Posterior dislocation of the Oxford knee meniscal bearing: a treatment option.

Unicompartmental knee replacement (UKR) is now established as a treatment for medial compartment arthritis. The Oxford UKR (Biomet Orthopedics, Inc, Warsaw, IN, USA) has a mobile-bearing system, which minimizes wear. This has been shown to provide excellent long-term results. Dislocation of the mobile-bearing device is rare with an incidence of 1 in 200 (0.5 %). The treatment usually involves exploration of the knee through the original anteromedial incision, removal of the dislocated bearing and rectification of the underlying cause for the dislocation. We describe two cases of a posterior dislocation in which the mobile bearing could not be retrieved and was left in situ. In both cases a good outcome was achieved. We conclude that in extremely rare cases where a dislocated bearing has migrated posteromedially and cannot be retrieved, it can be left in place rather than exploring the joint acutely through a separate posterior incision.

Acute calcific tendinitis of the popliteus tendon--an unusual site and clinical syndrome.

Three cases of acute calcific tendinitis of the popliteus tendon presenting in the accident and emergency department as 'locked knee' are described. All patients presented with acute pain, flexion deformity and marked limitation of movements of the knee. All patients were unable to weight-bear on the affected side. The radiographs revealed well circumscribed calcification in two patients and faint stippled calcification in the third. All patients were referred to the next fracture clinic with a diagnosis of a mechanical problem within the knee joint due either to a 'loose body' or a meniscal tear. All patients responded to an injection of corticosteroids and local anaesthetic with immediate pain relief and lasting resolution of symptoms.

The pneumatic tourniquet in arthroscopic surgery of the knee.

In a randomized study 56 patients undergoing arthroscopic surgery of the knee were randomly allocated to one of 2 groups: surgery with a tourniquet and surgery without a tourniquet. No significant difference was found between the 2 groups with regard to operating times, technical intraoperative difficulties, identification of intraarticular structures, postoperative pain or postoperative complications. In neither group was the procedure abandoned due to technical difficulties. The pain scores in the non-tourniquet group were lower than those in the group of patients operated on with the use of a pneumatic tourniquet. The study suggests that the use of a tourniquet in arthroscopic surgery of the knee is unnecessary.

The Oxford club-foot programme.

We treated 63 club feet in 44 patients by a defined programme of strapping from birth followed by one of two operations performed at six weeks, either a simple calcaneal tendon lengthening or a subtalar realignment, and reviewed them prospectively. The decision as to which operation to perform was taken at four weeks after radiographic measurement of the talocalcaneal angle. All but eight patients (ten feet) were followed for a mean of 8.7 years. The overall results after calcaneal tendon lengthening were satisfactory. The re-operation rate after subtalar realignment was high (39%) due to over or undercorrection of the deformity.

Soft tissue surgery in Charcot-Marie-Tooth disease.

Ten patients with Charcot-Marie-Tooth disease have been reviewed at an average of 14 years after soft tissue procedures to correct foot deformities. No patient has so far required triple arthrodesis and the overall results as regards function, appearance and symptoms are satisfactory in all patients. It is concluded that soft tissue procedures can certainly postpone the need for triple arthrodesis and in many cases may obviate it altogether.

Unicompartmental Oxford Meniscal knee arthroplasty.

Unicompartmental knee arthroplasty is an attractive concept, but some reports on its use are unfavorable. A meniscal bearing prosthesis has many advantages in this mode of arthroplasty. The authors present preliminary results of 25 unicompartmental knee replacements done with the Oxford Meniscal knee, with a follow-up period of 12-54 months (mean, 21 months). They discuss the scientific basis of unicompartmental knee arthroplasty, which they conclude may be the most appropriate treatment for selected cases of degenerative arthritis of the knee.

Treatment of giant cell tumour of the femoral head and neck.

Giant cell tumours of the femoral head and neck treated at the Nuffield Orthopaedic Centre between 1970 and 1982 were reviewed to evaluate the effectiveness of primary treatment by curettage and bone grafting. All 4 cases recurred within two years, necessitating the likelihood of recurrence following curettage and bone grafting, particularly at this anatomical site, is stressed, and the possibility that hip replacement arthroplasty be considered the primary treatment of choice is discussed.

Lumbar intervertebral disc heights in normal subjects and patients with disc herniation.

A method for the measurement of intervertebral disc heights from lateral radiographs obtained in controlled conditions was examined for intra- and interobserver errors. The use of a strict criterion for the positioning of marks on the images of the vertebrae was shown to enable reproducible measurements to be made with a maximum error of 0.7 mm. Measurements of anterior and posterior disc heights and disc depths were made for 11 normal subjects and ten male patients with prolapsed intervertebral discs, while standing upright. The level of the prolapsed discs were shown to have reduced height compared with normal before surgery, and further narrowing 3 months after surgery. The unaffected discs of the patients were the same height as those of the controls. The technique is proposed as suitable for the investigation of the effect on intervertebral discs of procedures such as the injection of chymopapain.

