We report the outcome of 135 knees with anteromedial osteoarthritis in which the Oxford meniscal-bearing unicompartmental arthroplasty was inserted in a district general hospital by a single surgeon. All the knees had an intact anterior cruciate ligament, a correctable varus deformity and the lateral compartment was uninvolved or had only minor osteoarthritis. The mean follow-up was 5.82 years (2 to 12).

Using revision as the end-point, the outcome for every knee was established. Five knees have been revised giving a cumulative rate of survival of the prosthesis at ten years of 94.04% (95% confidence interval 84.0 to 97.8). Knee rating and patient function were assessed using the modified Knee Society scoring system. The mean knee score was 92.2 (51 to 100) and the mean functional score 76.2 (51 to 100).

The survival of the implant is comparable to that reported by the designers of the prosthesis and not significantly different from that for total knee replacement. Unicompartmental knee replacement offers a viable alternative in patients with medial osteoarthritis. Appropriate selection of patients and good surgical technique are the key factors.

We present the histological findings of an extensor mechanism allograft which was used in a total knee arthroplasty two years after implantation. Analysis of the graft was undertaken at four distinct anatomical levels and it was found to be incorporated into host tissue at each level. A wedge of fibrinoid necrosis, probably related to impingement of the graft on the tibial polyethylene insert, was seen. Impingement may play a role in the injury and necrosis of an allograft and may be one mode of failure in an extensor mechanism allograft.

A total of 344 patients underwent bilateral total knee replacement (TKR) using a different prosthesis on each side. Four knee prostheses were used: anterior and posterior cruciate-retaining (ACL-PCL), posterior cruciate-retaining (PCL), medial or lateral pivot (MLP), and posterior cruciate-substituting (PS).

All patients had good or excellent results. The range of movement, relief from pain, alignment, and stability did not vary among any of the prostheses.

Forty-one of 46 patients (89%) preferred the ACL-PCL to the PS knee and 27 of 35 patients (77%) the MLP knee to the PS knee. Of the patients with an ACL-PCL knee on one side and a MLP on the other, an equal number preferred each type. The MLP knee was preferred to the PCL by 34 (79%) patients. PS and PCL knees were preferred equally. Patients with bilateral TKRs preferred retention of both their cruciate ligaments or substitution with a medial or lateral pivot prosthesis.

We reviewed 100 cemented Endo-model rotating-hinge (Waldemar Link GMBH & Co, Hamburg, Germany) total knee replacements in 80 patients with a mean age of 70 years (56 to 85) at a mean post-operative follow-up of 11 years (7 to 15).

Good or excellent results were seen in 91% of knees and survival at 15 years was 96.1%. There were two deep infections, one dislocation and one supracondylar fracture. There were no peri-operative deaths and there was no loosening, malalignment, migration or wear.

We consider this prosthesis to be ideally suited for the replacement of the deformed knee when the use of an unconstrained design may be questionable.

We performed a prospective study of 54 patients (76 knees) who underwent Osteonics series 3000 cruciate-retaining cementless total knee arthroplasty between December 1990 and June 1993. Five patients (seven knees) were lost to follow-up (90.7% completion). One patient required revision at 10.5 years after operation.

The rate of survival was 100% at ten years and 96.7% at 13 years. The mean ten-year knee and function scores were 79 and 59 respectively. Both were significantly better than the pre-operative scores. The range of movement also improved. Although a radiolucent line around the tibial component enlarged in six knees (20.7%) at ten years, the clinical outcome was generally good. In a patient who died after 5.5 years, post-mortem examination of the knee showed no bony ingrowth into the tibial component. Despite poor bony ingrowth, press-fit fixation was satisfactory and good results can be obtained with this cementless, cruciate-retaining prosthesis.

A controlled study, comparing computer- and conventional jig-assisted total knee replacement in six cadavers is presented. In order to provide a quantitative assessment of the alignment of the replacements, a CT-based technique which measures seven parameters of alignment has been devised and used. In this a multi-slice CT machine scanned in 2.5 mm slices from the acetabular roof to the dome of the talus with the subject’s legs held in a standard position. The mechanical and anatomical axes were identified, from three-dimensional landmarks, in both anteroposterior and lateral planes. The coronal and sagittal alignment of the prosthesis was then measured against the axes. The rotation of the femoral component was measured relative to the transepicondylar axis. The rotation of the tibial component was measured with reference to the posterior tibial condyles and the tibial tuberosity. Coupled femorotibial rotational alignment was assessed by superimposition of the femoral and tibial axial images. The radiation dose was 2.7 mSV.

The computer-assisted total knee replacements showed better alignment in rotation and flexion of the femoral component, the posterior slope of the tibial component and in the matching of the femoral and tibial components in rotation. Differences were statistically significant and of a magnitude that support extension of computer assistance to the clinical situation.

Restoration of neutral alignment of the leg is an important factor affecting the long-term results of total knee arthroplasty (TKA). Recent developments in computer-assisted surgery have focused on systems for improving TKA.

In a prospective study two groups of 80 patients undergoing TKA had operations using either a computer-assisted navigation system or a conventional technique. Alignment of the leg and the orientation of components were determined on post-operative long-leg coronal and lateral films.

The mechanical axis of the leg was significantly better in the computer-assisted group (96%, within ±3° varus/valgus) compared with the conventional group (78%, within ±3° varus/valgus). The coronal alignment of the femoral component was also more accurate in the computer-assisted group.

Computer-assisted TKA gives a better correction of alignment of the leg and orientation of the components compared with the conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.

We have reviewed the literature on the anatomy of the posteromedial peripheral ligamentous structures of the knee and found differing descriptions. Our aim was to clarify the differing descriptions with a simplified interpretation of the anatomy and its contribution to the stability of the knee.

We dissected 20 fresh-frozen cadaver knees and the anatomy was recorded using video and still digital photography. The anatomy was described by dividing the medial collateral ligament (MCL) complex into thirds, from anterior to posterior and into superficial and deep layers. The main passive restraining structures of the posteromedial aspect of the knee were found to be superficial MCL (parallel, longitudinal fibres), the deep MCL and the posteromedial capsule (PMC). In the posterior third, the superficial and deep layers blend. Although there are oblique fibres (capsular condensations) running posterodistally from femur to tibia, no discrete ligament was seen. In extension, the PMC appears to be an important functional unit in restraining tibial internal rotation and valgus.

Our aim was to clarify and possibly simplify the anatomy of the posteromedial structures. The information would serve as the basis for future biomechanical studies to investigate the contribution of the posteromedial structures to joint stability.

