notch. It restricts anterior translation of the femur on the tibia and prevents hyperextension of the joint. The under-surface of the patella has the thickest articular cartilage in the body indicatin g the signi \201 cant stresses across the joint. Primary function of the patella is to inc rease the lever arm of the quadriceps. The knee is a potentially unstable joint due to the apposing nature of its bony anatomy. Jo int stability is obtained CHAPTER 5 Regional musculoskeletal anatomy and conditions 175 is not a true bursa, but an extension of the joint capsule. The bursae most susceptible to in \202 ammation include: \200 Prepatellar: large bursa interposed between the patella and the skin. Infrapetellar: small bursa located between the skin and patellar tendon. Deep patellar: bursa located between th e tibial tuber- osity and the patellar tendon. It is separated from the synovium by and int erposing fat pad. Pes anserinus: located inferior and medial to the knee joint line. It sep arates the pes anserinus and the tibia. posterior cruciate ligament anterior cruciate ligament Alignment of the knee Joint The normal knee is in slight valgus. The angle between the tibi a and the femur is known as the Q angle. In males this is normally 14 and in females 17 . The Q angle is increased in genu valgum ( \200\230knock knees \200\231) and decreased in ge nu varum ( \200\230bow leg \200\231). Biomechanics and stability of the patellofemoral join t are determined by the length of the patella tendon and the Q angle. interosseous membrane Muscles around the knee joint (Table 5.10) Muscles are responsible for movement and stabili zation of the joint. Reduced muscle tone may predispose to injury and dislocations of the j oint. Figure 5.33 Cruciate ligaments, anterior view. Menisci (See Figure 5.34) The menisci are wedge-shaped semi-lunar cartilages situ- ated bet ween the tibiofemoral joint spaces. The medial meniscus is C-shaped and larger than the lat eral meniscus, which is more circular. \200 femur Menisci consist of fibrocartilage, which gives them distinctive properties from articular c artilage. The medial and lateral menisci are attached at their periphery to the joint capsu le, and centrally, via the ante- rior and posterior horns, to the tibia. The peripheral 10 \200\22330% and anterior and posterior horns are vascularized giving these areas capacity f or repair; otherwise, the rest of the meniscus is avascular. Functions of the menisci inclu de: \200 \200 \200 suprapatellar bursa connecting with synovium quadriceps femoris patella tendon of popliteus prepatellar bursa lateral ligament lateral meniscus shock absorption; load distribution across the joint surface; reduction of contact stress b etween articular surfaces by increasing joint congruity; improve stability of the joint by increasing the concavity of the tibia plateau; joint lubrication and nutrition; prevent syn ovial impingement. deep infrapatellar bursa fibula superficial infra- patellar bursa tibia \200 Figure 5.35 Synovial membrane and bursae of knee. tibial tuberosity lateral meniscus medial meniscus Table 5.10 Prime muscle movers of the knee Movement Muscles Extension Rectus femoris, vastus medialis, vastus lateralis, vastus intermedius (quadriceps muscles) Flexion Semimembranosus, semitendinosus, biceps femoris (hamstring muscles) Sartorius, gracilis, gastrocnemius, adductor magnus lateral ligament ant. and post. cruciate ligaments medial ligament Biceps femoris External rotation of tibia Figure 5.34 Menisci and attachments of cruciate ligaments of left knee viewed from above. Popliteus: initiates internal rotation thus unlocking knee when in full extension Sartorius , gracilis, semitendinosus. The common tendon insertion of these form the pes anserinus Internal rotation of tibia Bursae of the knee joint There are several bursae surrounding the knee joint reduc- ing fri ction between moving structures, such as tendons, bones, ligaments, and skin. The suprapate llar pouch/bursa Lateral aspect knee showing extent of joint and bursae. THE KNEE 176 Further reading Aglietti P, Insall JN, et al. Patellar pain and incongruence: 1: Measuremen ts of Incongruence. Clin Orthopaed Relat Res 1983; 176: 217 \200\22324. Messner K, Gao J. The menisci of the knee joint. Anatomical and functional characteristics, and a rationale for clinical treatment. J Anat 1998; 193: 161 \200\22378. Patel RV, Haddad FS. Technique