Patients who had a revision total hip arthroplasty using the Bürch-Schneider anti-protrusio cage (APC) by a single surgeon have been reviewed after a minimum of five years. There were 63 operations in 58 patients with an average age of 63 years (41 to 83) at the time of revision. At an average follow-up of 8.5 years (5 to 18), 15 patients (25.9%) rated their results as excellent, 38 (65.5%) as good, and five (8.6%) as fair. Five further revisions of the acetabular prosthesis were required, three due to aseptic loosening, one for recurrent dislocation and one due to sepsis. Of the remainder, one was definitely loose, two probably loose, and 12 possibly so.

Impressive augmentation of bone stock can be achieved with the anti-protrusio cage, while enabling the hip to be centred in its anatomical position.

The extent of necrosis is the main determining factor in the outcome of osteonecrosis of the femoral head and is best measured by MRI.

Using statistical analyses, we have evaluated the accuracy and repeatability of seven different methods of measuring the extent of necrosis, of which three demonstrate good or acceptable accuracy. For the general observer their repeatability is poor; only for experienced observers were they reasonable. We conclude that within an institution or for personal use, the accuracy of some methods is acceptable, and repeatability reasonable. None is appropriate for international use.

We carried out percutaneous, arthroscopically- and fluoroscopically-assisted osteosynthesis of fractures of the tibial plateau in 52 patients, of whom 38 were assessed using the HSS knee score and standing radiographs. We reviewed 31 AO type-B fractures and seven type-C fractures after a mean follow-up of five years (1 to 14). Fixation was achieved using percutaneous screws and/or an external frame; 33 associated intra-articular injuries, diagnosed in 21 out of the 38 patients, were treated arthroscopically.

Subjectively, 94.7% of the patients reviewed were satisfied. According to the HSS knee score 78.9% of the results were excellent, 13.2% good, 7.9% fair and none was poor. Narrowing of the joint space was found in 28.9% of the injured and 5.3% of the unaffected knees and axial deviation of 5° to 10° in 15.8% of the injured and 10.5% of the unaffected knees.

Of the 52 fractures, reduction was incomplete in one, and in two secondary displacement occurred, of which one required corrective osteotomy. Deep-venous thrombosis occurred in four cases.

The technique has proved to be safe but demanding. It facilitates diagnosis and appropriate treatment of associated intra-articular lesions.

Between 1989 and 1993 we implanted a matrix support prosthesis made of carbon fibre for the treatment of chronic painful articular defects of the patella in 27 patients. The mean period of follow-up was 33 months (11 to 54) with clinical and arthroscopic evaluation of the implant.

Overall, there were four excellent, three good, seven fair and 13 poor results. Nine patients subsequently had a patellectomy for persistent pain at a mean of 27 months after surgery (14 to 47). The mean visual analogue pain scores in those who retained their patella were 7.6 before operation and 5.5 at the time of the latest follow-up. Patient satisfaction for the entire group was 41%.

There appeared to be good incorporation of the prosthesis and a satisfactory ingrowth of fibrocartilage, but the poor results in 48% and low patient satisfaction discourage us from recommending the procedure for lesions of the articular cartilage of the patella. The consistent seeding of the joint with carbon-fibre debris and a histiocytic giant-cell reaction in the synovium are also a cause for concern.

Early implants for total knee replacement were fixed to bone with cement. No firm scientific reason has been given for the introduction of cementless knee replacement and the long-term survivorship of such implants has not shown any advantage over cemented forms. In a randomised, prospective study we have compared cemented and uncemented total knee replacement and report the results of 139 prostheses at five years. Outcome was assessed both clinically by independent examination using the Nottingham knee score and radiologically using the Knee Society scoring system.

Independent statistical analysis of the data showed no significant difference between cemented and cementless fixation for pain, mobility or movement. There was no difference in the radiological alignment at five years, but there was a notable disparity in the radiolucent line score. With cemented fixation there was a significantly greater number of radiolucent lines on anteroposterior radiographs of the tibia and lateral radiographs of the femur.

At five years, our clinical results would not support the use of the more expensive cementless fixation whereas the radiological results are of unknown significance. Longer follow-up will determine any changes in the results and conclusions.

Many designs of unicompartmental knee replacement show early and mid-term failure due to polyethylene wear. We studied the wear rate of congruent polyethylene meniscal bearings retrieved from failed Oxford unicompartmental knee replacements.

We examined 16 bearings, 0.8 to 12.8 years after implantation, measuring their thickness and comparing it with that of 14 unused bearings. The mean rate of penetration, which included the effects of wear at both upper and lower surfaces, was 0.036 mm per year (maximum 0.08). Bearings as thin as 3.5 mm wore no faster than thicker models, but ten with evidence of impingement had greater wear. The six bearings with no impingement showed a mean rate of penetration of 0.01 mm per year.