The aim of our study was to determine the current incidence and outcome of infected total knee arthroplasty (TKA) in our unit comparing them with our earlier audit in 1986, which had revealed infection rates of 4.4% after 471 primary TKAs and 15% after 23 revision TKAs at a mean follow-up of 2.8 years. In the interim we introduced stringent antibiotic prophylaxis, and the routine use of occlusive clothing within vertical laminar flow theatres and 0.05% chlorhexidine lavage during arthroplasty surgery.

We followed up 931 primary TKAs and 69 revision TKAs for a mean of 6.5 years (5 to 8). Patients were traced by postal questionnaire, telephone interview or examination of case notes of the deceased.

Nine (1%) of the patients who underwent primary TKA, and four (5.8%) of those who underwent revision TKA developed deep infection. Two of nine patients (22.2%) who developed infection after primary TKA were successfully treated without further surgery. All four of the patients who had infection after revision TKA had a poor outcome with one amputation, one chronic discharging sinus and two arthrodeses.

Patients who underwent an arthrodesis had comparable Oxford knee scores to those who underwent a two-stage revision. Although infection rates have declined with the introduction of prophylactic measures, and more patients are undergoing TKA, the outcome of infected TKA has improved very little.

A technique for performing allograft-augmented revision total knee replacement (TKR) using computer assistance is described, on the basis of the results in 14 patients. Bone deficits were made up with impaction grafting. Femoral grafting was made possible by the construction of a retaining wall or dam which allowed pressurisation and retention of the graft. Tibial grafting used a mixture of corticocancellous and morsellised allograft. The position of the implants was monitored by the computer system and adjusted while the cement was setting. The outcome was determined using a six-parameter, quantitative technique (the Perth CT protocol) which measured the alignment of the prosthesis and provided an objective score.

The final outcomes were not perfect with errors being made in femoral rotation and in producing a mismatch between the femoral and tibial components. In spite of the shortcomings the alignments were comparable in accuracy with those after primary TKR. Computer assistance shows considerable promise in producing accurate alignment in revision TKR with bone deficits.

A total of 108 patients with unilateral instability of the knee, associated with rupture of the anterior cruciate ligament, was prospectively randomised for arthroscopic single- or double-bundle reconstruction of the ligament using hamstring tendons. The same postoperative rehabilitation protocol was used for all. The patients were followed up for a mean of 32 months (24 to 36). We measured the anterior laxity and joint position sense at different angles of flexion of the knee to determine whether both bundles in the double-bundle reconstruction contributed to the stability of the joint and proprioception.

No significant difference was found between the two groups with regard to anterior laxity measured by the KT-2000 arthrometer with the knee at 20° or 70° flexion nor with regard to proprioception. A notchplasty was required less often in the double- compared with the single-bundle reconstruction.

We did not find any advantage in a double-bundle as opposed to a single-bundle reconstruction in terms of stability or proprioception.

We have compared a new technique of computer-assisted knee arthroplasty with the current conventional jig-based technique in 70 patients randomly allocated to receive either of the methods. Post-operative CT was performed according to the Perth CT Knee Arthroplasty protocol and pre- and post-operative Maquet views of the limb were taken. Intra-operative and peri-operative morbidity data were collected and blood loss measured.

Post-operative CT showed a significant improvement in the alignment of the components using computer-assisted surgery in regard to femoral varus/valgus (p = 0.032), femoral rotation (p = 0.001), tibial varus/valgus (p = 0.047) tibial posterior slope (p = 0.0001), tibial rotation (p = 0.011) and femorotibial mismatch (p = 0.037). Standing alignment was also improved (p = 0.004) and blood loss was less (p = 0.0001). Computer-assisted surgery took longer with a mean increase of 13 minutes (p = 0.0001).

Our study evaluated the accuracy of an image-guided total knee replacement system based on CT with regard to preparation of the femoral and tibial bone using nine limbs from five cadavers. The accuracy was assessed by direct measurement using an extramedullary alignment rod without radiographs.

The mean angular errors of the femur and tibia, which represent angular gaps from the real mechanical axis in the coronal plane, were 0.3° and 1.1°, respectively. The CT-based system, provided almost perfect alignment of the femoral component with less than 1° of error and excellent alignment with less than 3° of error for the tibial component. Our results suggest that standardisation of knee replacement by the use of this system will lead to improved long-term survival of total knee arthroplasty.

We have reviewed 22 patients from a total of 135 treated by autologous chondrocyte implantation (ACI) who had undergone further surgery for pain in the knee and mechanical symptoms after a mean of 10.5 months. There were 31 grafted lesions. At operation the findings included lifting (24/31) and detachment (3/31) of periosteal patches for which arthroscopic shaving was performed. Chondroplasty was undertaken on two new lesions, another required an ACI and a further patient required trimming of a meniscus.

The mechanical symptoms resolved within two weeks. At the last review, two to 14 months from reoperation; 68% had improved, and 86% had normal or nearly normal IKDC scores. Of the 31 lesions, 30 (97%) had normal or nearly normal visual repair scores.

Biopsy showed good integration with subchondral bone and the marginal interface in all specimens, most of which showed hyaline or hyaline-like cartilage (70%). Troublesome mechanical symptoms required surgery in 13% of ACI-treated patients and were attributed to periosteal extrusion. Simple arthroscopic debridement was curative.

We report the five- to-ten year results of Anderson Orthopaedic Research Institute type-2 bone defects treated with modular metal augments in revision knee surgery.

A total of 102 revision knee arthroplasties in patients with type-2 defects treated with augments and stems were prospectively studied. Seven patients (seven knees) had incomplete follow-up and 15 patients (16 knees) died with the arthroplasty in situ. The mean follow-up of the 79 remaining knees was 7 ± 2 years (5 to 11). The presence of non-progressive radiolucent lines around the augment in 14% of knees was not associated with poorer knee scores, the range of movement, survival of the component or the type of insert which was used (p > 0.05). The survival of the components was 92 ± 0.03% at 11 years (95% CI, 10.3 to 11.2).

We recommend the use of modular augmentation devices to treat type-2 defects in revision knee surgery.

We have carried out a prospective study comparing the results at five years in patients older than 75 years of age undergoing hydroxyapatite-coated, cementless total knee replacement (TKR) with those who were younger. The Knee Society clinical rating scores were recorded before and after operation. Of 559 patients undergoing TKR, 135 were in the elderly age group. The knee scores at five years or more showed comparable results, with patients under 75 years of age reaching a score of 183 and those aged 75 years or over reaching 174. These differences were predominantly due to the functional component of the score. We conclude that elderly patients do just as well as the younger group using this prosthesis.