A prospective study of lumbar spinal movements before and after discectomy using biplanar radiography. Correlation of clinical and radiographic findings.

The significance of alteration of lumbar spinal motion in cases of herniated disc was examined using a three-dimensional x-ray technique (biplanar radiography) before and 3 months after discectomy. Fifteen consecutive cases of disc herniation were studied prospectively. Predictions of clinical examination, myelography, and motion study for the level and site of the lesion were correlated with the operative findings for their accuracy in localization of the lesion. Changes in lumbar spinal motion after surgery were also correlated with the clinical results. The clinical and myelographic predictions were similar to previously published studies. The present study showed that patients with a sequestrated or prolapsed disc lesion (as opposed to bulging disc) had an abnormally large lateral bend or axial rotation during flexion and extension at the level above, which reduced after surgery. Primary lumbar spinal motions (flexion and extension) were generally reduced to half of the normal value and were not significantly altered by surgery. The restriction of lumbar spinal motion was not significantly reflected in the clinical results, which were satisfactory in most cases. Discectomy by fenestration and minimal resection of the lamina did not produce instability.

Posterior intertransverse fusion assessed clinically and with biplanar radiography.

Biplanar radiography was used to assess bony union after intertransverse fusion. The patients were assessed clinically and the fusion status was compared with the clinical result. Posterolateral intertransverse fusion was shown to be capable of fusing the motion segment almost completely. However, the strictly measured fusion rate was only 27%, but this increased to 91% when partial fusions were included. The fusion rate from conventional plain films assessed by the radiologist was 82%, which is similar to other reports. On clinical examination, a satisfactory result was obtained in 82%, but there was no clear correlation with fusion status.

Lumbar intervertebral disc and ligament deformations measured in vivo.

The physiologic deformations of the anterior and posterior margins of the annulus fibrosus and the interspinous ligaments were defined in flexion and extension by accurate measurements taken from lateral roentgenograms of the lumbar spines of 11 normal males. The anterior and posterior disc heights were shown to compress and extend up to 35% and 60%, respectively, while the interspinous distance extended up to 369%. In relation to the known mechanical characteristics in vitro, these deformations implied that the soft-tissue elements were lax or in compression during part of the range of motion. Significantly, the interspinous ligament could be active only in the extremes of flexion. These data provide basic information for further studies of the function of the soft parts of the intervertebral joints.

Axial rotation and lateral bending in the normal lumbar spine measured by three-dimensional radiography.

A three-dimensional radiographic technique was used to investigate the ranges of active axial rotation and lateral bending plus the accompanying rotations in the planes other than that of the primary voluntary movements in two groups of normal male volunteers. There was approximately 2 degrees of axial rotation at each intervertebral joint with L3-4 and L4-5 being slightly more mobile. Lateral bending of approximately 10 degrees occurred at the upper three levels, while there was significantly less movement of 6 degrees and 3 degrees at L4-5 and L5-S1, respectively. In the upper lumbar spine, axial rotation to the right was accompanied by lateral bending to the left and vice versa. At L5-S1, axial rotation and lateral bending generally accompanied each other in the same direction, while L4-5 was a transitional level. These measurements in vivo demonstrated that there was no simple mechanical coupling of the rotations, and that the lordotic shape of the lumbar spine together with muscular control are probably the two principal factors determining the relation between the primary and accompanying rotations.

The radiolucent line beneath the tibial components of the Oxford meniscal knee.

Radiolucent lines at the bone-cement interface beneath the tibial components were assessed in 91 consecutive Oxford meniscal knee replacements in 78 patients. Of 80 knees in which radio-opaque cement was used, a radiolucent line was observed in 77, with a radiodense line in the bone immediately adjoining. Radiolucent lines developed in the majority of patients within one year after operation. In 11 knees fixed with radiolucent cement (which precluded assessment of the radiolucent line) a radiodense line was observed beneath the lucent cement in all cases. Histological examination of the interface obtained from secure tibial components showed the lucent zone to be composed of fibrocartilaginous connective tissue and the radiodense line to be a thick lamella of bone. It is suggested that the living bone under a rigid prosthesis requires a layer of relatively compliant fibrocartilaginous material at its interface to accommodate load-bearing. Attention is drawn to the importance of the radiodense line: its presence may constitute positive evidence that healing at the level of bone section is complete and that equilibrium is established; its absence at a mature interface may indicate disequilibrium and impending failure.