In unicompartmental knee replacement, careful implantation of fully congruous meniscal bearings can avoid failure due to polyethylene wear.

Retrieval studies have shown that the use of fully congruent meniscal bearings reduces wear in knee replacements. We report the outcome of 143 knees with anteromedial osteoarthritis and normal anterior cruciate ligaments treated by unicompartmental arthroplasty using fully congruous mobile polyethylene bearings. At review, 34 knees were in patients who had died and 109 were in those who were still living. The mean elapsed time since operation was 7.6 years (maximum 13.8). We established the status of all but one knee.

There had been five revision operations giving a cumulative prosthetic survival rate at ten years (33 knees at risk) of 98% (95% CI 93% to 100%). Considering the knee lost to follow-up as a failure, the ‘worst-case’ survival rate was 97%. No failures were due to polyethylene wear or aseptic loosening of the tibial component. One bearing which dislocated at four years was reduced by closed manipulation.

The ten-year survival rate is the best of those reported for unicompartmental arthroplasty and not significantly different from the best rates for total knee replacement.

We present a case in which the growth of an intraosseous cyst arising from the proximal tibiofibular joint appeared to have been increased by polyethylene wear particles from a medial unicompartmental knee replacement. Histological examination of the cyst wall showed a histiocytic response associated with numerous polyethylene wear particles. This case demonstrates that there is a direct communication between the joint cavity and the cyst. Such communication is probably through openings in the articular cartilage large enough to allow the passage of these particles.

The aim of limb-salvage surgery in malignant bone tumours in children is to restore function and eradicate local disease with as little morbidity as possible. Allografts are associated with a high rate of complications, particularly malunion at the allograft-host junction. We describe a simple technique which enhances union of allograft to host bone taking advantage of the discrepancy in size between the adult allograft and the child’s bone. This involves lifting a flap of periosteum before resection from the host bone, which is then telescoped into the allograft medullary canal, which may require internal burring or splitting, for a distance of 1.5 to 2 cm and covering the bone junction with the periosteal flap. This is more stable than conventional end-to-end opposition. For each centimetre of telescoping the surface area available for bony union is increased more than three times. The periosteal flap also augments union. Additional surface fixation with a plate and screws is not necessary.

We have used this technique in nine children, in eight of whom there was complete union at a mean of 16 weeks. Delayed union, associated with generalised limb osteoporosis, occurred in one. Early mobilisation, with weight-bearing by three weeks, was possible. There was only one fracture of the allograft.

The Sheffield Expanding Intramedullary Rod System was developed after experiencing problems with existing rod systems in the management of osteogenesis imperfecta. Between 1986 and 1996 we treated 74 bones in the lower limb in 28 children at a median follow-up of 5.25 years. We have reviewed 24 children with a total of 60 rods.

Before surgery, all children had had multiple fractures of the lower limb. At review eight patients had experienced no further fractures, but three had suffered five or more subsequently.

Before initial stabilisation, 15 children had never walked, and only three (13%) used walking as their main means of mobility. After surgery, half of those who showed motor arrest were able to walk (p = 0.016). The number of patients able to walk, with or without aids, increased to 17 (p = 0.0001).

We have experienced no evidence of epiphyseal damage after the procedure, and complication rates requiring rod exchange have been low (7%).

We treated 12 patients with multilevel stenosis of the cervical canal after spondylosis or ossification of the posterior longitudinal ligament by an expansive open-door laminoplasty, stabilised by using an anchor system.

The preoperative sagittal diameter of the canal was 9.8 mm(±2.2) which was increased to 16.1 mm (±2.9) after surgery. The mean expansion ratio of the canal was 64% (42 to 100). The anchoring systems did not fail during the follow-up period (mean 29.5 months), and the decompression was maintained. The use of anchor systems to stabilise the posterior elements after laminoplasty is a simple and effective technique for maintaining the increased sagittal diameter of the canal.

We have measured the dynamic movement of the lumbar spine in 57 patients with degenerative lumbar disc disease. Each completed a questionnaire which recorded pain and subjective signs and symptoms. From plain lateral radiographs, the subjects were graded using the criteria of Kellgren and Lawrence and those of Lane et al, which are both based on the severity of degenerative changes. Measurements of the height of the disc space and the vertebral height were obtained and expressed as a ratio.

We found no relationship between the characteristics of spinal movement and the overall grading of degenerative disc disease with either system. Both were influenced (p < 0.01) by age, walking distance, severity of symptoms, drug intake and frequency of pain. The present systems for grading degenerative disc disease from plain lateral radiographs have limited application.