Infection is a potentially disastrous complication of total knee replacement (TKR). Retention of the prosthesis has been associated with high rates of persistent infection. Our study shows that in selected situations, arthroscopic debridement may allow retention of the prosthesis and eradication of the infection. However, the prosthesis must be stable, the surgical technique must be meticulous and specific antibiotics must be taken for a lengthy period. Arthroscopic debridement should be considered as an alternative to an open technique, or revision, for the infected TKR.

Interest in unicompartmental knee arthroplasty (UKA) for the treatment of medial compartment osteoarthritis has increased in recent years with apparent improvement in the long-term results. This is a result of improved surgical technique, patient selection, and implant design. In an effort further to improve patient selection we analysed the relationship between the pre-operative alignment of the knee and the anatomical findings at the time of surgery. We compared these findings with the indications for UKA.

From 4021 total knee arthroplasties we compared intra-operative observations with the pre-operative clinical data in order to identify knees with isolated, medial, compartment changes, which would have been ideal candidates for UKA.

We found that only 247 of the knees (6.1%) met anatomical qualifications for isolated, medial, unicompartmental osteoarthritis, and of these, only 168 (4.3%) met clinical standards ideal for UKA. Pre-operative alignment showed a significant relationship with patterns of disease. Logistic regression revealed a relationship between pre-operative alignment and intra-operative findings resembling a Gaussian distribution. Patients with a pre-operative varus alignment of 7° were slightly more likely to be selected for UKA. But the further the anatomical alignment in either direction varies from 7° of varus, the more unlikely it is for the knee to exhibit a disease pattern of isolated, medial, unicompartmental osteoarthritis.

Axial radiographs were obtained under valgus and external rotation stress at 45° of knee flexion with and without contraction of the quadriceps muscle in order to assess the dynamics of patellar subluxation or dislocation. The radiography was performed on 82 knees in 61 patients with patellofemoral instability, and on 44 normal knees. The lateral patellofemoral angle and the congruence angle were measured and compared with the conventional Merchant views. Both parameters showed greater differences between symptomatic and normal knees on the stress radiographs obtained without quadriceps contraction. There was a major difference in the lateral patellofemoral angles between the groups, which clearly distinguished symptomatic knees from normal controls. Congruence angles on stress radiography had a significant correlation with the functional scores obtained after a period of conservative treatment and a positive correlation with the frequency of patellar subluxation.

When the quadriceps contracted, two patterns of patellar shift were observed. While the patella reduced into the trochlear groove in all normal knees and about 70% of the symptomatic knees, contraction of the quadriceps caused further subluxation of the patella in the remaining symptomatic knees. All the knee joints which showed this displacement failed to respond to conservative treatment and eventually required surgical treatment. Thus, this technique of stress radiography is a simple, cost-effective and useful method of evaluating patellar instability and predicting the prognosis.

Miller-Galante II total knee arthroplasty (MG II TKA) was performed on 32 knees in 30 patients. On both the femoral and tibial components, the fibre-metal area was plasma-sprayed with hydroxyapatite-tricalcium phosphate (HA-TCP). The clinical and radiographic outcome was evaluated. A mean pre-operative knee score of 26.0 ± 18.6 (SD) increased to 97.5 ± 3.5 and a mean pre-operative functional score of 21.7 ± 15.0 (SD) increased to 83.4 ± 12.4 at follow-up of seven years. Clear zones were common around the components at one month post-operatively but had completely disappeared after six months. An autopsy of a patient who underwent MG II TKA with HA-TCP two years previously, showed osteogenesis in all parts of the fibre-metal, and bone tissue comprised 77.7% of the interface. This coated prosthesis has good early fixation which is maintained at seven years with good clinical and radiographic outcomes.

Revision of a total knee arthroplasty may require an extensile approach to permit a satisfactory exposure without compromising the attachment of the patellar tendon. It has been assumed that a rectus snip is a relatively benign form of release, but the effect of using this approach on function, pain and patient satisfaction is not known.

From January 1997 to December 1999, 107 patients who underwent revision of total knee arthroplasty were followed up at a minimum of two years (mean 40.5 months) and assessed by the Oxford Hip Score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Short-Form (SF)-12 and patient satisfaction. Co-morbidity, surgical exposure, the Hospital for Special Surgery (HSS) knee scores and the range of movement were also used. A standard medial parapatellar approach was used in 57 patients and the rectus snip in 50. The two groups were equivalent for age, sex and co-morbidity scores. The WOMAC function, pain, stiffness and satisfaction scores demonstrated no statistical difference. The use of a rectus snip as an extensile procedure has no effect on outcome.

There have been many reports which suggest that in patients with tibiofemoral osteoarthritis, a reduction in joint space is demonstrated better on weight-bearing radiographs taken with the knee in semiflexion than in full extension. The reduction has been attributed to the loss of articular cartilage in the contact area in a semiflexed arthritic knee. None of these studies have, however, included normal knees. We have therefore undertaken a prospective, double-blind, randomised study in order to evaluate the difference in the joint-space of arthroscopically-proven normal tibiofemoral joints as seen on weight-bearing full-extension and 30° flexion posteroanterior radiographs. Twenty-two knees were evaluated and the results showed that there may be a difference of up to 2 mm in the two views. This difference could be attributed to the inherent differential thickness of the articular cartilage in different areas of the femoral and tibial condyles and a change in the areas of contact between them.

The natural history of spontaneous osteonecrosis of the medial tibial plateau remains controversial and incomplete. We have studied 21 patients (aged between 53 and 77 years) with clinical and scintigraphic features of spontaneous osteonecrosis of the medial tibial plateau who were observed prospectively for at least three years (37 months to 8.5 years). The mean duration of follow-up was 5.6 years.

The mean duration of symptoms at presentation was 4.7 weeks (3 days to 12 weeks). Radiographs of the affected knee at the first visit were normal in 15 patients and mildly arthritic in six. The characteristic radiographic lesion of osteonecrosis was noted at presentation in five of the mildly arthritic knees and during the evolution of the disease in eight of the radiographically normal knees. During the follow-up, subchondral sclerosis of the affected medial tibial plateau was noted in 16 knees.

