LOWER LEG AND FOOT 184 Lower leg and foot Regional anatomy The tibio \201 bular articulation The long bones of the lower leg articul ate at three distinct levels: \200 C The superior tibio \201 bular joint is a synovial joint, reinforced by the anterior and po sterior tibio \201 bular ligaments. The joint cavity may occasionally communicate posterio rly with the bursa deep to the popliteus tendon and the knee joint. The interosseous membra ne slopes steeply from tibia down to \201 bula. The inferior tibio \201 bular joint is a \201 brous joint (syndesmosis) reinforced by the interosseous, the anterior and the post erior tibio \201 bular ligament. T N Cu L I M The deep fascia of the leg The deep fascial envelope of the lower leg is fused to the perio steum of the subcutaneous parts of the tibia, the \201 b- ula and their malleoli. Two int ermuscular septa pass from its deep surface to become attached to \201 bula, forming comp artments in the leg. calcaneus talus navicular cuboid medial cuneiform intermediate cuneiform lateral cuneiform C T N Cu M I L = = = = = = = Any further increase in these tight spaces can cause compression and ischaemia of neurovasc ular and muscular structures (compartment syndrome). The peroneal (lateral) compartment This lies between the two intermuscular septa. It contai ns the p l a n t a r f l e x o r s a n d a b d u c t o r s of the foot and ankle \200\223 the peroneus longus and brevis muscles; and the super \201 cial peroneal nerve. Figure 5.41 Tarsal bones: dorsal view. The hindfoot retinaculae They are thickened bands of deep fascia at the ankle, which hold t he tendons (enclosed in synovial sheaths) of the muscles of the leg and neurovascular bundl es close to the joint as they pass into the foot. The anterior (extensor) compartment This lies between the anterior intermuscular septum and the tibia. It contains the dorsi \202 exors or extensors of the foot and ankle \200\223 tibialis anterior, extensor hallucis longus, extensor digitorum longus, and peroneus tertiu s muscles, the deep peroneal nerve, and the anterior tibial vessels. Functional compression of the nerves (entrapment syndrome) may occur if there is any increa se in the space between the retinacula and underlying bone. The posterior ( \202 exor) compartment This lies between the posterior intermuscular septu m and the tibia posteriorly. It contains the plantar \202 exors in two layers \200\223 t he gastrocnemius and soleus with plantaris muscles in the super \201 cial layer, which tog ether insert as the Achilles \200\231 tendon \200\223 the long \202 exors of the toes, \202 exor hal- lucis longus, \202 exor digitorum longus and tibialis posterior in the de ep layer. The neurovascular structures in this layer include the tibial nerve, the poplitea l vessels and its poste- rior branch, and the saphenous veins. The superior extensor retinaculum This extends between the triangular subcutaneous area of the \201 bula and the anterior border of the tibia. The inferior extensor retinaculum This is Y-shaped and attaches to the calcaneus laterally, and to the medial malleolus and medial side of foot. Structures passing beneath the extens or retinaculum include: \200 \200 \200 \200 \200 \200 Th e t e n d o n s o f t h e e xtensor digitorum longus. Extensor hallucis longus. Peroneus tertius. Tibialis anterior. The anterior tibial vessels. Deep peroneal nerve. Anatomy of the ankle and foot The ankle joint The ankle joint is a synovial hinge joint per mitting dorsi- \202 exion and plantar \202 exion. It is formed between the troch- lea t ali and the deep socket between the medial and lateral malleoli. The medial (deltoid) ligam ent and the lateral (an- terior and posterior talo \201 bular) ligaments contribute sig- n i \201 cantly to the stability of the joint. \200 Superior and inferior peroneal retinacula These pass, respectively, postero-inferior to the lateral malleolus and on the lateral surface of the calcaneus. The posterior talo \201 bular ligament attaches distally to the posterior tubercle of the talus. The talus ossi \201 es from a separate center and may be mistaken for a fracture; o r fail to fuse with the talus to persist as the os trigonum. Structures passing beneath the peroneal retinaculum: The common sheath of the peroneus long us and brevis tendons. The \202 exor retinaculum This stretches from calcaneum to the medial malleolus. CHAPTER 5 Regional musculoskeletal anatomy and conditions 185 Structures passing beneath the \202 exor retinaculum: the posterior tibial artery, and ne rve and the tendons of the tibialis posterior, the \202 exor digitorum longus and the \202 exor hallucis longus. Regional anatomy of the foot The arches of the foot The shape of the foot bones is of a hal f dome, concave inferiorly. The rim of the half dome consists of the heel, the lateral bord er of the foot, and the heads of the metatarsals. The