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Common disorders of the adult foot and ankle
ORTHOPAEDIC SURGERY
Common disorders of the adult foot and ankle Patrick Laing
The foot is a complex structure composed of 26 main bones. It must be supple to absorb shock on landing, support the body in stance phase and turn itself into a rigid lever for propulsion. Modern foot and ankle surgery ranges from arthroscopy to joint reconstruction and replacement. This contribution should be read in conjunction with ‘Degenerative and rheumatoid arthritis (including joint replacement)’, page 32. 1 MRI scan of an osteochondral lesion of talus (arrow).
Sports injuries Ankle sprains are very common and most patients will settle down with simple conservative treatment (ice, compression, elevation). However, about 25% of sprained ankles progress to chronic residual symptoms. This may be because of lateral ligament instability, but may be due to injury to other structures in and around the ankle, e.g. osteochondral lesions of the talus (see below), subluxing peroneal tendons, other injuries to the peroneal or tibialis posterior tendons.
continue to cause symptoms and these can be treated with autologous chondrocyte implantation. A sample of articular cartilage is taken from the knee and grown in the laboratory before being reimplanted into the ankle. This is a new and exciting development which potentially offers the chance to rebuild normal articular cartilage rather than fibrocartilage. Other conditions: loose bodies, osteochondritis dissecans and cheilectomy of anterior tibial spurs (common in footballers) are other conditions which can be dealt with arthroscopically.
The anterior talofibular ligament is the first ligament to tear in inversion injuries. The torn anterior talofibular ligament may lead to scar tissue in the lateral gutter of the ankle, which gives rise to local tenderness and pain on activity. This can be treated arthroscopically. In more severe injuries, the calcaneofibular ligament is also torn and may also tear independently of the anterior talofibular ligament.
Arthritis of the hind and midfoot Primary osteoarthritis of the ankle joint Primary osteoarthritis of the ankle joint is relatively rare and it is more common for arthritis to follow trauma (e.g. ankle or pilon fractures) or to occur secondary to an inflammatory arthropathy (e.g. rheumatoid arthritis). Patients present with a stiff and painful hindfoot and may walk with the foot externally rotated, which allows them to roll off the medial border of the foot. Their walking distance will be limited and they may get pain at night and pain on rising to walk after resting. In addition, they may have deformity with either varus or valgus at the hindfoot.
Torn lateral ligaments are treated conservatively, first with peroneal strengthening and wobble-board exercises. If instability persists, then either a direct repair of the anterior talofibular and calcaneofibular ligaments of the ankle (Brostrum–Gould repair) may be performed or part of peroneus brevis used to substitute for the lateral ligaments. Osteochondral lesions of the talus are localized defects of the articular cartilage and underlying bone which may cause ongoing pain (Figure 1). They are usually treated with arthroscopic debridement and the lesions fill in with fibrocartilage. Larger lesions may
Treatment: conservative treatment may consist of: • physiotherapy • corticosteroid injections • orthotic support. Arthroscopic debridement has a limited role surgically and the main operative treatment is either an arthrodesis or arthroplasty. Following an ankle arthrodesis, patients generally walk with a good gait. However, non-union rates of 10–15% are not uncommon. Arthrodesis may also be performed arthroscopically if deformity is minimal and may offer a better and quicker rate of union. The
Patrick Laing is a Consultant Orthopaedic Surgeon at Wrexham Maelor Hospital, Wrexham, UK, and the Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, UK.
SURGERY
45
© 2004 The Medicine Publishing Company Ltd
ORTHOPAEDIC SURGERY
2 Radiograph showing total ankle replacement (note screws from fixation of previous lateral malleolar fracture).
3 Valgus hindfoot in patient with ruptured tibialis posterior tendon.
optimum position is neutral for dorsiflexion/plantarflexion and about 5° of valgus and external rotation. Arthrodesis of one joint will put strain on neighbouring joints and, if subtalar arthritis is present before ankle arthrodesis, it may progress. Ankle joint replacements usually consist of metal tibial and talar components with an interposition polyethylene spacer, and give prosthesis survival rates of 85% after 15 years (Figure 2).
lateral malleolus due to impingement. The forefoot is abducted and externally rotated. Hence, when observing the foot from behind, one sees more toes on the affected foot than on the normal foot (‘too many toes’ sign, Figure 3) and the heel does not invert when the patient is asked to stand on tiptoe. Treatment: in the early stages, tenosynovitis may be treated conservatively with: • physiotherapy • NSAIDs • cast immobilization • orthotic support. If unresponsive, surgical treatment with decompression of the tendon sheath and synovectomy may be necessary. If the tendon is ruptured, reconstruction is possible using part of tibialis anterior or the long flexors, often combined with a calcaneal osteotomy. The prerequisite for this is a mobile foot. In long-standing deformity, fixed supination of the forefoot develops and a triple arthrodesis is usually necessary to give a plantigrade foot.