There are three distinct patterns of outcome: 1) acute extensive collapse of the medial tibial plateau in two knees within three months of onset; 2) rapid progression to varying degrees of osteoarthritis in 12 knees, in eight within a year, in all within two years and deterioration of the pre-existing osteoarthritis in three; and 3) complete resolution in four knees, two of which were normal at presentation and two mildly osteoarthritic.

The two patients with acute extensive collapse and three who had rapid progression to severe osteoarthritis required total knee arthroplasty.

We conclude that osteonecrosis of the medial tibial plateau progresses in most cases to significant degenerative disease of the knee.

Between 1986 and 1991, 106 patients (127 knees) underwent uncemented knee arthroplasty for osteoarthritis. There were 106 total knee arthroplasties and 21 medial unicompartmental knee arthroplasties. The arthroplasties were evaluated for aseptic loosening during the year 2000. For total arthroplasty we used 77 porous-coated anatomic prostheses and 29 press-fit condylar prostheses. The mean bone mineral content of the proximal tibia, measured the day before surgery using dual-photon absorptiometry was 5.48 g/cm for the porous-coated anatomic prostheses which were revised for aseptic loosening (n = 9). This was significantly higher (p = 0.02) than the mean of 4.33 g/cm for those which were not revised. Values for the two revised press-fit condylar knees (4.78 and 4.93 g/cm) were above the mean value (4.23 g/cm) for those which were not revised. We found no statistically significant (p = 0.38) difference between the bone mineral content of the 12 revised and nine unrevised unicompartmental arthroplasties. Low trabecular bone quality, measured as the pre-operative bone mineral content of the proximal tibia, was not a predictor for later revision surgery following uncemented total knee or unicompartmental knee arthroplasty.

We treated 21 patients with 22 dislocations of the knee by repair or reconstruction of all injured ligaments. Eight knees were treated in the acute phase (less than two weeks after injury); the remainder were treated more than six months after injury (6 to 72). Reconstructions were carried out with a combination of autograft and allograft tendons and by direct ligament repair where possible. At a mean follow-up of 32 months (11 to 77) the mean Lysholm score was 87 (81 to 91) in the acute group and 75 (53 to 100) in the delayed group. The mean Tegner activity rating was 5 in the acute group and 4.4 in the delayed group.

The International Knee Documentation Committee assessment revealed no differences between the two groups. Instrumented testing of knee stability indicated better results for anterior cruciate ligament reconstructions which had been undertaken in the acute phase, but no difference in the outcome of posterior cruciate ligament reconstructions. There was no difference in the loss of knee movement between the two groups. Although the differences were small, the outcome in terms of overall knee function, activity levels and anterior tibial translation were better in those knees which had been reconstructed within two weeks of injury.

We conducted this prospective randomised and externally evaluated study to investigate whether the use of a navigation system during total knee arthroplasty leads to significantly better results than the hand-guided technique. A total of 240 patients was included in the study. All patients received a condylar knee prosthesis. Two surgeons performed all the operations using the Stryker knee navigation system. Exclusion criteria included the necessity for the primary use of constrained implants.

The results revealed a highly significant difference between the two groups in favour of navigation with regard to the mechanical axis, the frontal and sagittal femoral axis and the frontal tibial axis (p < 0.0001). The use of a navigation system was therefore shown to improve the alignment of the implant.

We investigated the outcome of deep-vein thrombosis (DVT) in the calf after total knee arthroplasty (TKA) in 48 patients (45 women and three men) by clinical assessment and venographic study between three and four years after surgery. The mean age of the patients was 67.2 ± 7.7 years (52 to 85) and the mean follow-up was 42.6 ± 2.7 months (38 to 48). The diagnosis was osteoarthritis in 47 patients and rheumatoid arthritis in one patient. There were 44 calf thrombi, four popliteal thrombi but no thrombi in the femoral or iliac regions. Of the 48 patients, 24 were clinically symptomatic and 24 were asymptomatic. Clinical examination was carried out on 41 patients, of whom 37 underwent ascending venography. Seven were evaluated by telephone interview.

No patient had the symptoms or signs of recurrent DVT, venous insufficiency in the affected leg, or a history of pulmonary embolism. No patient had been treated for complications of their DVT. Thirty-six of the 37 venographic studies were negative for either old or new DVT in the affected leg. One patient had residual thrombi in the muscular branches of the veins.

Our study shows that deep-vein thromboses in the calf after TKA disappear spontaneously with time. No patient developed a recurrent DVT, proximal propagation or embolisation. Treatment of DVT in the calf after TKA should be based on the severity of the symptoms during the immediate postoperative period.

We studied retrospectively the outcome of patellofemoral arthroplasty (PFA) using the Richards prosthesis in 51 patients (56 knees). Their mean age was 50 years (30 to 77). In 43 patients (45 knees), the American Knee Society score and the patients’ subjective judgement were assessed. Excellent or good results were obtained in 86% of cases at a mean follow-up of 17 years (15 to 21).

Because of ongoing tibiofemoral osteoarthritis, two patients required a high tibial osteotomy and ten PFAs were converted to a total knee arthroplasty after a mean of 15.6 years (10 to 21). The PFAs were stable during follow-up with a loosening rate of only 2%.

We conclude that a patellofemoral prosthesis is a good treatment option with successful long-term results in middle-aged patients with radiologically documented, isolated, patellofemoral osteoarthritis.

We report the results of a prospective randomised trial which assessed the role of the posterior cruciate ligament (PCL) following total knee replacement (Genesis I; Smith and Nephew, Memphis, Tennessee). Over a four-year period, 211 patients underwent total knee replacement by the senior author (TJW). They were randomised at surgery to have the PCL either retained, excised or substituted with a posterior stabilised insert. If it was not possible to retain the ligament due to soft-tissue imbalance, it was released from its tibial insertion until suitable tension was obtained. This created a fourth group, those who were intended preoperatively to have the ligament retained, but in whom it was partially released as a result of findings at the time of surgery.

All patients were evaluated using the Knee Society rating system (adapted from Insall). A total of 188 patients (212 knees) was available for follow-up at a mean of 3.5 years after surgery. Preoperatively, there was a varus deformity in 191 knees (90%) and a valgus deformity in 21 (10%).

There were no statistical differences in the knee or function scores or the range of movement between the excised, retained and substituted groups. There were, however, significantly worse knee and function scores in the group in whom the PCL was released (p = 0.002).

Out of a total of 623 patients who, over a ten-year period, underwent primary total knee replacement (TKR) without patellar resurfacing, 20 underwent secondary resurfacing for chronic anterior knee pain.