Pain, stiffness, instability and degenerative arthritis are common sequelae of complex fracture-dislocations of the proximal interphalangeal (PIP) joint. Operations were carried out to obtain stability, followed by application of a dynamic external fixator in 20 patients with a mean age of 29 years. This provided stability and distraction, and allowed controlled passive movement. Most (70%) of the patients had a chronic lesion and the mean time from injury to surgery was 215 days (3 to 1953). The final mean range of movement was 12 to 86°.

Complications included redislocation and septic arthritis, which affected the outcome. Four pin-track infections and two breakages of the hinge did not influence the result. The PIP Compass hinge is a useful adjunct to surgical reconstruction of the injured PIP joint.

External fixation is useful for the treatment of selected injuries to the hand. Some authors have suggested that external fixation of a phalanx may tether the extensor hood, thereby hindering active movements and predisposing to permanent adhesions. There is no consensus as to the best site for placement of the pin to minimise these problems. This study was performed on cadaver specimens to investigate the influence of the pin site on the range of simulated active movement of the interphalangeal joint. The dorsal midline position produces least interference with the extensor mechanism; radial and ulnar to this, interdigitating oblique fibres prevent a clean longitudinal split in the direction of gliding thus limiting movement of the extensor hood. At the proximal phalanx, positioning of the pin just off the midline avoids the thickening of the proximal median hood, whereas at the middle phalanx, a true midline position utilises the bare area at its base.

We performed a prospective study in 186 patients with a minimum follow-up of two years in order to attempt to predict successful major re-implantation of the upper limb. There were 137 men and 49 women with 24 amputations of the palm, 75 of the wrist, 50 of the forearm, 9 disarticulations through the elbow, and 28 amputations through the upper arm.

The degree of injury to the amputated segment and the stump were good predictors of the rate of success and the final outcome. Adequate preservation, contraction of the muscle in the amputated part after stimulation, the level of injury and a smoking habit were fair indicators, but the serum potassium concentration in the amputated segment was the best objective predictor. When it is higher than 6.5 mmol/l 30 minutes after re-perfusion, re-implantation should be avoided. A high systemic venous serum potassium concentration was also found before clinical signs of the re-perfusion syndrome were seen.

We have treated 16 patients with recurrent complex elbow instability using a hinged external fixator. All patients had instability, dislocation or subluxation of the ulnohumeral joint. The injuries were open in eight patients and were associated with 20 other fractures and five peripheral nerve injuries. Two patients had received initial treatment from us; 14 had previously had a mean of 2.1 unsuccessful surgical procedures (1 to 6). The fixator was applied at a mean of 4.8 weeks (0 to 9) after the injury and remained on the elbow for a mean of 8.5 weeks (6 to 11). After treatment we found the mean range of flexion-extension to be 105° (65 to 140). At a final follow-up of 23 months (14 to 40), the mean Morrey score was 84 (49 to 96): this translated into one poor, three fair, ten good and two excellent results.

Complications included one fractured humeral pin, one temporary palsy of the radial nerve, one recurrent instability, one wound infection, one severe pin-track infection and one patient with reflex sympathetic dystrophy. Although technically demanding, the use of the fixator is an important advance in the management of recurrent complex elbow instability after failure of conventional treatment.

A primary hydatid cyst in the pelvis is rare, and usually presents with pressure symptoms affecting the adjacent abdominal organs. We describe such a cyst which protruded through the sciatic notch and presented as a gluteal swelling with a foot drop due to compression of the lumbosacral nerve roots. Surgical excision and postoperative treatment with albendazole for six weeks were effective in controlling the disease and preventing recurrence.

We performed one-stage lengthening using intercalary autogenous bone graft in 34 metatarsals and seven proximal phalanges in 21 patients with congenitally short metatarsals. At operation, in order to decrease the tension in the surrounding soft tissues, we gradually distracted the osteotomies of the affected bones for 20 to 30 minutes. The patients, all women, were followed up for a mean period of 2.1 years (1 to 6.5).

The average gain in length for the 34 metatarsal procedures was 14 mm (6 to 21), equivalent to an increase of 32% (11 to 51), and for the seven proximal phalangeal lengthenings 8 mm (5 to 11), an increase of 54% (47 to 65). There was no evidence of neurovascular impairment.

The technique of gradual distraction during operation is simple and effective. It overcomes the disadvantages of one-stage lengthening such as a small gain in length and neurovascular damage.

We have studied 35 patients with infected reconstructions after segmental resection for bone tumours. Two different regimes of treatment were employed both of which entailed debridement and the use of cement impregnated with antibiotic. In 25 patients gentamicin-PMMA beads were used and in ten an antibiotic-impregnated cement spacer. Better results were achieved with the second procedure in terms of cases healed, the number of operations, time of healing, time of recovery and the functional score. The use of vancomycin in the cement spacer gave better local control.