skin covering these parts of the foot forms the foot- print. The medial non-weight bearing part of the foot forms two arches. The longitudinal arch This arch is \202 at on the lateral side. The talus lies at its sum mit. The calcaneus is the posterior pillar. The remaining tarsal bones and metatarsals form the longer anterior pillar. This arch is maintained by: \200 \200 \200 \200 The plantar calcaneonavicular ligament. All the plantar ligaments of the foot. The plantar aponeurosis. The insertions of the tibialis posterior muscle. FHL Ext Diminution of the normal longitudinal arch causes \200\230 \202 at foot \200\231 deformit y and an exaggerated arch produces \200\230club foot \200\231 deformity. T A The horizontal arch In the region of the tarsometatarsal bones this arch is maintained by t he plantar and interosseous ligaments and by the tendon of peroneus longus. Ta Ca Si Functional regions of the foot The foot can be divided into the following three sections: \200 The forefoot consists of the \201 ve metatarsals and is sepa- rated from the midfoo t by the tarsometatarsal joint. The midfoot contains three cuneiforms, the navicular, and t he cuboid, and is separated from the hindfoot by the transverse midtarsal joint. The hindfo ot consists of the calcaneus and the talus. N SP C M LP Mu Fat Figure 5.42 MRI of ankle, subtalar, and mid-tarsal joints (sagittal section). T, Tibia; Ta talus; Ca calcaneus; N, navicular; C, cuboid; M, metatarsal; Ext, extensor tendon; FHL, \202 exor hallucis longus; A Achilles tendon; Si, tarsal sinus containing interosseous liga ment; SP, short plantar ligament; LP, long plantar ligament; Mu, muscle of sole; Fat, locul ated subcutaneous fat in sole. tibialis anterior tibialis posterior extensor retinacula flexor dig. long. flexor hall. long. flexor retinaculum extensor hallucis longus Figure 5.43 Tendons, synovial sheaths, and retinacula on the medial side of the ankle and f oot. LOWER LEG AND FOOT 186 peroneus brevis and longus extensor digitorum longus extensor retinacula peroneal retinacula Figure 5.44 Tendons, synovial sheaths, and retinacula on the lateral side of the ankle and foot. (a) tendon of tibialis posterior tendon of peroneus longus plantar interossei medial aspect of 3rd - 5th metatarsals bases of proximal phalanges tendon of tibialis anterior plantar aponeurosis medial part central part lateral part axis of foot (b) medial process of calcaneus lateral process of calcaneus dorsal interossei adjacent sides of shafts of metatarsals bases of proximal phalanges Figure 5.45 Plantar aponeurosis. axis of foot Figure 5.46 Sole of foot muscle layer 4: plantar interossei. CHAPTER 5 Regional musculoskeletal anatomy and conditions 187 Fasciae The plantar aponeurosis, (or plantar fascia) runs from the plantar aspect of the ca lcaneus to the region of the meta- tarsal heads. (See Figure 5.4). \200 \200 Joints The subtalar joint The articulation of the calcaneus and talus, the joint is surroun ded by its own distinct capsule and does not articulate with other joints. \200 The super \201 cial layer blends with subcutaneous tissue. The deep layer joins the deep t ransverse metatarsal ligament and the \202 exor tendons. Normal range of motion is 5 of inversion and 5 of eversion. The subtalar joint provides inversion and eversion of the heel for walking on uneven terrain. Bursae \200 The retrocalcaneal bursa lies between the calcaneus and the Achilles tendon. This bursa has a synovial lining, which abuts the Achilles fat pad. Between the skin and the Achilles ten don is the subcutaneous calcaneal bursa. At the plantar aspect of the midcalcaneus is the s ubcalcaneal bursa. The transverse midtarsal joint of Chopart Composed of the talonavicular and calcaneocuboid joint the joint permits multi-axial motion, inversion and eversion of the midfoot and foref oot, and to a lesser degree, dorsi- \202 exion and plantar \202 exion, and abduction an d adduction. The bifurcate ligament stabilizes it. The tarsometatarsal joint of Lisfranc This joint comprises the interconnected second to \201 fth tarsometatarsal joints. A complex set of ligaments on their dorsal and plantar asp ects provide stability. Os trigonum The os trigonum may be seen in 3 \200\22315 % of feet. It may cause symptoms of pain and tenderness due to impinge- ment in plantar \202 exion in footballers or ballet dancers. \200 The os trigonum can be demonstrated on a plain lateral radiograph of the foot. It is import ant to differentiate this from an old non-united fracture of the normal posterior process s een in 38% of feet. The normal ossicle is smooth, well corticated, and has a normally lucen t central medulla. Chronic impingement causes central sclerosis and cortical irregularity, with pitting and local soft-tissue oedema. MR may show changes of osteonecrosis and soft ti ssue swelling. The metatarsophalangeal joints The deep