They were evaluated pre- and postoperatively using the clinical and radiological American Knee Society score. The mean follow-up was 36.1 months (12 to 104). The mean knee score improved from 46.7 to 62.2 points and the mean functional score from 44.7 to 52.2 points. Only 44.4% of the patients, however, reported some improvement; the remainder reported no change or deterioration. The radiographic alignment of the TKR did not influence the outcome of secondary resurfacing of the patella. Complications were noted in six of the 20 patients including fracture and instability of the patella and loss of movement.

Anterior knee pain after TKR remains difficult to manage. Secondary resurfacing of the patella is not advocated in all patients since it may increase patient dissatisfaction and hasten revision.

Free radicals, such as reactive oxygen species (ROS) which are released abruptly after deflation of an ischaemic tourniquet, cause reperfusion injuries. Ischaemic precondition (IPC), however, can reduce the injury. In clinical practice, the sequential application and release of tourniquets is often used in bilateral total knee replacement (TKR) to obtain a clearer operative field, but the effects on the production of free radicals and lipid peroxidation have not been studied.

In this study, we have observed the production of free radicals and the subsequent lipid peroxidation in bilateral TKR with sequential application of a tourniquet to examine the effect of IPC. Patients undergoing elective TKR under intrathecal anaesthesia were studied. Blood samples were obtained after spinal anaesthesia, one minute before and five and 20 minutes after release of each tourniquet. We used the lucigenin chemiluminescence analysis and the phosphatidylcholine hydroperoxide (PCOOH) assay to measure the production of ROS and lipid peroxidation.

Our results showed that production of ROS significantly increased at five and 20 minutes after release of the first tourniquet and at five minutes after release of the second tourniquet, but returned to normal at 20 minutes after the second reperfusion. The peak production of ROS was at 20 minutes after the first reperfusion; lipid peroxidation did not change significantly.

We conclude that in spite of significant production of ROS after the release of tourniquet, the IPC phenomenon occurs during bilateral TKR with sequential application of a tourniquet.

We randomised 31 patients with acute tears of the anterior cruciate ligament (ACL) to receive either early (within 2 weeks) or delayed (8 to 12 weeks) reconstruction using a quadruple hamstring graft in order to determine if there was any functional advantage to early reconstruction. Outcome measures included return of knee movement, muscle dynamometry, International Knee Documentation Committee (IKDC) scores and Tegner activity levels.

Two cases of symptomatic deep-venous thrombosis occurred in the early group. The mean range of movement was significantly greater at two weeks in the delayed group. Quadriceps muscle power was significantly better in the delayed group at 12 weeks (p < 0.05). These trends were evident at later time points, but were not statistically significant. One patient in each group had clinically significant knee stiffness at 52 weeks. IKDC scores and Tegner activity levels were not significantly different at 52 weeks. We conclude that there is no functional advantage to be gained by early reconstruction of the ACL.

We have compared the survival of 67 revision arthroplasties of the knee undertaken for aseptic loosening with and without the retention of a secure, cemented femoral component. All the patients had undergone a single primary procedure at a mean of nine years previously. In group I (25 knees) the original femoral component was secure and was retained. There were no abrasions or osteolysis. The knees were stable, normally aligned, with minimal bone loss. In group II 42 knees did not fulfil these criteria and underwent revision of both components. The mean follow-up was four years.

Re-revision for loosening was required in seven knees (28%) in group I and three (7%) in group II (p < 0.01). The remaining knees function well with Knee Society scores averaging 84/69 and no radiological evidence of osteolysis. When revising cemented implants, retention of a secure femoral component cannot be recommended even when conditions appear to be suitable.

We carried out 60 revision procedures for failed porous coated anatomic total knee replacements in 54 patients, which were divided into two groups. The 14 knees in group I had a well-fixed femoral component at surgery which was retained, and in the 46 knees in group II both tibial and femoral components were loose and were revised using a variety of implants. Our review comprised clinical and radiological assessment.

A total of 13 knees required a second revision. Six (42%) in group I failed very early (mean 2.1 years) when compared with seven (15%) in group II (mean 6.8 years). Failure was due to wear of the polyethylene insert by the abraded, retained femoral component (crude odds ratio 4.07; 95% CI 1.07 to 15.5). We recommend a complete change of primary bearing surfaces at the time of revision of an uncemented total knee replacement in order to prevent early wear of polyethylene.

We randomised 129 knees which were to be replaced using a standard posterior-cruciate-ligament (PCL)-retaining cemented total knee replacement into two groups. In one the PCL was retained in the normal way and in the other it was resected. They were well matched, with a predominance of women, and a mean age of 67 years.

There was no statistically significant difference in the Hospital for Special Surgery scores at a mean of 57 months (56 to 60) between the two groups although 21 patients (24 knees) were lost to follow-up. Relief from pain, correction of deformity, range of movement, stability and strength were comparable in both. Radiological assessment showed femoral rollback in approximately 20% of knees with a slightly higher incidence in the PCL-resected group. There was no significant loosening detected in either group at review at two years.

At five years, one knee in the PCL-retained group had been revised because of infection and one patient in each group was awaiting revision for loosening.

Our findings have shown no significant difference in the five-year results for a PCL-retaining total knee replacement if the PCL is excised or preserved. This suggests two important points. First, the PCL is not functional in most patients with a total knee replacement even when retained. Secondly, patients with an excised PCL show a good result with a PCL-retaining implant, thereby questioning the need for a posterior stabilised design in such a situation.

Total knee replacement and high tibial osteotomy are common orthopaedic operations with low complication rates. Such surgery is in close proximity to the popliteal artery (PA), the behaviour of which during flexion of the knee is poorly understood.

We used Duplex ultrasonography to determine the distance of the PA from the posterior tibial surface at 0° and 90° of flexion in 100 knees. When the knee was flexed the PA was closer to the posterior tibial surface at 1 to 1.5 cm below the joint line in 24% and at 1.5 to 2 cm below the joint line in 15%. There was a high branching anterior tibal artery in 6% of knees. We provide an anatomical account to help to explain our findings by using cadaver dissections, arteriography and static MRI studies.

We prospectively randomised 100 patients undergoing cemented total knee replacement to receive either a single deep closed-suction drain or no drain.

The total blood loss was significantly greater in those with a drain (568 ml versus 119 ml, p < 0.01; 95% CI 360 to 520) although those without lost more blood into the dressings (55 ml versus 119 ml, p < 0.01; 95% CI −70 to 10). There was no statistical difference in the postoperative swelling or pain score, or in the incidence of pyrexia, ecchymosis, time at which flexion was regained or the need for manipulation, or in the incidence of infection at a minimum of five years after surgery in the two groups.