Arthritis of the subtalar, talonavicular or calcaneocuboid joints Arthritis of the subtalar, talonavicular or calcaneocuboid joints may occur primarily, but usually follows trauma or inflammatory arthritis (e.g. rheumatoid). Subtalar arthritis may follow talar fractures or intra-articular fractures of the calcaneum. Patients often complain of ankle pain and commonly have pain whenwalking over rough ground. Patients with talonavicular arthritis usually locate the pain over the dorsum of the foot. Sometimes it may be difficult to ascertain which joint is causing the patient’s main symptoms and selective local anaesthetic injections, under radiographic guidance, may be helpful. However, communication between joints is not uncommon.
Cavus foot
Treatment: conservative treatment is similar to that given for arthritis of the ankle; arthrodesis is the surgical treatment. Arthrodesis of any one of these joints reduces movement in the others and an isolated subtalar arthrodesis gives the best functional results. When performing a subtalar fusion, the hindfoot should be placed in slight valgus to maintain mobility in the transverse tarsal joints. A fusion of the subtalar, talonavicular and calcaneocuboid joints is known as a triple arthrodesis; if the ankle joint is also arthrodesed, this is known as a pantalar fusion.
The opposite of a flatfoot is a cavus or high-arched foot. The cause is usually idiopathic, but can occur because of: • neuromuscular disorders, e.g. hereditary sensory and motor neuropathy or spinal dysraphism • residual clubfoot deformity (see CROSS REFERENCES) • trauma. Muscular imbalance may lead to a plantarflexed 1st ray, which causes a varus heel and a pes cavo-varus deformity. Patients with a varus heel are prone to recurrent lateral ligament sprains and occasionally this may be the mode of presentation. In association with the high arch, there is often marked clawing of the toes and patients complain of difficulty finding comfortable footwear. Initial investigation should establish the cause of cavus foot.
Adult-acquired flatfoot deformity The tibialis posterior tendon is second only to the Achilles tendon in strength, yet has a short excursion (2 cm). The tibialis posterior tendon inverts and plantarflexes the foot. Dysfunction and attrition ruptures may occur, predominantly in middle-aged females, leading to a progressive flatfoot deformity with valgus of the hindfoot. Initially, patients get medial pain along the tendon and, following tendon rupture, may then develop pain under the tip of the
SURGERY
Treatment: most patients are treated orthotically. Surgical treatment varies according to individual cases, and ranges from toe straightening to tendon transfers, osteotomies and fusions. 46
© 2004 The Medicine Publishing Company Ltd
ORTHOPAEDIC SURGERY
• ultrasound-guided corticosteroid injections. Surgery may have a role, but results vary greatly; a number of reports have shown that extra-corporeal shock wave therapy can be very effective in plantar fasciitis.
Hallux valgus Hallux valgus, a lateral deviation of the hallux, is a common deformity in shod populations, but far less common in those who do not wear shoes. There is a strong family history in over 50% of patients, although the cause is multifactorial. The bunion is the prominent medial eminence of the 1st metatarsal and patients experience pain, particularly when wearing tight shoes. The ‘mirror image’ of a bunion is sometimes seen at the 5th metatarsal, when it is known as a bunionette (tailor’s bunion). This can be very uncomfortable, especially in association with a bunion.
4 Neuropathic diabetic foot ulcer.
Treatment: conservative treatment is shoewear modification to accommodate the deformities. Operative treatment will depend on the degree of deformity and the angle of the joint. Smaller deformities may be treated with a distal metatarsal osteotomy (e.g. Chevron). Larger deformities require release of the tight lateral soft tissues, along with a proximal 1st metatarsal osteotomy. No single operation is suitable for all types of deformity. In recent years, the Scarfe osteotomy has gained popularity in the UK due to its versatility (Figure 5).
