We studied the development of ball-and-socket deformity of the ankle by arthrography and radiography in 14 ankles of ten patients with congenital longitudinal deficiency of the fibula accompanied by various anomalies. The mean follow-up was for 18 years 10 months.

In three ankles in infants less than one year old the lateral and medial sides of the ankle were already slightly round. In another seven ankles the ball-and-socket appearance developed before the age of five years. This was thought to be due to osseous coalition which limits eversion and inversion. In another four ankles in children who were over the age of one year at the initial examination, the deformity was demonstrated by arthrography and radiography at their first examination.

Ball-and-socket deformity accompanied by tarsal coalition is an acquired deformity secondary to limitation of movement of the subtalar and midtarsal joints. It has completely developed by about five years of age.

Isolated dislocations of the navicular are rare injuries; we present our experience of six cases in which the navicular was dislocated without fracture. All patients had complex injuries, with considerable disruption of the midfoot. Five patients had open reduction and stabilisation with Kirschner wires. One developed subluxation and deformity of the midfoot because of inadequate stabilisation of the lateral column, and there was one patient with ischaemic necrosis. We believe that the navicular cannot dislocate in isolation because of the rigid bony supports around it; there has to be significant disruption of both longitudinal columns of the foot. Most commonly, an abduction/pronation injury causes a midtarsal dislocation, and on spontaneous reduction the navicular may dislocate medially. This mechanism is similar to a perilunate dislocation. Stabilisation of both medial and lateral columns of the foot may sometimes be essential for isolated dislocations. In spite of our low incidence of ischaemic necrosis, there is always a likelihood of this complication.

Percutaneous repair of the ruptured tendo Achillis has a low rate of failure and negligible complications with the wound, but the sural nerve may be damaged. We describe a new technique which minimises the risk of injury to this nerve.

The repair is carried out using three midline stab incisions over the posterior aspect of the tendon. A No. 1 nylon suture on a 90 mm cutting needle approximates the tendon with two box stitches. The procedure can be carried out under local anaesthesia.

We reviewed 27 patients who had a percutaneous repair at a median interval of 35 months after the injury. They returned to work at four weeks and to sport at 16. One developed a minor wound infection and another complex regional pain syndrome type II. There were no injuries to the sural nerve or late reruptures. This technique is simple to undertake and has a low rate of complications.

We have reviewed the long-term results of 22 patients (23 fusions) with fractures of the os calcis, who had subtalar arthrodesis with correction of the deformity between 1975 and 1991. The mean follow-up was nine years (5 to 20).

All patients were evaluated according to a modified foot score. A radiological assessment was used in which linear and angular variables were measured including the fibulocalcaneal abutment, the height of the heel and fat pad, the angle of the arch and the lateral talocalcaneal and the lateral talar declination angles.

The technique used restores the normal relationship between the hindfoot and midfoot and corrects the height of the heel. This leads to better biomechanical balance of the neighbouring joints and gives a favourable clinical outcome.

The modified foot score showed a good or excellent result in 51% of the feet. Residual complaints were mostly due to problems with the soft tissues. Subjectively, an excellent or good score was achieved in 78% of the cases.

After statistical analysis, except for the height of the heel and the degenerative changes in the calcaneocuboid joint, no significant difference was found in the measured variables between the operated and the contralateral side.

We describe in 30 feet the occurrence of a tarsal tunnel syndrome caused by a ganglion. The presenting symptom was numbness or pain in the toes and the sole with paraesthesiae in the distribution of the medial plantar nerve in 63% of the patients. Swellings which were not palpable were detected by ultrasonography. Twenty-nine patients were treated by operation. Most ganglia originated from the talocalcaneal joint, and five were associated with a talocalcaneal coalition. The surgical outcome was satisfactory in all patients except one who had a further operation for a recurrence of the ganglion.

Disarticulation has been carried out in ten ankles in nine patients in whom it was not possible to use a heel flap. Four patients were able to walk with a prosthesis which gave satisfactory function. In five who were bedridden, healing was achieved and was of sufficient quality to allow transfers. There was no operative morbidity or mortality.

This technique can be used instead of a transtibial amputation if necrosis or ischaemia of the heel is a contraindication to conventional Syme’s amputation.

We studied prospectively 30 patients who had a Mitchell’s osteotomy secured by either a suture followed by immobilisation in a plaster boot for six weeks, or by a cortical screw with early mobilisation.