transverse metatarsal ligament and the plantar liga ments stabilize these joints. The \201 rst metatarsophalangeal joint The joint plays a critical role in normal gait. Un der most conditions, 65 \200\22375 of dorsi \202 exion of the hallux on the \201 rst m etatarsal is required for normal gait and for the hallux to function in propulsion. Disorders such as hallux valgus and hallux rigidus affect gait adversely by limiting dorsi \202 exion of the \201 rst metatar- sophalangeal joint. Further reading Balint GP, Korda J, Hangody L, et al. Foot and ankle disorders. Best The interphalangeal joints The toe joints are hinge joints stabilized by collateral ligamen ts and a plantar capsular ligament with a \201 brous plate. Pract Res Clin Rheumatol 2003; 17: 87 \200\223111. Romanes GJ. Cunningham manual of practical anatomy 1996, 15th edn. Weakness of the lumbricals, which extend the interpha- langeal joints, produces \200\230ha mmer toe \200\231 deformity (extended metatarsal joints and flexed proximal interphalangeal joints). Sinnatamby CS. Last \200\231s regional and applied anatomy, 10th edn, p. 112. LOWER LEG AND FOOT: REGIONAL MUSCULOSKELETAL CONDITIONS 188 Lower leg and foot: regional musculoskeletal conditions Pain can be due to local lesions or referred from the lum- bar spine lesions, though the la tter is usually posterior and/ or lateral in the lower leg. History Stress fractures are common in dancers, runners, and jumpers, and occur in older pe ople with osteoporosis. Women athletes with amenorrhoea are particularly at risk of bone fr agility. The pain often worsens with exercise. Differential diagnosis of lower leg pain \200 \200 \200 \200 \200 \200 \200 Examination and investigations There is local tenderness and swelling. Initially, radiograp hs are normal, but 99mTc MDP scintigraphy or CT scanning can be diagnostic. CT is often nec essary to differentiate from tumors. Compartment syndromes. Ruptured popliteal cyst. Deep venous thrombosis. Stress fractures. F ibular tunnel syndrome. Tibialis anterior tenovaginitis. Radicular pain (lumbar disc prolap se, lateral recess stenosis or central lumbar canal stenosis; see p. 132). Periostitis. Ost eitis/bone marrow pain (e.g. Paget \200\231s; see p. 418). Peripheral neuropathy. Erythrome lalgia (hot feet/legs, burning pain, erythema; see: www.erythromelalgia.org). Myositis (cal f muscles). Panniculitis (see p. 514). Management Early recognition is important. Rest is necessary for up to 6 weeks. Exercise in water helps maintain \201 tness in elite athletes and others. Addressing amenorrhoea is important in premenopausal athletes and osteoporosis investigation prudent in both men and women. \200 \200 \200 Ruptured popliteal cyst Acute pain, swelling and skin erythema of the lower leg suggests th is. Differential diagnoses: cellulitis and DVT. \200 \200 Pedal ecchymosis may discriminate the diagnosis from cellulitis or DVT. A history of preced ing knee or popliteal swelling is often present. The swelling then often subsides commensur ate with the evolution of lower leg swelling. Popliteal cysts form as part of in \202 amma tory knee arthritis or secondary to trauma, which induces either an intra- articular knee s welling or \202 uid accumulating from an extended selling of the semimembranosus bursa. U ltrasound to rule out femoral DVT is sensible. Adequate analgesia including an NSAID, patie nt reassur- ance, limb elevation, and icing is appropriate. Some monitoring of the leg and foot is important \200\223 compartment syndrome is a recognized complication. Although it is not known how effectively glucocorticoid (GC) injected into the knee reduces lower leg s welling (presumably by accessing compartments through the breach in the cyst), an intra-art icular GC injection is often undertaken. Compartment syndromes Increased pressure in con \201 ned anatomic compartments of the leg causes compartment syndrome, leading to isch- aemia of the muscles and nerves. Unrelieved, pressure causes muscle necrosis and permanent nerve damage. In the lower leg, the anterior compartment syndrome is most commonly affected. \200 \200 Acute compartment syndrome is a surgical emergency, and can follow trauma or prolonged surg ery in the lithotomy or hemi-lithotomy position, or can complicate deep tissue infection or rhabdomyolysis. Acute lower leg extremity compartment syndrome (ALECS) commonly complicate s major trauma and appropriate patients should be carefully screened. Chronic exertional co mpartment syndrome occurs dur- ing or after exercise and causes diffuse cramp-like pain, wh ich resolves with rest, but recurs with exertion: \200 Fibular tunnel syndrome This is an entrapment neuropathy lesion of the peroneal nerve. The common peroneal nerve (CPN) lies on the neck of the \201 bula, which forms the \202 oor of the \200\230 \201 bular tunnel \200\231. The tunnel entrance is a