Diabetic feet Diabetic feet are liable to ulceration because of the diabetic complications of neuropathy and peripheral vascular disease. Peripheral and autonomic neuropathy lead to a dry, insensitive cavus foot with clawed toes. Patients develop high pressures under the metatarsal heads on walking. The neuropathic foot is often well perfused and ulceration occurs because of the high pressures and unperceived injury (Figure 4). Ulcerated infection may supervene, leading to cellulitis and deep infection with osteomyelitis. The patient is then at risk of amputation.
Hallux rigidus Simple hallux valgus usually causes pain only in patients wearing shoes. Patients who complain of pain walking barefoot, as well as in shoes, and aching at night should be suspected of arthritis in the 1st metatarsophalangeal joint. On examination, there is pain on compression and rotation of the joint and there may be limited movement, i.e. hallux rigidus. The initial movement lost is usually dorsiflexion.
Treatment: simple ulcers may be treated by reducing the pressures in a total contact cast and, once healed, maintaining low pressures with appropriate insoles and footwear. Surgery may be necessary to treat acute infection or recurrent ulceration when fixed deformity is present.
Heel pain
Treatment: a painful hallux rigidus can be treated conservatively by stiffening the shoe shank and adding a rocker; injection of corticosteroid and local anaesthetic into the 1st metatarsophalangeal joint may also settle symptoms.
The plantar fascia originates proximally from the medial tubercle of the calcaneum and inflammation around this origin leads to pain on walking. A common cause of heel pain is plantar fasciitis, which may affect almost all ages, but is seen most often in middleaged women and younger (predominantly male) runners. Many of the patients are overweight. Entrapment of the nerve to abductor digiti quinti can also occur. Typically, patients have pain on bearing weight first thing in the morning, the pain then subsides and returns later in the day with walking and standing. Tenderness is present on palpation over the medial plantar insertion of the fascia. A calcaneal spur may be seen on a lateral radiograph, but such spurs are also observed in patients without heel pain. The differential diagnosis may include a stress fracture of the calcaneum. If a positive Tinel’s sign (see ‘Brachial plexus injury’, CROSS REFERENCES) is present over the tarsal tunnel, then a tarsal tunnel syndrome may be suspected. However, this usually causes a burning pain on the sole of the foot, rather than heel pain. Treatment consists of: • shock-absorbent heel pads • stretching of the tendo Achilles (if tight) SURGERY
5 Radiograph showing Scarfe osteotomy of 1st metatarsal.
47
© 2004 The Medicine Publishing Company Ltd
ORTHOPAEDIC SURGERY
the metatarsal heads. Sometimes a click (Mulder’s click) can be elicited with this; this sign is positive only if it elicits pain. The diagnosis is clinical, because ultrasound and MRI are unreliable unless the neuroma is sizeable. Calling this condition a neuroma is inappropriate as the fusiform swelling found at surgery is due to degenerative, not proliferative, changes. Treatment: conservative treatment consists of insoles or injection of corticosteroid; surgical excision relieves the pain, but leaves numbness in the toes.
Lesser toes The lesser toes have an important role in balance and in reducing the weight-bearing load under the metatarsal heads. With age, and systemic diseases (e.g. rheumatoid arthritis), toes may become deformed and lose function. There are three main toe deformities and defining them often causes confusion. A hammer toe is neutral or extended at the metatarsophalangeal joint, flexed at the proximal interphalangeal joint and extended at the distal interphalangeal joint. A hammered 2nd toe is not infrequently seen with hallux valgus because the valgus great toe pushes the 2nd toe into a crowded position. The patient complains of pain and rubbing on the toe box of the shoe from the bony prominence of the proximal interphalangeal joint. A mallet toe is flexed just at the distal interphalangeal joint and is often seen with a tight flexor tendon. Callosity is seen over the distal interphalangeal joint and the end of the toe and walking on the tip of the toe is painful.
6 Radiograph showing replacement of the 1st metatarsophalangeal joint.
A claw toe is extended at the metatarsophalangeal joint and flexed at the proximal interphalangeal joint and distal interphalangeal joint. Multiple claw toes may be seen in patients who have lost intrinsic muscle function, as in hereditary and motor sensory neuropathy or diabetes. Patients may develop callosities or ulcers over the bony prominences resulting from the deformities. All of these joint deformities may be mobile in the early stages and develop fixed deformities with time.