We have been unable to provide evidence to support the use of a closed-suction drain in cemented knee arthroplasty. It merely interferes with mobilisation and complicates nursing. Reinfusion drains may, however, prove to be beneficial.

Autologous chondrocyte implantation (ACI) and mosaicplasty are both claimed to be successful for the repair of defects of the articular cartilage of the knee but there has been no comparative study of the two methods. A total of 100 patients with a mean age of 31.3 years (16 to 49) and with a symptomatic lesion of the articular cartilage in the knee which was suitable for cartilage repair was randomised to undergo either ACI or mosaicplasty; 58 patients had ACI and 42 mosaicplasty. Most lesions were post-traumatic and the mean size of the defect was 4.66 cm². The mean duration of symptoms was 7.2 years and the mean number of previous operations, excluding arthroscopy, was 1.5. The mean follow-up was 19 months (12 to 26).

Functional assessment using the modified Cincinatti and Stanmore scores and objective clinical assessment showed that 88% had excellent or good results after ACI compared with 69% after mosaicplasty. Arthroscopy at one year demonstrated excellent or good repairs in 82% after ACI and in 34% after mosaicplasty. All five patellar mosaicplasties failed.

Our prospective, randomised, clinical trial has shown significant superiority of ACI over mosaicplasty for the repair of articular defects in the knee. The results for ACI are comparable with those in other studies, but those for mosaicplasty suggest that its continued use is of dubious value.

Before proceeding to longer-term studies, we have studied the early clinical results of a new mobile-bearing total knee prosthesis in comparison with an established fixed-bearing device. Patients requiring bilateral knee replacement consented to have their operations under one anaesthetic using one of each prosthesis. They also agreed to accept the random choice of knee (right or left) and to remain ignorant as to which side had which implant. Outcomes were measured using the American Knee Society Score (AKSS), the Oxford Knee Score (OKS), and determination of the range of movement and pain scores before and at one year after operation.

Preoperatively, there was no systematic difference between the right and left knees. One patient died in the perioperative period and one mobile-bearing prosthesis required early revision for dislocation of the meniscal component.

At one year the mean AKSS, OKS and pain scores for the new device were slightly better (p < 0.025) than those for the fixed-bearing device. There was no difference in the range of movement.

We believe that this is the first controlled, blinded trial to compare early function of a new knee prosthesis with that of a standard implant. It demonstrates a small but significant clinical advantage for the mobile-bearing design.

Nine patients underwent arthrodesis of the knee using a customised coupled nail (the Mayday arthrodesis nail), five after infected arthroplasty, one following failed arthrodesis, one for intractable anterior knee pain, one for Charcot instability and one after trauma. Comparison was made with 17 arthrodeses, eight undertaken using external fixation, four with dual compression plates, and five with long Küntscher nails. Union was achieved in all patients (100%) at a mean time of ten months using the customised implant. There were no complications despite early weight-bearing. No further procedures were required. This contrasted with a rate of union of 53% and a complication rate of 76% with alternative techniques. Of this second group, 76% required a further operative procedure.

We compared the Mayday arthrodesis nail with other techniques of arthrodesis of the knee. The differences in the need for further surgery and occurrence of complications were statistically significant (p < 0.001), and differences in the rate of nonunion and inpatient stay of less than three weeks were also significant (p < 0.05) using Fisher’s exact test.

We conclude that a customised coupled intramedullary nail can give excellent stability allowing early weight-bearing, and results in a high rate of union with minimal postoperative complications.

As the surgical indications for total knee replacement (TKR) expand to include younger, heavier and more active patients, knowledge of the effect of these demographic variables on the outcome and survival of the implant is increasingly important.

Between November 1986 and September 1990, 402 patients underwent 562 primary cemented cruciate-retaining TKRs carried out by a single surgical team. The overall results showed a survival of 96.8% at 14 years with 1.44% lost to follow-up. Evaluating the demographics of these patients showed that certain groups fared significantly less well. The best results were seen in non-obese women with osteoarthritis who were over 60 years of age in whom there was ten-year survival of 99.4%. The worst results were in obese men with osteoarthritis who were less than 60 years of age in whom there was a ten-year survival of 35.7%. Caution should be exercised when considering TKR on a patient with this combination of poor risk factors.

By identifying demographic factors at the time of consultation the surgeon is better able to predict the survival of the TKR. This information is important when considering the best options for treatment of a patient and in providing accurate information during preoperative counselling.

We treated 13 patients who had a fixed valgus deformity of the knee with a semiconstrained total knee arthroplasty combined with advancement of the lateral collateral ligament by means of a lateral femoral condylar sliding osteotomy. At follow-up of between one and 6.5 years all patients were assessed using the Knee Society score. The mean knee score improved from 32 to 88 and the functional score from 45 to 73. The mean tibiofemoral angle was corrected from 191° to 180°. There was no postoperative tibiofemoral or patellar instability and, in most knees, distal transposition of the lateral femoral condyle achieved satisfactory stable alignment.

We describe 88 knees (79 patients) with lateral unicompartmental osteoarthritis which had been treated by the St Georg Sled prosthesis.

At a mean follow-up of nine years (2 to 21) 15 knees had revision surgery, nine for progression of arthritis, six for loosening, four for breakage of a component and four for more than one reason. Six patients complained of moderate or severe pain at the final follow-up. Only five knees were lost to follow-up in the 21-year period.

We performed survivorship analysis on the group using revision for any cause as the endpoint. At ten years the cumulative survival rate was 83%, and at 15 years, when ten knees were still at risk, it was 74%.

Based on our clinical results and survival rate the St Georg Sled may be considered to be a suitable unicompartmental replacement for isolated lateral compartment osteoarthritis.

Many knee surgeons flex the knee and sometimes also extend the hip before inflating a tourniquet on the thigh. This practice stems from the belief that these manoeuvres prevent excessive strain on the quadriceps during surgery, the assumption being that movement of the muscle is restricted by an inflated tourniquet. We therefore examined, using ultrasound, the movement of the quadriceps muscle above and below the tourniquet before and after inflation.

We applied a tourniquet of standard size to the thigh of five volunteers for approximately five minutes. A bubble of air was injected into the quadriceps muscle above the tourniquet and was the proximal point of reference. The musculotendinous junction was the distal point. The movement of the reference point was measured by ultrasound before and after inflation of the tourniquet. Each measurement was repeated with either the knee flexed and the hip extended, or the hip flexed and the knee extended. The mean and standard deviation were recorded.