musculo-aponeurotic arch derived from soleus and peroneus longus muscles. The CPN is commonly compressed in th is tunnel in cases of CPN palsy. In some, however, the nerve follows a more tortuous course higher up where the distal rectus femoris passes adjacent to the lateral head of the gastr ocnemius and this has been proposed as a factor increasing the risk of CPN symptoms. \200 blood \202 ow scintigraphy suggests ischaemia alone does not account for all cases; cause s can be varied and investigations that may be necessary include 99mTc-MDP and exercise-rel ated blood \202 ow (201Tl-SPECT) scintigraphy and MR or conventional angiography; the dia gnosis is easily overlooked and can be con- \201 rmed by intra-compartmental pressure mon itoring before and during exercise. It resolves with rest Pre- and post-operative intracompartmental pressure monitoring con \201 rms ef \201 cacy of either open or endo- scopic surgical decompression. Post-traumatic CPN entrapment usually occurs after fracture, compression by a walking cast, or sitting cross-legged. The patient complains of parasthesias or numbness of the lateral calf and foot. Rarely, a foot drop develops. The lesion can be localized by nerve conductio n studies. Causative factors should be addressed. Partial weakness of peroneus longus and b revis is possi- ble and a risk factor for falls. Stress fracture of tibia Stress fractures occur as the result of fatigue failure from repet itive loading below yield strength and are most com- mon in the lower leg. Often there is a focal structural and/ or muscle weakness. \200 \200 Differential diagnoses are osteoid osteoma, chronic sclerosing osteomyelitis, osteomalacia, periostitis, metasta- ses, osteogenic sarcoma, Ewing \200\231s tumor. CHAPTER 5 Regional musculoskeletal anatomy and conditions 189 Periostitis A cause of persistent, immobility-related pain of the front or medial aspect of the leg. Pain is often reported with a burning quality and can disturb sleep. \200 \200 Can mimic pain from tibial stress fractures. Terminology can often confuse. Shin splints is regarded as an outdated term for periostitis of the upper medial tibia now termed medial t ibial stress syndrome. 99mTc-MDP scintigraphy can highlight lesions and show lesions elsewh ere (e.g. SIJs, periostitis in other leg, PsA/ SAPHO). Neurophysiology tests may characteri ze nerve lesions in cases where imaging is negative or show that dual pathol- ogy exists (e .g. sarcoid, PAN). However, tests are often negative in small \201 bre sensory neuropathy in the elderly. Treat underlying cause. Consider NSAIDs or IV bisphosphonates for periosti tis or osteitis, respectively. \200 Further reading Anselmi SJ. Common peroneal nerve compression. J Am Podiatr Med Assoc 2006; 96(5): 413 \200\22317. Figure 5.47 Popliteal cysts can be large and \202 uid can accumulate causing high-pressur e lesions. Fluid leakage into the calf is a common consequence of large popliteal cyst form ation. Aoki Y, Yasuda K, Tohyama H, Ito H, Minami A. Magnetic resonance imaging in stress fracture s and shin splints. Clin Orthopaed Relat Res 2004; 421: 260 \200\2237. Fayad LM, Kamel IR, Kawamoto S, Bluemke DA, Frassica FJ, Fishman EK. Distinguishing stress fractures from pathological fractures: a multimodality approach. Skeletal Radiol 2005; 34(5 ): 245 \200\22359. Fottner A, Bauer-Melnyk A, Birkenmeier C, Jansson V, D rr HR. Stress fr actures presenting as tumors: a retrospective analysis of 22 cases. Int Orthopaed 2007; Dec 14. Epub ahead of print. Podiatric, orthotist and/or occupational therapy review is an important part of conservativ e management so that appropriate foot support is maintained (e.g. splinting). Surgical expl oration and release of the nerve may be necessary. Howard JL, Mohtadi NG, Wiley JP. Evaluation of outcomes in patients following surgical trea tment of chronic exertional compartment syndrome in the leg. Clin J Sports Med 2000; 10(3): 176 \200\22384. Recognized causes of tibial periostitis \200 \200 \200 \200 \200 Kosir R, Moore FA, Selby JH et al. Acute lower extremity compart- ment syndrome in critical ly ill trauma patients. J Trauma 2007; 63: 268 \200\22375. Posteromedial tibial periostitis ( \200\230shin splints \200\231). Sarcoid (see p. 510). Ps oriatic arthropathy (PsA; see p. 220). Polyarteritis nodosa (PAN; see p. 332). Primary hype rtrophic osteoarthropathy (pachyder- moperiostitis). Secondar y hyper trophic osteoar throp athy (e.g. malignancy, HIV disease). Associated with Crohn \200\231s disease. SAPHO syndrom e (see p. 236). Syphilis. Meyer RS, White KK, Smith JM, Groppo ER, Mubarak SJ, Hargens AR. Intramuscular and blood pr essures in legs positioned in the hemilithotomy position: clari \201 cation of risk factor s for well-leg acute compartment syndrome. J Bone Jt Surg Am 2002; 84-A: 1829 \200\22335. Ryan W, Malone N, Delaney M, O \200\231Brien M, Murray