We studied 56 patients with fractures of the tibial shaft in a multicentre prospective randomised trial of three methods of external fixation. Group I was treated with a fixator which was unlocked at 4 to 6 weeks to allow free axial compression (axial dynamisation) with weight-bearing. Group II was treated with a fixator that was similarly unlocked at 4 to 6 weeks but included a small silicone spring which on weight-bearing could be compressed by up to 2 mm. this spring returns to its original length on cessation of weight-bearing thus allowing cycles of motion of up to 2 mm. Group III had a spring fixator like group II, but it was unlocked from the start to allow cyclical micromovement as soon as weight-bearing began. Fracture healing was monitored by the measurement of fracture stiffness. We defined healing as achieving a stiffness of 15 Nm per degree. The mean time was 14.1 weeks in group I, 15.9 weeks in group II, and 19.3 weeks in group III. The difference between groups was statistically significant (p = 0.004). The 95% confidence intervals for the average delay in healing with early cyclical micromovement (group III) as compared with later axial dynamisation (group I) was 1.8 to 8.7 weeks. The healing time in patients whose cyclical micromovement was delayed for 4 to 6 weeks (group II) was between these two extremes, but the differences from either of the other groups could have been due to patient selection. In the patients who completed the full trial, there were pin-track infections in over 60% of those in the cyclical micromovement groups compared with 20% in the axial dynamisation group (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

We describe a rare form of congenital snapping knee. In six knees in four children, the tibia subluxed anteriorly on the femur when the knee was extended and reduced spontaneously on flexion. The abnormal movements were seen and felt as sudden snaps or clunks at about 30 degrees of flexion. All six knees showed similar dysplastic features, although the patients had different clinical syndromes. The mechanism of the subluxation and its management are discussed.

Four children are described, each with spontaneous osteonecrosis affecting nearly one-third of the lateral femoral condyle. All the children had a motor and a sensory deficit in the affected limb: two had been previously treated for neuroblastoma of the spine, one for an infected lumbar dermoid cyst and one had spina bifida. We consider that these disorders, singly or in combination, may lead to repeated excessive loading of the lateral femoral condyle, which cannot be appreciated in a knee that is not protected by normal sensation.

The clinical and radiological features of 12 knees (10 patients) with congenital absence of the anterior cruciate ligament are presented. The high frequency of this condition in association with other more easily recognised congenital abnormalities of the knee is discussed. It is concluded that congenital absence of the anterior cruciate ligament is more common than generally suspected and is associated with other developmental abnormalities of both bone and soft tissue in the lower limb, particularly around the knee joint.

Avulsion of the distal pole of the patella in spastic children with a flexed knee gait may upset the equilibrium of the knee and cause deterioration in walking. We emphasise the clinical features, discuss the mechanism and outline the principles of treatment.

Thirty-two contractures of the quadriceps induced by injection in 17 children have been reviewed. The average age at presentation was 3 years 4 months. All the children had suffered a severe illness within the first few weeks of life and all had received intramuscular injections into the thigh. Three methods of treatment were used: conservative, distal quadricepsplasty, and proximal release. At follow-up none of the patients treated by proximal release had an extension lag, which was present in 70% of those treated by distal quadricepsplasty. Apart from one case with slight improvement in the range of knee flexion, conservative treatment, at best, could only prevent further loss. The clinical presentation and management is described, and the advantages of proximal release are discussed.

A subjective, objective and radiographic study of 21 patients with comminuted calcaneal fractures showing severe involvement of the subtalar joint is reported. The average follow-up was 14.6 years (range 8 to 29 years). Only patients with unilateral closed fractures and no associated injuries to either lower limb were admitted to the study. All were treated by early active mobilisation of the ankle, and the subtalar and the midtarsal joints. Seventy-six per cent of the patients achieved a good result with minor symptoms which did not interfere with their occupation or leisure requirements. Although two-thirds of the patients reached a point of maximal recovery at two to three years, 24% continued to improve for six years. None of the patients experienced any deterioration after this time. Neither the degree of clinical stiffness nor the degeneration of the subtalar joint, assessed radiographically, correlated with the severity of symptoms or functional disability. The role of the soft tissues in the aetiology of residual symptoms is discussed.

Ligamentous instability of the ankle joint can be confirmed by radiographs taken in two planes. The place of the anteroposterior varus stress view is established, but the lateral view which shows anterior subluxation of the talus is frequently omitted. The anatomical significance of the two stress views has been determined by dividing different components of the lateral ligament of 20 cadaveric ankles and noting the subluxation that resulted from these procedures. A clinical assessment was then made of 54 ankles (46 patients) with radiological evidence of instability when subjected to varus and anterior stress. Anterior subluxation was found to be considerably more common than varus tilt, and it is therefore suggested that the lateral stress view should be an essential part of the investigation of the unstable ankle.

Thirty-seven patients have been reviewed after arthrodesis of the ankle in order to determine the reduction of dorsiflexion and plantarflexion of the foot, the incidence of tarsal hypermobility and its relevance to the clinical results of this procedure. Radiological methods of measuring movements in the foot and tarsus are described and applied to patients who had a normal foot on the opposite side which could be used as a control. Our findings suggest that tarsal hypermobility is not as common as has hitherto been supposed and that a stiff foot with minor radiological degenerative changes in the tarsal joints is quite compatible with an excellent result.