Before inflation the mean amount of passive movement was 1.1 ± 0.13 cm proximal and 4.0 ± 0.08 cm distal to the tourniquet, with a range of movement of the knee of 0° to 137° (6.7°). After inflation the mean passive movement was 1.0 ± 0.07 cm proximal and 4.0 ± 0.08 cm distal to the tourniquet with a range of 0° to 132° (± 7.6°).

The ultrasound findings therefore have shown no evidence of restriction of the quadriceps muscle by an inflated tourniquet.

We undertook a prospective, randomised study of 135 total knee arthroplasties to determine the most accurate and reliable technique for alignment of the tibial prosthesis. Tibial resection was guided by either intramedullary or extramedullary alignment jigs.

Of the 135 knees, standardised postoperative radiographs suitable for assessment were available in 100. Correct tibial alignment was found in 85% of the intramedullary group compared with 65% of the extramedullary group (p = 0.019).

We conclude that intramedullary guides are superior to extramedullary instruments for alignment of the tibial prosthesis.

We examined an39 patients (45 knees) who had undergone Elmslie-Trillat procedure for recurrent or habitual dislocation of the patella with a follow-up of more than ten years. The mean age at the time of surgery was 18.4 years; the mean follow-up was 161 months (120 to 238). Using Fulkerson’s functional knee score, 41 knees (91%) had an excellent or good result at a mean follow-up of 45 months, and this was maintained in 29 (64%) at the final review.

The main cause of deterioration in the clinical results was the onset or worsening of patellofemoral joint pain, not patellar instability.

The meniscofemoral ligaments were studied in 84 fresh-frozen knees from 49 cadavers. Combined anterior and posterior approaches were used to identify the ligaments. In total, 78 specimens (93%) contained at least one meniscofemoral ligament. The anterior meniscofemoral ligament (aMFL) was present in 62 specimens (74%), and the posterior meniscofemoral ligament (pMFL) in 58 (69%). The 42 specimens (50%) in which both ligaments were present were from a significantly younger population than that with one MFL or none (p < 0.05). Several anatomical variations were identified, including oblique fibres of the posterior cruciate ligament (PCL), which were seen in 16 specimens (19%). These were termed the ‘false pMFL’.

The high incidence of MFLs and their anatomical variations should be borne in mind during arthroscopic and radiological examination of the PCL. It is important to recognise the oblique fibres of the PCL on MRI in order to avoid wrongly identifying them as either a pMFL or a tear of the lateral meniscus. The increased incidence of MFLs in younger donors suggests that they degenerate with age.

We have found poor mid-term results in a multisurgeon series of 94 Johnson-Elloy (Accord) total knee replacements. A total of 27 knees (29%) has required revision, in 26 for aseptic loosening. Only 18 (19%) remain in situ, and these give poor function, are painful and most show radiological evidence of early failure. At 12 to 13 years the survival rate is 43% (confidence interval 29 to 57) with failure requiring revision as the endpoint. Proximal migration of the femoral component is associated with considerable loss of bone stock. We believe that all patients who have this implant should be recalled for regular review in order to anticipate this problem.

When the Oxford unicompartmental meniscal bearing arthroplasty is used in the lateral compartment of the knee, 10% of the bearings dislocate. A radiological review was carried out to establish if dislocation was related to surgical technique.

The postoperative radiographs of 46 lateral unicompartmental arthroplasties were analysed. Five variables which related to the position and alignment of the components were measured. Dislocations occurred in six knees.

Only one of the five variables, the proximal tibial varus angle, had a statistically significant relationship to dislocation. This variable quantifies the height of the lateral joint line. The mean proximal tibial varus angle for knees the bearings of which had dislocated was 9° and for those which had not it was 5°. In both groups it was greater than would be expected in the normal knee (3°).

Our study suggests that a high proximal tibial varus angle is associated with dislocation. The surgical technique should be modified to account for this, with care being taken to avoid damage to or over-distraction of the lateral soft tissues.

We have carried out a long-term survival analysis of a prospective, randomised trail comparing cemented with cementless fixation of press-fit condylar primary total knee replacements. A consecutive series of 501 replacements received either cemented (219 patients, 277 implants) or cementless (177 patients, 224 implants) fixation.

The patients were contacted at a mean follow-up of 7.4 years (2.7 to 13.0) to establish the rate of survival of the implant. The ten-year survival was compared using life-table and Cox’s proportional hazard analysis.

No patient was lost to follow-up. The survival at ten years was 95.3% (95% CI 90.3 to 97.8) and 95.6% (95% CI 89.5 to 98.2) in the cemented and cementless groups, respectively. The hazard ratio for failure in cemented compared with cementless prostheses was 0.97 (95% CI 0.36 to 2.6). A comparison of the clinical outcome at ten years in 80 knees showed no difference between the two groups.

The survival of the press-fit condylar total knee replacement at ten years is good irrespective of the method of fixation and brings into question the use of more expensive cementless implants.

We have studied the long-term outcome of 408 primary medial St George Sled unicompartmental arthroplasties of the knee and 531 primary Kinematic total knee arthroplasties using survivorship analysis. The operations were performed by a number of surgeons under the supervision of two consultants at one orthopaedic centre. Prospective clinical assessment was carried out before and at 2, 5, 8, 10, 12 and 15 years after operation. Failure was defined as follows: revision or removal of the implant; the presence of moderate or severe pain; or ‘worst-case’ with all patients lost to follow-up.

Cumulative survival rates at ten years were calculated using life tables. The follow-up rate was 97%. At ten years, 25 medial sled arthroplasties and 20 Kinematic knee arthroplasties had been revised. With revision or removal as the survivorship endpoint at ten years there was a success rate of 87.5% for the medial sled and 89.6% for the Kinematic knee arthroplasty. When moderate or severe pain was included these rates became 79.4% for both arthroplasties. There was no statistically significant (p > 0.05) difference between the rates of survival for the two arthroplasties using either of the endpoint criteria.

Good or excellent results were recorded for 77.9% of the medial sled knees and 75.1% for the Kinematic knees. The former had 93.8% of cases with a final range of movement in excess of 90° compared with 83.7% for the Kinematic knees (p < 0.01). We conclude that at a single orthopaedic centre in the UK, the St Georg Sled medial compartment arthroplasty for appropriate specific indications offers predictable survivorship at ten years which is comparable with that of the Kinematic total knee arthroplasty.