Recent studies of the fibroblast growth factor receptor 3 (FGFR3) gene have established that achondroplasia and hypochondroplasia are allelic disorders of different mutations.

To determine whether the genotype could be distinguished on the basis of the phenotype, we analysed height, arm span, and skeletal radiographs from 23 patients with achondroplasia and the G380R mutation of FGFR3 and eight with hypochondroplasia and the N540K mutation. Both conditions share the classical pathological features of micromelic short stature, reduced or unchanged interpedicular distances in the lumbar spine, disproportionately long fibulae, and squared and shortened pelvic ilia. These were significantly more severe in the G380R patients than in the N540K patients.

Our findings have shown a firm statistical correlation between the genotype and the phenotype, although there were a few exceptional cases in which there was phenotypic overlap between the two conditions.

We performed a crossover study to evaluate the haemodynamic effect of active dorsal to plantar flexion and seven pneumatic compression devices in ten patients who had a total knee arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5MHz linear array probe, we assessed the augmentation of peak venous velocity and venous volume above and below the junction of the greater saphenous and common femoral veins in order to study both the deep and superficial venous systems.

The pneumatic compression devices evaluated included two foot pumps (A-V Impulse System and PlexiPulse Foot), a foot-calf pump (PlexiPulse Foot-Calf), a calf pump (VenaFlow System) and three calf-thigh pumps (SCD System, Flowtron DVT and Jobst Athrombic Pump). The devices differed in a number of ways, including the length and location of the sleeve and bladder, the frequency and duration of activation, the rate of pressure rise, and the maximum pressure achieved. A randomisation table was used to determine the order of the test conditions for each patient.

The enhancement of peak venous velocity occurred primarily in the deep venous system below the level of the saphenofemoral junction. The increases in peak venous velocity were as follows: active dorsal to plantar flexion 175%; foot pumps, A-V Impulse System 29% and PlexiPulse 65%; foot-calf pump, PlexiPulse, 221%; calf pump, VenaFlow, 302% and calf-thigh pumps, Flowtron DVT 87%, SCD System 116% and Jobst Athrombic Pump 263%.

All the devices augmented venous volume, the greatest effect being seen with those incorporating calf compression. The increases in ml/min were found in the deep venous system as follows: foot pumps, A-V Impulse System 9.6 and PlexiPulse Foot 16.7; foot-calf pump, PlexiPulse, 38.1; calf pump, VenaFlow, 26.2; calf-thigh pumps, Flowtron DVT 61.5, SCD System 34.7 and Jobst Athrombic Pump 82.3. Active dorsal to plantar flexion generated 8.5 ml for a single calf contraction.

The direction of wear in the acetabular socket has implications for the amount of debris that is generated during movement, for the magnitude of eccentric loading and for the incidence of impingement of the neck. We observed the direction of penetration with respect to a global co-ordinate system in 84 acetabular components retrieved at reoperation.

The mean direction of wear relative to the open face of the sockets was found to be 37° with a range from 0° to 87°. For those values determined using the inclination of the socket on the prerevision radiograph, the mean direction of penetration in the coronal plane had a lateral, rather than a medial, component. The mean angle was 84° (SD 17°) with respect to the horizontal. The angle of penetration was found to correlate significantly with the depth, in that the lateral component became larger as the wear progressed. There was also a significant correlation between the rate of penetration and the direction of wear. Despite the theoretical advantage of penetration in the superolateral direction, i.e., along the margin of the socket, in reducing the probability of impingement of the neck, no significant correlation was seen between the angle of penetration and the period of use in vivo. This may suggest that impingement of the femoral neck on the rim of the socket may not be the dominant factor in loosening of the socket but can still be important in a few cases.

In normal, physiological circumstances there is ample room in the spinal canal to accommodate the spinal cord. Our study aimed to identify the degree of compromise of the spinal canal which could be anticipated in various atlantoaxial pathological states. We examined paired atlas and axis vertebrae using high-definition radiography and simultaneous photography in both normal and simulated pathological orientations in order to measure the resultant dimension of the spinal canal and its percentage occlusion.

At the extreme of physiological axial rotation (47°) the spinal canal is reduced to 61% of its cross-sectional area in neutral rotation. The spinal cord is thus safe from compromise.

Atlantoaxial subluxation of up to 9 mm reduces the area of the spinal canal, in neutral rotation, to 60% with no cord compromise. Any rotation is, however, likely to cause cord compression.

The mechanism of fixation in atlantoaxial rotatory subluxation could be explained by bony interlocking of the facet joint, reproducible in dry bones.