P. Relationship of the common perone al nerve and its branches to the head and neck of the \201 bula. Clin Anat 2003; 16: 501 \200\2235. \200 \200 Viera RL, Rosenberg ZS, Kiprovski K. MRI of the distal biceps femoris muscle: normal anatom y, variants, and association with common peroneal entrapment neuropathy. Am J Roetgenol 200 7; 189: 549 \200\22355. CONDITIONS OF THE ANKLE AND HINDFOOT 190 Conditions of the ankle and hindfoot Discrete musculoskeletal lesions of the foot are often to diagnose precisely. Functional ex amination is not always speci \201 c and imaging tends to be less speci \201 c in identif ying pathology compared with more proximal sites. The foot is a common site for in \202 am matory arthritides to affect. A knowledge of typical patterns of involvement of structures associated with the Spondylarthropathy conditions (see pp 209 \200\223238) \200\223 especi ally psoriatic arthritis \200\223 and sarcoid is useful for the rheumatologist. These cond itions can affect entheses and periosteum as well as synovial joints and ten- dons. Involve ment of the ankle or subtalar joint is relatively common in CPPDD disease regardless of whe ther pseudo- gout manifestations are, or have been, present. Gout can affect, in theory, an y joint or tendon in the foot but gout frequently causes non-articular tissue in \202 amma tion in soft- tissues and if this is diffuse it can be mistaken for cellulitis for example. joint hypermobility syndrome and other disorders associ- ated with joint hypermobility. Suc h patients are at increased risk of recurrent inversion/pronation ankle strains. Imaging Look for osteophytes/enthesophytes of the distal tibia and the talar neck on obliqu e plain radiographs. If ankle effu- sion is present, MR may demonstrate a \200\230meniscoi d \200\231 mass within the lateral gutter of the ankle. Talar enthesophytes can be a part o f PsA and DISH, as well as due to simple degenerative changes. Anteromedial impingement syndrome History Presents as anteromedial ankle pain. Ask about pr evious inversion injury or fracture of the ankle or talus. Examination Anteromedial swelling and tenderness may be present. Look for painful restricte d dorsi \202 exion and supination of the ankle. Table 5.11 Region of foot Discrete musculoskeletal lesions Imaging Anteromedial talus osteophytes/enthesophytes may be seen on plain radiography. MR a rthrography shows: abnormal appearance of the anteromedial capsule, irregular synovial fold ing anterior to the tibiotalar ligament and medial malleolus, and presence of tibial osteop hytes. Hindfoot (general) Ankle or subtalar arthritis Osteochondral fracture of talus Periostitis (distal lower leg) Peroneal tendonitis (lateral) Medial ankle Medial ankle impingement syndrome Tibialis posterior tendonitis/dysfunction Tarsal tunnel s yndrome Anterolateral ankle impingement syndrome History Presents as anterolateral ankle pain. Ask about previous inversion injury to the ankle. Lateral ankle Peroneus longus and brevis tendonitis Lateral pre-malleolar bursitis Examination Feel for tenderness in the area of antero-inferior tibio \201 bular ligament a nd/or anterior talo \201 bular ligament. Anterior ankle Anterior ankle impingement syndromes Dorsal (extensor) tendonitis Tibialis anterior tendonitis Imaging Plain radiographs may occasionally show small osteophytes on the anterior tibial ma rgin. Increased anterior translation of the talar dome can be seen on stress radiographs in approximately half the cases. Posterior ankle Posterior ankle impingement syndrome Achilles \200\231 tendonitis/enthesitis/bursitis Heel Plantar fasciitis Calcaneal stress fracture Tarsal tunnel syndrome (plantar + sole) Posterior ankle impingement syndrome. History Common in ballet dancers from weight-bearing in maximal plantar \202 exion, especially when os trigonum is present. Midfoot Arthritis or enthesitis Sinus tarsi syndrome (lateral pain) Peroneus tendonitis/enthesitis (lateral) Accessory navicular (medial) Osteonecrosis of navicular Examination Tenderness may be elicited behind the lateral malleolus. Passive plantar- \202 exion is often painful. Toes Arthritis of MTPJs Inter-metatarsal bursitis Morton \200\231s neuroma Metatarsal stress fra cture Hallux lesions: valgus, rigidus Dactylitis Imaging Plain radiographs may detect os trigonum or trigonal pro- cess. MR imaging can demo nstrate hypertrophy or tear of the posteroinferior tibio \201 bular (PITF) ligament, trans verse posterior tibio \201 bular ligament, or the \200\230tibial slip \200\231 running be tween the PITF ligament and the transverse ligament. Ankle impingement syndromes Anterior ankle impingement syndrome History Ongoing anterior an kle pain may be present. Enquire for a supination injury or repeated dorsi \202 exion inju ry. Management of impingement syndromes Conservative management Rest, NSAIDs, proper footwear, ankle support aids