Operatively, a cheilectomy of the 1st metatarsal (to relieve dorsal impingement), an extension osteotomy of the proximal phalanx and either an arthrodesis or joint replacement may be performed. Joint replacement is in its infancy for the great toe, but early results have shown that replacement is feasible and that the joint functions well (Figure 6).
Metatarsalgia
Treatment Treatment consists of either modifying the footwear to fit the foot or straightening the toes surgically, usually by excising the affected interphalangeal joint and fusing it.
Metatarsalgia is forefoot pain in the region of the metatarsal heads and is a common complaint. It may be due to inflammatory arthritis (e. g. rheumatoid) when the joints become eroded and the lesser toes clawed. The clawing causes the fat pad under the metatarsal heads to be drawn forward, exposing the metatarsal heads and leaving the patient feeling that he is walking with ‘pebbles in his shoes’. Transfer metatarsalgia can occur following surgery; shortening or elevation of one or more metatarsals leads to increased pressure (and hence discomfort) under the remaining metatarsal heads. An interdigital neuroma (Morton’s neuroma) may also cause metatarsalgia. This is due to entrapment of the common digital nerve on the plantar surface of the foot and usually occurs in the 3rd webspace, affecting the 3rd and 4th toes. Neuromas may occur in the 2nd webspace, but are uncommon elsewhere. The patient complains of pain and paraesthesiae radiating into the affected toes, and wearing tight shoes aggravates symptoms. Tenderness may be felt in the interspace, which is exacerbated by squeezing
SURGERY
FURTHER READING Alexander I J. The foot: examination and diagnosis. Edinburgh: Churchill Livingstone, 1997. Mann R A, Coughlin M J. Surgery of the foot and ankle. St Louis: Mosby, 1999. Myerson M. Foot and ankle disorders. Philadelphia: W B Saunders, 2000. CROSS REFERENCES Hassan S, Kay S. Brachial plexus injury. Surgery 2003; 21(10): 262–4. Hunter J B. Clubfoot. Surgery 2004; 22(1): 14–17.
48
© 2004 The Medicine Publishing Company Ltd
Common disorders of the adult foot and ankle Patrick Laing
The foot is a complex structure composed of 26 main bones. It must be supple to absorb shock on landing, support the body in stance phase and turn itself into a rigid lever for propulsion. Modern foot and ankle surgery ranges from arthroscopy to joint reconstruction and replacement. This contribution should be read in conjunction with ‘Degenerative and rheumatoid arthritis (including joint replacement)’, page 32. 1 MRI scan of an osteochondral lesion of talus (arrow).
Sports injuries Ankle sprains are very common and most patients will settle down with simple conservative treatment (ice, compression, elevation). However, about 25% of sprained ankles progress to chronic residual symptoms. This may be because of lateral ligament instability, but may be due to injury to other structures in and around the ankle, e.g. osteochondral lesions of the talus (see below), subluxing peroneal tendons, other injuries to the peroneal or tibialis posterior tendons.
continue to cause symptoms and these can be treated with autologous chondrocyte implantation. A sample of articular cartilage is taken from the knee and grown in the laboratory before being reimplanted into the ankle. This is a new and exciting development which potentially offers the chance to rebuild normal articular cartilage rather than fibrocartilage. Other conditions: loose bodies, osteochondritis dissecans and cheilectomy of anterior tibial spurs (common in footballers) are other conditions which can be dealt with arthroscopically.
The anterior talofibular ligament is the first ligament to tear in inversion injuries. The torn anterior talofibular ligament may lead to scar tissue in the lateral gutter of the ankle, which gives rise to local tenderness and pain on activity. This can be treated arthroscopically. In more severe injuries, the calcaneofibular ligament is also torn and may also tear independently of the anterior talofibular ligament.
Arthritis of the hind and midfoot Primary osteoarthritis of the ankle joint Primary osteoarthritis of the ankle joint is relatively rare and it is more common for arthritis to follow trauma (e.g. ankle or pilon fractures) or to occur secondary to an inflammatory arthropathy (e.g. rheumatoid arthritis). Patients present with a stiff and painful hindfoot and may walk with the foot externally rotated, which allows them to roll off the medial border of the foot. Their walking distance will be limited and they may get pain at night and pain on rising to walk after resting. In addition, they may have deformity with either varus or valgus at the hindfoot.