of knee joint aspiration. Br J Hosp Med (Lond) 2007; 68(6): 100 \200\2231. Amiss AA. Current concepts on anatomy and biomechanics of Rath E, Richmond JC. The menisci: basic science and advances in patellar instability. Sports Med Arthrosc 2007; 15(2): 48 \200\22356. treatment. Br J Sports Med 2000; 34: 252 \200\2237. Ellis H. The applied anatomy of examination of the knee. Br J Hosp Med (Lond) 2007; 68(4): 60 \200\2231. This page intentionally left blank THE KNEE: REGIONAL MUSCULOSKELETAL CONDITIONS 178 The knee: regional musculoskeletal conditions Patellofemoral instability De \201 ned by a predisposition for the patella to sublux or di slocate from its normal articulation, the cause of instability is either primary or seconda ry to a traumatic episode. Women are more prone to primary instability due to increase genu valgum and hence increase Q-angle; greater ligamentous laxity; smaller muscle bulk and sha llow troch- lear groove. \200 Depending on duration of symptoms there may be quad- riceps atrophy. Symptoms are reproduce d on patellar loading. Diagnosis is clinical. Con \201 rmation is made with ultra- sound s can or MR. Plain radiographs, CT or isotope bone scan are only used when diagnosis is in do ubt following initial investigations. The management is to rest from sporting activities an d NSAIDs in the acute stages. Physical therapy to strengthen the quadriceps muscles and str etch the patellar tendon with increasing loads. Patella strapping and soft insoles may help prevent recurrence. Peri-tendinous injections of glucocorticoid, autologous blood injectio n or dry needling of affected using image guidance may resolve recalcitrant symptoms and sh ould be attempted before surgery. Surgical intervention is considered for patients that fai l to respond to non-surgical measures. Patients complain of sensation of the patella dislocating or moving laterally when performi ng certain movements. A history of pain may be due to maltracking of the patella, which is apparent on examination. Lateral push on the patellar, whilst \202 exing the knee causes apprehension. This is a clinical diagnosis. Plain radiographs may reveal evidence of predis posing anatomical abnormalities and osteochondral defects in traumatic dislocations. Acute dislocations are temporarily immobilized following relocation for a short period followed b y rehabilitation. Surgical intervention to correct predisposing factors is reserved for fai led conservative treatment. Enthesitis In \202 ammation and/or microtrauma of entheses around the knee, particularly a t the origin of the patellar tendon (pa- tella inferior pole) and insertion at the tibial t ubercle are relatively common lesions associated with SpAs. Lesions can exist without evide nce of coincident synovial in \202 am- mation in the joint either isolated or in combinati on with entheseal symptoms elsewhere. Other potential sites of pain from enthesitis around the knee include tendon inser- tions at medial and lateral femoral condyles [especially pso riatic arthritis (PsA)], gastrocnemius head origins, pes anserinus and quadriceps attachmen t to the superior patella pole. Fat pad impingement syndrome (Hoffa \200\231s disease) Acute or chronic impingement of the richly innervated infrapatellar fat-pad between the patella and femur during \202 exion a nd extension of the knee. \200 The patient describes a long history of anterior knee pain occasionally with associated kne e effusion. There is tenderness inferior to the patella, but extending beyond the margin of the patellar tendon. The pain is reproduced by straight leg raising. MR con \201 rms diag nosis and rules out other pathology. Management comprises rest and NSAIDs in the acute stag e. Taping of patella may help reduce amount of patella tilt and impingement. If conservativ e measures fail then arthroscopic resection of the fat pad can be helpful. \200 History Well localized pain at anatomical site. Other typical sites coincidentally affected (or previously given potential life- long predisposition to SpA disease) include heel, Ach illes \200\231 insertional, alternating buttock (?SIJ) and greater trochan- ter pains. A hi story of in \202 ammatory back pain should be sought. Patients may have psoriasis (or hist ory of it), Crohn \200\231s disease, or recent infection (with Chlamydia, Salmonella or Cam pylobacter, for example). 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