and physiotherapy is the \201 rst line of treatment. Failing this intr a-articular glucocorticoid injections (2 or 3 times in 10 \200\22314-day intervals) to redu ce synovial in \202 ammation. Examination Dorsi \202 exion of the ankle is painful and restricted. General- ized connect ive tissue laxity may be present \200\223 consider CHAPTER 5 Regional musculoskeletal anatomy and conditions 191 Operative management In failed conservative management arthroscopy with debridement and rem oval of the hypertrophic synovial tissue, and the osteophytes often provides good results. hindfoot to invert. Weakness may be noted on resisted active inversion of the fully plantar \202 exed foot. Ask for weight-bearing bilateral anteroposterior and lat- eral plain rad iographs for subtle unilateral pathology. US or MR will characterize tendon pathology. Loca l glucocorticoid injection may be appropriate in cases of in \202 ammatory tendonitis, alt hough where there are advanced changes or dysfunction without in \202 amma- tion, it is be st avoided. Orthoses and exercise may be useful in the early non- acute phases though there are no robust RCTs of such methods. Tenosynovectomy and debridement is needed in acute pre sentations. Arthrodesis and tendon transfers may be necessary for failed conservative treat ment. \200 Lateral pre-malleolar bursitis There is often history of the foot being in prolonged period s of plantar-flexed and inverted position (e.g. Muslims during prayer). Ultrasound is often helpful to rule out other soft tissue swelling. \200 \200 \200 \200 \200 Differentiate from pre-malleolar fat pad and a ganglion. Advise not sitting on the foot. NS AIDs and physiotherapy may be bene \201 cial. Avoid intra-bursal steroid injections. Excis ed bursa where conservative management fails. Tarsal tunnel syndrome Tarsal tunnel syndrome is often under-diagnosed as a cause of foot p ain. The posterior tibial nerve and the \202 exor hallucis and digitorum longus tendons p ass behind the medial malleolus under the \202 exor retinaculum. \200 Peroneal tendonitis Both peroneal tendons may be affected. Peroneus longus tendonitis prese nts as lateral hindfoot pain and cavovalgus foot deformity. The peroneus longus tendon is s usceptible to damage at three places: \200 \200 \200 Entrapment of the nerve in this \200\230tunnel \200\231 can occur due to bony deformity af ter an ankle fracture, a \202 at foot, in \202 am- mation of the tendons, or compression from an ankle synovial cyst. Patients present with burning, tingling, and numbness in the distribution of the nerve, notably the toes and distal part of the sole and heel. This is o ften worse at night. An aching calf at night may also be present. Tenderness and swelling m ay be present around the medial malleolus. A positive Tinnel \200\231s sign elicited by per - cussion of the \202 exor retinaculum con \201 rms the diagnosis. Reduced vibratory sen sation and decreased two-point discrimination may be present on the plantar aspect of the f oot and toes. In doubtful cases, nerve conduction studies may be used to document delay in conduction of the posterior tibial nerve across the ankle. Denervation on needle sampling i s also reliable. MR may be useful in the evaluation of anatomical structures. For conservat ive management use NSAIDs and gluco- corticoid injection under the retinaculum between the calcaneum and medial malleolus. Orthotics can reduce abnormal movement of the foot in the g ait cycle. Treatment of any local cause for compression is appro- priate. Occasionally, sur gical section of the retinaculum is necessary. In resistant cases, surgical decompression o f the posterior tibial nerve may be necessary. At the calcanear trochlear process. At the inferior peroneal retinaculum. At the cuboid not ch, where the tendon sharply changes its direction passing the plantar surface of the foot. The management should be primarily conservative, but tendon rupture needs surgical treatmen t. Sinus tarsi syndrome In the tarsal sinus lies an arterial anastomosis, three roots of the i nferior extensor retinaculum, the cervical ligament, the tarsal canal ligament, and fatty t issue. There is some controversy as to the precise cause and nature of the condition. \200 There may be a history of inversion injury or in \202 amma- tory joint disease. The syndro me consists of lateral foot pain (relieved by injection of local anesthetics), foot instabi lity (e.g. previ- ous injury or intrinsic hypermobility) and tenderness of the sinus tarsi. MRI shows obliteration of fat in the sinus tarsi space. Locally administer steroid injecti on. Chronic cases may warrant synovectomy and reconstruction of the collat- eral ligament. \200 Osteochondral lesion of the talus (OLT) There are a number of synonyms: osteochondral defec t, osteochondral fracture, osteochondritis dissecans. There is separation of a fragment