Torn lateral ligaments are treated conservatively, first with peroneal strengthening and wobble-board exercises. If instability persists, then either a direct repair of the anterior talofibular and calcaneofibular ligaments of the ankle (Brostrum–Gould repair) may be performed or part of peroneus brevis used to substitute for the lateral ligaments. Osteochondral lesions of the talus are localized defects of the articular cartilage and underlying bone which may cause ongoing pain (Figure 1). They are usually treated with arthroscopic debridement and the lesions fill in with fibrocartilage. Larger lesions may
Treatment: conservative treatment may consist of: • physiotherapy • corticosteroid injections • orthotic support. Arthroscopic debridement has a limited role surgically and the main operative treatment is either an arthrodesis or arthroplasty. Following an ankle arthrodesis, patients generally walk with a good gait. However, non-union rates of 10–15% are not uncommon. Arthrodesis may also be performed arthroscopically if deformity is minimal and may offer a better and quicker rate of union. The
Patrick Laing is a Consultant Orthopaedic Surgeon at Wrexham Maelor Hospital, Wrexham, UK, and the Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, UK.
SURGERY
45
© 2004 The Medicine Publishing Company Ltd
ORTHOPAEDIC SURGERY
2 Radiograph showing total ankle replacement (note screws from fixation of previous lateral malleolar fracture).
3 Valgus hindfoot in patient with ruptured tibialis posterior tendon.
optimum position is neutral for dorsiflexion/plantarflexion and about 5° of valgus and external rotation. Arthrodesis of one joint will put strain on neighbouring joints and, if subtalar arthritis is present before ankle arthrodesis, it may progress. Ankle joint replacements usually consist of metal tibial and talar components with an interposition polyethylene spacer, and give prosthesis survival rates of 85% after 15 years (Figure 2).
lateral malleolus due to impingement. The forefoot is abducted and externally rotated. Hence, when observing the foot from behind, one sees more toes on the affected foot than on the normal foot (‘too many toes’ sign, Figure 3) and the heel does not invert when the patient is asked to stand on tiptoe. Treatment: in the early stages, tenosynovitis may be treated conservatively with: • physiotherapy • NSAIDs • cast immobilization • orthotic support. If unresponsive, surgical treatment with decompression of the tendon sheath and synovectomy may be necessary. If the tendon is ruptured, reconstruction is possible using part of tibialis anterior or the long flexors, often combined with a calcaneal osteotomy. The prerequisite for this is a mobile foot. In long-standing deformity, fixed supination of the forefoot develops and a triple arthrodesis is usually necessary to give a plantigrade foot.
Arthritis of the subtalar, talonavicular or calcaneocuboid joints Arthritis of the subtalar, talonavicular or calcaneocuboid joints may occur primarily, but usually follows trauma or inflammatory arthritis (e.g. rheumatoid). Subtalar arthritis may follow talar fractures or intra-articular fractures of the calcaneum. Patients often complain of ankle pain and commonly have pain whenwalking over rough ground. Patients with talonavicular arthritis usually locate the pain over the dorsum of the foot. Sometimes it may be difficult to ascertain which joint is causing the patient’s main symptoms and selective local anaesthetic injections, under radiographic guidance, may be helpful. However, communication between joints is not uncommon.
Cavus foot
Treatment: conservative treatment is similar to that given for arthritis of the ankle; arthrodesis is the surgical treatment. Arthrodesis of any one of these joints reduces movement in the others and an isolated subtalar arthrodesis gives the best functional results. When performing a subtalar fusion, the hindfoot should be placed in slight valgus to maintain mobility in the transverse tarsal joints. A fusion of the subtalar, talonavicular and calcaneocuboid joints is known as a triple arthrodesis; if the ankle joint is also arthrodesed, this is known as a pantalar fusion.
The opposite of a flatfoot is a cavus or high-arched foot. The cause is usually idiopathic, but can occur because of: • neuromuscular disorders, e.g. hereditary sensory and motor neuropathy or spinal dysraphism • residual clubfoot deformity (see CROSS REFERENCES) • trauma. Muscular imbalance may lead to a plantarflexed 1st ray, which causes a varus heel and a pes cavo-varus deformity. Patients with a varus heel are prone to recurrent lateral ligament sprains and occasionally this may be the mode of presentation. In association with the high arch, there is often marked clawing of the toes and patients complain of difficulty finding comfortable footwear. Initial investigation should establish the cause of cavus foot.