The mean time for return to social activities after fixation by a screw was 2.9 weeks and to work 4.9 weeks, which was significantly earlier than those who had stabilisation by a suture (5.7 and 8.7 weeks, respectively; p < 0.001). Use of a screw also produced a higher degree of patient satisfaction at six weeks, and an earlier return to wearing normal footwear. The improvement in forefoot scores was significantly greater after fixation by a screw at six weeks (p = 0.036) and three months (p = 0.024). At one year, two screws had been removed because of pain at the site of the screw head.

Internal fixation of Mitchell’s osteotomy by a screw allows the safe early mobilisation of patients and reduces the time required for convalescence.

We describe a surgical technique for ankle arthrodesis using an anterior approach to the ankle and internal fixation with an anteriorly-placed AO T plate.

A total of 33 patients who had ankle arthrodeses have been followed retrospectively. Thirty-one (94%) of the ankles fused although two patients developed tibial stress fractures. Four patients had a superficial infection which did not prevent union.

The surgical technique is simple, easily reproducible and gives excellent clinical results with a high rate of union.

We used MRI to study a prospective series of 95 patients with inversion injuries of the ankle and no fracture on plain radiographs. We found an incidence of bone bruises of 27%, but these made no difference to the time of return to work, limitation of walking or physical activity, or the clinical outcome scores at three months.

We conclude that bone bruises have very little clinical significance after inversion injuries of the ankle.

We performed distal chevron osteotomy of the second, third, or fourth metatarsal for painful plantar callosities in 19 non-rheumatoid patients (16 women, 3 men; 21 feet); their mean age was 59 years (32 to 85). The mean follow-up was four years (2 to 7).

The overall results were good in 16 feet, fair in two, and poor in three, with four patients still having painful plantar callosities. There was union in all feet, but transfer metatarsalgia developed in three and three required an orthosis.

Distal chevron osteotomy for intractable plantar callosities was successful both clinically and radiologically in most patients.

Recurrent dislocation of peroneal tendons is uncommon and there are few reports of the long-term results after repair. The Singapore operation, first described in 1985, is an anatomical repair based on the Bankart-like lesion seen in the superior peroneal retinaculum.

We reviewed 21 patients after a mean follow-up of 9.3 years, and found no recurrence. Eighteen had good functional results and had returned to their previous levels of vocational and sports activities. The three fair results were due to painful scars or neuromas.

We performed 52 cemented ankle arthroplasties for painful osteoarthritis (OA) (25) or rheumatoid arthritis (RA) (27) using an ankle prosthesis with a near-anatomical design.

We assessed the patients radiologically and clinically for up to 14 years using an ankle scoring system. The preoperative median scores were 29 for the OA group and 25 for the RA group and at ten years were 93.5 and 83, respectively. Six ankles in the OA group and five in the RA group required revision or arthrodesis.

Survivorship analysis of the two groups showed no significant differences with 72.7% survival for the OA group and 75.5% for the RA group at 14 years.

Between 1985 and 1994, 1223 patients with malleolar fractures of the ankle were treated by open reduction and internal fixation with absorbable pins and screws, of whom 74 (6.1%) had an obvious inflammatory foreign-body reaction to the implants. Of these 74, ten later developed moderate to severe osteoarthritis of the ankle despite no evidence of incongruity of the articular surface. The implants used in these patients were made from polyglycolide, polylactide or glycolidelactide copolymer.

The joint damage seemed to be due to polymeric debris entering the articular cavity through an osteolytic extension of an implant track. The ten patients had a long clinical course which included a vigorous local foreign-body reaction, synovial irritation and subsequent degeneration. At a follow-up of three to nine years, ankle arthrodesis had been necessary in two patients and is being considered for another two.

The incidence of these changes in the whole series was 0.8%, which is not high, but awareness of this possible late complication is essential.

We examined seven patients with tarsal tunnel syndrome in one foot caused by talocalcaneal coalition and a ganglion. We excised the coalition and the ganglion in six of them. All the patients had pain, sensory disturbance in the sole, and a positive Tinel’s sign. Older patients with a long history showed atrophy and weakness of the plantar muscles.

Talocalcaneal coalition can be diagnosed on a plain lateral radiograph and an anteroposterior radiograph externally rotated 20°, and confirmed by CT. MRI is also useful for diagnosis. The coalitions were medial, and the ganglion had developed from the incomplete part of the coalition; it was multilocular in some patients.

After resection, there was early pain relief but sensory disturbances and Tinel’s sign persisted. The postoperative results were excellent in one patient, good in four and fair in one.