of articular cartilage with or with- out subchondral bone of the talar dome. \200 Posterior tibial tendon dysfunction The posterior tibial tendon suspends the medial arch of the foot. Dysfunction and rupture of the tendon results in acquired unilateral flatfoot, v algus hindfoot, forefoot abduction, and talonavicular subluxation. \200 Plain radiographs may demonstrate the fragment and ligament injury is usually detectable in these cases. MR can be used to differentiate avascular necrosis when plain radiographs are negative. Non-operative treatment is successful in 45% cases. Excision, curettage and dril ling are successful in 85%, excision and curettage in 78%, and excision alone in 3%. Mosaic plasty (osteochondral graft transplant) and autol- ogous chondrocyte transplantation are pr omising meth- ods for the future. Not uncommon in middle-aged obese women. Associated medial or lateral ankle pain may be pre sent. Pes planovalgus results in \200\230too many toes sign \200\231 when the foot is insp ected from behind. (More of the lesser toes visible lateral to ankle joint than on the unin volved side.) On palpation, the tendon sheath may be tender and swollen. Speci \201 cally look for dif \201 culty in performing a single-limb heel rise. At heel rise there may be p ain under the medial malleolus and inability of the valgus CONDITIONS OF THE ANKLE AND HINDFOOT 192 Achilles tendonopathy Achilles tendonopathy, enthesopathy, and retrocalcaneal bursitis are characteristic features of SpA. Heel pain is often the \201 rst manifestation of the dise ase. Retrocalcaneal/subcutaneous calcaneal bursitis Also known as \200\230pump bumps \200\231, it is rarely a complication of in \202 ammatory joint disease, but is usually caused by ir rita- tion of stiff heel counters. \200 \200 The overlying skin is usually reddish or hyperkeratotic. The management consists of wearing counterless shoes, padding and NSAIDs. Local glucocorticoid injections should be avoided b ecause of the risk of infection. Causes of Achilles \200\231 tendononpathy \200 \200 \200 \200 Spondylarthropathy. Acute or chronic trauma. Fluoroquinolone-induced. Associated conditions : \200 \200 \200 Injudicious use of glucocorticoid injection Plantar fasciitis (PF) Plantar fasciitis is an enthesopathy of the calcaneal tuberosity. Th ere are both mechanical and autoimmune in \202 ammatory aetiologies. Pure mechanically-ind uced PF is caused by over-use, repetitive strain, or microtrauma. PF is a common in lesion in spondylarthropathy conditions and chronic musculoskeletal sarcoidosis. \200 haemodialysis; hypercholesterolaemia (xanthomas); diabetes. There is pain and/or stiffness on the plantar heel surface occasionally extending along the proximal sole. Symptoms are often worse with the \201 rst few steps of the day. Ask abou t current or previous in \202 ammatory back pain (see p. 210), psoriasis, and pain at enth eses elsewhere. Tenderness is maximal over the medial calcaneal tubercle. A positive heel s queeze test can discriminate pain from os calcis stress fractures (os calcis squeezed betwe en the heels of your hands from both sides). Lateral os calcis radiograph and, if necessary , CT, can help rule out calcaneal stress fracture. Characteristic MR, 99mTc-MDP scintigraph y and US appearances have been described. In traumatically-induced lesions, 25% of injuries may be missed at the \201 rst presentat ion. The pathological changes described in the tendon may be broadly characterized as tendo nosis without in \202 ammation and in \202 ammation of the paratenon (surrounding tendon sheath). In cases of rupture, the site is usually in a relatively hypovascular region of th e tendon 2 \200\2236 cm proximally from the insertion. Rupture may also occur at the enthe- sis or at the muscle/tendon junction. The rupture is unusually painful in \202 uoroquino lone- induced tendonopathy. Otherwise, especially in chronically developing ruptures, the p ain is not severe or is totally absent. SpA-related lesions (enthesopathies) are characteri zed by tenderness over the posterior os calcis, irregularly de \201 ned erosions and/or de position of bone with de \201 ned excrescences in the healing stage. Examine with patient standing from behind and compare sides. Examine then with patient prone and feet over end o f couch. Pathology at muscle-tendon junction, Achilles tendon (cord) and insertion can be p alpated. Squeezing the calf plantar- \202 exes foot if tendon intact. US may predict the o utcome of achillodynia. Differentiation of full- and partial-thickness tears can be made wi th 92% accuracy using US and characteristic appearances at the enthesis has been described in SpA- related disease. MR imaging frequently shows intra-tendonous changes during \202 uoroquinolone treatment even in the absence of any clinical signs. 