Adult-acquired flatfoot deformity The tibialis posterior tendon is second only to the Achilles tendon in strength, yet has a short excursion (2 cm). The tibialis posterior tendon inverts and plantarflexes the foot. Dysfunction and attrition ruptures may occur, predominantly in middle-aged females, leading to a progressive flatfoot deformity with valgus of the hindfoot. Initially, patients get medial pain along the tendon and, following tendon rupture, may then develop pain under the tip of the
SURGERY
Treatment: most patients are treated orthotically. Surgical treatment varies according to individual cases, and ranges from toe straightening to tendon transfers, osteotomies and fusions. 46
© 2004 The Medicine Publishing Company Ltd
ORTHOPAEDIC SURGERY
• ultrasound-guided corticosteroid injections. Surgery may have a role, but results vary greatly; a number of reports have shown that extra-corporeal shock wave therapy can be very effective in plantar fasciitis.
Hallux valgus Hallux valgus, a lateral deviation of the hallux, is a common deformity in shod populations, but far less common in those who do not wear shoes. There is a strong family history in over 50% of patients, although the cause is multifactorial. The bunion is the prominent medial eminence of the 1st metatarsal and patients experience pain, particularly when wearing tight shoes. The ‘mirror image’ of a bunion is sometimes seen at the 5th metatarsal, when it is known as a bunionette (tailor’s bunion). This can be very uncomfortable, especially in association with a bunion.
4 Neuropathic diabetic foot ulcer.
Treatment: conservative treatment is shoewear modification to accommodate the deformities. Operative treatment will depend on the degree of deformity and the angle of the joint. Smaller deformities may be treated with a distal metatarsal osteotomy (e.g. Chevron). Larger deformities require release of the tight lateral soft tissues, along with a proximal 1st metatarsal osteotomy. No single operation is suitable for all types of deformity. In recent years, the Scarfe osteotomy has gained popularity in the UK due to its versatility (Figure 5).
Diabetic feet Diabetic feet are liable to ulceration because of the diabetic complications of neuropathy and peripheral vascular disease. Peripheral and autonomic neuropathy lead to a dry, insensitive cavus foot with clawed toes. Patients develop high pressures under the metatarsal heads on walking. The neuropathic foot is often well perfused and ulceration occurs because of the high pressures and unperceived injury (Figure 4). Ulcerated infection may supervene, leading to cellulitis and deep infection with osteomyelitis. The patient is then at risk of amputation.
Hallux rigidus Simple hallux valgus usually causes pain only in patients wearing shoes. Patients who complain of pain walking barefoot, as well as in shoes, and aching at night should be suspected of arthritis in the 1st metatarsophalangeal joint. On examination, there is pain on compression and rotation of the joint and there may be limited movement, i.e. hallux rigidus. The initial movement lost is usually dorsiflexion.
Treatment: simple ulcers may be treated by reducing the pressures in a total contact cast and, once healed, maintaining low pressures with appropriate insoles and footwear. Surgery may be necessary to treat acute infection or recurrent ulceration when fixed deformity is present.
Heel pain
Treatment: a painful hallux rigidus can be treated conservatively by stiffening the shoe shank and adding a rocker; injection of corticosteroid and local anaesthetic into the 1st metatarsophalangeal joint may also settle symptoms.
The plantar fascia originates proximally from the medial tubercle of the calcaneum and inflammation around this origin leads to pain on walking. A common cause of heel pain is plantar fasciitis, which may affect almost all ages, but is seen most often in middleaged women and younger (predominantly male) runners. Many of the patients are overweight. Entrapment of the nerve to abductor digiti quinti can also occur. Typically, patients have pain on bearing weight first thing in the morning, the pain then subsides and returns later in the day with walking and standing. Tenderness is present on palpation over the medial plantar insertion of the fascia. A calcaneal spur may be seen on a lateral radiograph, but such spurs are also observed in patients without heel pain. The differential diagnosis may include a stress fracture of the calcaneum. If a positive Tinel’s sign (see ‘Brachial plexus injury’, CROSS REFERENCES) is present over the tarsal tunnel, then a tarsal tunnel syndrome may be suspected. However, this usually causes a burning pain on the sole of the foot, rather than heel pain. Treatment consists of: • shock-absorbent heel pads • stretching of the tendo Achilles (if tight) SURGERY