We studied retrospectively the results in 24 patients (25 feet) who had been treated by subtalar arthrodesis with internal compression for post-traumatic arthritis from 1988 to 1992. Fifteen patients were men (16 feet) and nine (9 feet) were women. Their mean age was 43 years (22 to 68), and the average duration of follow-up was four years (2 to 6). A single compression screw was used in all feet and iliac-crest bone grafting in ten.

Union was achieved in 24 of the 25 feet (96%). Based on a clinical scale the results were excellent in 10 feet, good in 7, fair in 6, and poor in 2 and on the Angus and Cowell score they were good in 19 feet, fair in 4, and poor in 2. The two poor results were due to nonunion in one patient and reflex sympathetic dystrophy in the other. One reoperation was performed for nonunion. Eighteen patients (18 feet) were satisfied with the results, four were satisfied with reservations, and three were dissatisfied. Progressive ankle and midfoot arthritis did not occur in the absence of pre-existing degenerative changes in these joints.

We conclude that isolated subtalar arthrodesis with internal compression was effective treatment for post-traumatic subtalar arthritis. Iliac-crest bone grafting was not routinely required.

We have recently described an extended lateral approach to the hindfoot for the operative treatment of displaced intra-articular fractures of the calcaneum. It has the advantage of avoiding damage to the sural nerve and preserving blood supply to allow prompt healing.

We dissected 15 formalin-preserved cadavers, taking photographs to show the structures of the posterolateral aspect of the hindfoot and ankle. We describe a superficial and a deep triangle: the deep triangle contains a constant posterior peroneal artery which supplies the skin of the posterolateral heel. An approach designed to expose the sural nerve will divide this important artery and cause ischaemia of the posterior skin. The extended lateral approach elevates the sural nerve in a thick flap and preserves the blood supply of the skin.

We have reviewed 150 consecutive patients after the use of this approach to study the indications for operation, the quality of wound healing, any damage to the sural nerve and other complications. We recommend the careful use of this approach. Our understanding of its anatomical basis has allowed us to widen the indications for its use.

We describe a medial midline portal between the tendons of extensor hallucis longus and tibialis anterior for arthroscopy of the ankle. We dissected 20 cadaver specimens to compare the risk of neurovascular injury using this approach with that of using standard arthroscopic portals. Compared with the anterocentral portal, the medial midline was a mean of 11.2 mm further from the nearest branch of the superficial peroneal nerve and 10.3 mm further from the dorsalis pedis artery.

This portal allows good access to the joint surface and intra-articular structures and has a lower risk of injury to the dorsalis pedis artery, deep peroneal nerve or the medial branch of the superficial peroneal nerve.

Acquired flatfoot deformity after injury is usually due to partial or complete tearing of the tendon of tibialis posterior, with secondary failure of the other structures which maintain the medial longitudinal arch. We describe a patient in whom the rupture of the plantar calcaneonavicular (spring) ligament resulted in a clinical picture similar to that of rupture of the tendon of tibialis posterior. Operative repair of the ligament and transfer of the tendon of flexor digitorum gave an excellent result at four years with the patient returning to full sporting activities.

From 1975 to 1990 we performed subtalar or triple arthrodesis on 54 patients; 48 of them were reviewed after a mean follow-up of 10 years (6 to 15). There were 17 subtalar fusions in 14 patients and 37 triple arthrodeses in 28 patients. We assessed tibiotalar ankle function using the criteria of Mazur which gives a points score of a maximum of 100. Radiological evidence of degenerative change was graded on a scale of 0 to 4.

The mean Mazur score was 85 for the subtalar fusions and 78 for the triple arthrodeses. The radiological score showed no degenerative changes in 36 feet (24 triple and 12 subtalar arthrodeses) and an increase of one grade in 14 feet (10 triple and 4 subtalar), of two grades in three feet (all triple arthrodeses) and of three grades in one foot after a subtalar arthrodesis.

We found no statistically significant difference in the radiological score in unilateral fusions between feet with subtalar and triple arthrodeses and the contralateral foot. In all four feet which showed an increase in degenerative changes of two or more grades, there was an abnormality of the tibiotalar joint before the fusion operation. Of the 14 feet which showed an increase of one grade, there was a similar increase on the contralateral side in nine.

Our findings show that subtalar or triple arthrodesis has little adverse influence on the function of the tibiotalar joint, even after many years.

An 18-year-old girl with moderate joint laxity presented with recurrent dislocation of the calcaneocuboid joint in both feet. We achieved successful stabilisation on both sides by reconstruction of the ligaments and capsule using the plantaris tendons.