99mTc-MDP scintigraphy h ighlights enthesopathy at the site and other places in SpA. Management of PF Conservative management: rest, night splints, use of soft rubber heel pads , foot orthoses to support of the longitu- dinal arch, and physiotherapy may all have a rol e. \200 NSAIDs and local GC injection can be considered. Evidence for long-term ef \201 cacy of th e latter however is lacking. US-guided GC injection is no more effective than palpation-gui ded injection. Surgical release of the plantar fascia is rarely required. Healing problems of the overlying skin are relatively frequent. Endoscopic plantar fasciectomy is a recently - developed technique, which probably causes fewer com- plications compared with open surge ry. External beam radiotherapy can be helpful in recalcitrant cases. A number of alternativ e treatment modalities have been reported. The ef \201 cacy of lithotripsy, botulinum inje ction, autologous blood injection has not been proven in long- term robust studies compared with GC injection. Management of Achilles \200\231 tendonopathy Non-in \202 ammatory lesions Protection of th e foot and heel support is appropriate. Surgery is required in the case of complete rupture and provides good results but a rather high (15%) percentage of complications. Further reading Irving DB, Cook JL, Menz JB. Factors associated with chronic plantar heel p ain: a systematic review. J Sci Med Sport 2006; 9(1 \200\2232): 11 \200\22322. Paige NM, No uvong A. The top 10 things foot and ankle specialists wish every primary care physician kne w. Mayo Clin Proc 2006; 81: 818 \200\22322. Wearing SC, Smeathers JE, Urry SR, Henrig EM, Hills AP. The patho- mechanics of plantar fas ciits. Sports Med 2006; 36(7): 585 \200\223611. In \202 ammatory SpA-related lesions NSAIDs and orthotics for heel support. Physiotherapy in recovering cases to avoid shortening of posterior heel structures. Glucocorticoid inject ions over the enthesis can be considered in isolated enthesitis or where paratenon inflamma tion exists without intra-tendon substance changes (demonstrable on US). This page intentionally left blank CONDITIONS OF THE MID AND FOREFOOT 194 Conditions of the mid and forefoot Accessory navicular bone This is present in 4 \200\22321% of the population and can be a ca use of medial midfoot pain. An accessory navicular is a large triangle or heart-shaped ossi cle attached with a cartilaginous or \201 brocartilaginous synchondrosis to the navicular bone. It is thought to be a source of symptoms owing to a chronic stress reaction. \200 For differential diagnosis between Morton \200\231s neuroma and MTPJ arthritis, local anest hetics can be given either into the interspaces proximally to the metatarsal head or into t he corresponding MTPJ. This \200\230ex juventibus \200\231 effect may show what is the pro bable cause of pain. US or MR can also be used for differential diagnosis. Surgical excisio n of the neuroma may be undertaken in symptomatic cases. \200 The bone con \201 guration and its involvement in \200\230bony stress \200\231 can be dem onstrated on radiographs or CT and bone scintigraphy, respectively. An accessory navicular bone may also damage the posterior tibial tendon. The management consists of resting from s ports activities or surgical excision of the accessory bone. Stress fractures of the metatarsals These fractures are common in runners, ballet dancers a nd other sports where there is inadequate shoe support, but they are also found in the midd le-aged or the elderly doing sporting activities. Stress fracture also occurs in diabetic o steoarthropathy, and can indicate generalized or regional osteoporosis. Regional cortical-r ich bone osteoporosis is a feature of hyperparathyroidism. The Mueller \200\223Weiss syndrome Osteochondritis/necrosis of the navicular bone. This occ urs more frequently bilaterally in adult women. The management is conservative with rest an d orthotic foot support as necessary. A failure of conservative therapy can lead to permane nt degenerative midfoot arthritis. Radiologically occult fractures can be detected by MR imaging or bone scintigraphy if clini cal suspicion remains when radiographs are normal. With MR and/or bone scin- tigraphy even the pre-fracture state of stress injury can be diagnosed. Plantar plate disruption A common cause of metatarsalgia. It occurs frequently in women wea ring high-heeled shoes. The second MTPJ is most commonly affected. Diagnosis can be made by MR. Freiberg \200\231s infarction Probably an osteonecrosis of the second or third metatarsal h ead, causing secondary osteoarthritis of the adjacent MTPJ. High-heeled shoes, repetitive i njury or trauma may be causative factors. Intermetatarsal bursitis Overstrain of the MTPJ region often results in bursitis of the int ermetatarsal bursae or adventitial bursae beneath the metatarsal heads. Bursitis can also b e caused by repetitive trauma, infection, RA, SpA, or gout.