5 Radiograph showing Scarfe osteotomy of 1st metatarsal.
47
© 2004 The Medicine Publishing Company Ltd
ORTHOPAEDIC SURGERY
the metatarsal heads. Sometimes a click (Mulder’s click) can be elicited with this; this sign is positive only if it elicits pain. The diagnosis is clinical, because ultrasound and MRI are unreliable unless the neuroma is sizeable. Calling this condition a neuroma is inappropriate as the fusiform swelling found at surgery is due to degenerative, not proliferative, changes. Treatment: conservative treatment consists of insoles or injection of corticosteroid; surgical excision relieves the pain, but leaves numbness in the toes.
Lesser toes The lesser toes have an important role in balance and in reducing the weight-bearing load under the metatarsal heads. With age, and systemic diseases (e.g. rheumatoid arthritis), toes may become deformed and lose function. There are three main toe deformities and defining them often causes confusion. A hammer toe is neutral or extended at the metatarsophalangeal joint, flexed at the proximal interphalangeal joint and extended at the distal interphalangeal joint. A hammered 2nd toe is not infrequently seen with hallux valgus because the valgus great toe pushes the 2nd toe into a crowded position. The patient complains of pain and rubbing on the toe box of the shoe from the bony prominence of the proximal interphalangeal joint. A mallet toe is flexed just at the distal interphalangeal joint and is often seen with a tight flexor tendon. Callosity is seen over the distal interphalangeal joint and the end of the toe and walking on the tip of the toe is painful.
6 Radiograph showing replacement of the 1st metatarsophalangeal joint.
A claw toe is extended at the metatarsophalangeal joint and flexed at the proximal interphalangeal joint and distal interphalangeal joint. Multiple claw toes may be seen in patients who have lost intrinsic muscle function, as in hereditary and motor sensory neuropathy or diabetes. Patients may develop callosities or ulcers over the bony prominences resulting from the deformities. All of these joint deformities may be mobile in the early stages and develop fixed deformities with time.
Operatively, a cheilectomy of the 1st metatarsal (to relieve dorsal impingement), an extension osteotomy of the proximal phalanx and either an arthrodesis or joint replacement may be performed. Joint replacement is in its infancy for the great toe, but early results have shown that replacement is feasible and that the joint functions well (Figure 6).
Metatarsalgia
Treatment Treatment consists of either modifying the footwear to fit the foot or straightening the toes surgically, usually by excising the affected interphalangeal joint and fusing it.
Metatarsalgia is forefoot pain in the region of the metatarsal heads and is a common complaint. It may be due to inflammatory arthritis (e. g. rheumatoid) when the joints become eroded and the lesser toes clawed. The clawing causes the fat pad under the metatarsal heads to be drawn forward, exposing the metatarsal heads and leaving the patient feeling that he is walking with ‘pebbles in his shoes’. Transfer metatarsalgia can occur following surgery; shortening or elevation of one or more metatarsals leads to increased pressure (and hence discomfort) under the remaining metatarsal heads. An interdigital neuroma (Morton’s neuroma) may also cause metatarsalgia. This is due to entrapment of the common digital nerve on the plantar surface of the foot and usually occurs in the 3rd webspace, affecting the 3rd and 4th toes. Neuromas may occur in the 2nd webspace, but are uncommon elsewhere. The patient complains of pain and paraesthesiae radiating into the affected toes, and wearing tight shoes aggravates symptoms. Tenderness may be felt in the interspace, which is exacerbated by squeezing
SURGERY
FURTHER READING Alexander I J. The foot: examination and diagnosis. Edinburgh: Churchill Livingstone, 1997. Mann R A, Coughlin M J. Surgery of the foot and ankle. St Louis: Mosby, 1999. Myerson M. Foot and ankle disorders. Philadelphia: W B Saunders, 2000. CROSS REFERENCES Hassan S, Kay S. Brachial plexus injury. Surgery 2003; 21(10): 262–4. Hunter J B. Clubfoot. Surgery 2004; 22(1): 14–17.
48
© 2004 The Medicine Publishing Company Ltd