We have evaluated prospectively the incidence and location of deep-vein thrombosis (DVT), the risk factors for pulmonary embolism, and the natural history of thrombosis after total knee replacement (TKR) in patients who did not receive prophylactic or therapeutic treatment for DVT.

We studied 227 patients who underwent primary TKR; 116 had one-stage bilateral and 111 unilateral procedures. Coagulation assays, the full blood count and blood typing tests for the serum chemical profile were undertaken in all patients on three separate occasions. Bilateral simultaneous or unilateral venograms were carried out at six or seven days after operation. Perfusion lung scanning was undertaken before and at seven or eight days after operation. Bilateral simultaneous or unilateral venograms were repeated six months after operation in all patients who had thrombi.

In the 116 patients with a bilateral replacement, 97 of 232 venograms (41.8%) were positive for fresh thrombi while there were 46 positive venograms (41.4%) in the 111 patients with a unilateral replacement (p = 1.000). Of the 116 venograms in knees with a cemented replacement, 45 (38.8%) were positive for thrombi while 52 of the 116 venograms (44.8%) were positive in those with a cementless replacement (p = 0.675). Further venograms at six months after operation in all 143 limbs which had thrombi showed that all had completely resolved regardless of the size or location. No pulmonary embolism occurred as shown by negative perfusion lung scans and the absence of symptoms.

Although the current prevailing opinion is that patients with thrombosis in the proximal veins should receive anticoagulant treatment, our study has shown that all thrombi regardless of their size or location resolved without causing pulmonary embolism.

We investigated the clinical, arthroscopic and biomechanical outcome of transplanting autologous chondrocytes, cultured in atelocollagen gel, for the treatment of full-thickness defects of cartilage in 28 knees (26 patients) over a minimum period of 25 months. Transplantation eliminated locking of the knee and reduced pain and swelling in all patients. The mean Lysholm score improved significantly. Arthroscopic assessment indicated that 26 knees (93%) had a good or excellent outcome. There were few adverse features, except for marked hypertrophy of the graft in three knees, partial detachment of the periosteum in three and partial ossification of the graft in one. Biomechanical tests revealed that the transplants had acquired a hardness similar to that of the surrounding cartilage. We conclude that transplanting chondrocytes in a newly-formed matrix of atelocollagen gel can promote restoration of the articular cartilage of the knee.

The Bisurface knee prosthesis (BP) has a posterior stabilising cam (ball-and-socket joint) in the mid-posterior region of the femorotibial joint in an attempt to improve the range of movement. Based on an in vitro weight-bearing study contact areas of the Insall/Burstein 2 (IB2) and the BP knee were compared using pressure-sensitive films. The stability afforded by the cam was evaluated by means of dislocation distances in the vertical and horizontal planes.

Significant adverse anterior translation in mid-flexion was not observed with the BP knee since the cam was effective above 60° of flexion. At flexion of 60° or more, the total contact areas were larger, as the cam represented a weight-bearing surface. The dislocation distances for the BP knee compared favourably with those for the IB2 knee. We conclude that the cam of the BP knee allows good movement, stability and wear.

We have undertaken a randomized clinical trial comparing two methods of reconstruction of the anterior cruciate ligament in patients with chronic instability. We used an ipsilateral bone-patellar-tendon-bone autograft in 27 patients and the Ligament Advancement Reinforcement System (LARS) artificial ligament in 26. Assessment before and at two, six, 12 and 24 months after surgery, included the history, physical examination, a modified International Knee Documentation Committee (IKDC) score, the Tegner score, the Knee Injury and Osteoarthritis Outcome Score (KOOS) and instrumented laxity testing.

There were no cases of reactive synovitis or of infection of the knee, and there was no difference regarding the failure rate between the two groups. The IKDC showed no significant differences between the two groups at any stage of the follow-up. The KOOS evaluation showed consistently better results in all subscales for the LARS group during the first year of follow-up. After 24 months these differences were no longer evident. Instrument-tested laxity was greater in the LARS group at all stages of follow-up, but the differences were not significant at 24 months.

Our findings suggest that at follow-up at 24 months the LARS ligament seems to be a satisfactory treatment option, especially when an early return to high levels of activity is demanded.

Many authors have recommended undercorrection of the deformity when carrying out unicompartmental knee arthroplasty (UKA). The isolated effect of alignment of the knee on the outcome of UKA has, however, received little attention.

We reviewed 185 UKAs at a minimum of five years after surgery. They had been carried out by a single surgeon using metal-backed tibial components in the management of arthritis of the medial compartment. We measured the tibiofemoral angle (TFA) before and at four months after operation and at the most recent assessment. The amount of correction of the TFA and any subsequent loss were recorded.

While adjusting for the effects of age, weight and gender of the patients and the type and thickness of the implants, the mean correction was significantly less for those with a Marmor rating of failure (6.8°) than for those rated excellent (9.2°). The mean correction was also significantly less for patients with a Marmor rating of failure (6.8°) than for those rated poor (11.1°). The mean correction for the UKAs which were revised (6.6°) was significantly less than for those not revised (9.1°). Additionally, revised UKAs had a significantly higher percentage (63%) of thinner tibial implants (< 8 mm) than the surviving UKAs (27%). These findings suggest that undercorrection of the TFA in UKA of the medial compartment should be avoided, particularly if a thin tibial polyethylene insert is used.

Patients who undergo total knee replacement (TKR)are at high risk of venous thromboembolism. Low-molecular-weight heparins (LMWH) are the most suitable chemical prophylactic agents but there are some uncertainties about their safety and effectiveness. The foot pump offers an alternative.

We randomised 229 patients undergoing primary, unilateral TKR to receive either the A-V Impulse foot pump or enoxaparin, a LMWH. Ascending venography was undertaken between the sixth and eighth postoperative day in 188 patients without knowledge of the randomisation category. The prevalence of venographic deep-vein thrombosis was 58% (57/99) in the foot-pump group and 54% (48/89) in the LMWH group which was not statistically significant. There were four cases of proximal thrombi and two of fatal pulmonary emboli in the foot-pump group and none in the LMWH group. There were fewer haemorrhagic complications and soft-tissue effects in the foot-pump group.

We conclude that the neither method provides superior prophylaxis.

We have analysed retrospectively the relationship between the axial parameters of alignment of the lower limb and the recurrence of varus deformity after high tibial osteotomy. We studied 29 patients (37 knees) with a mean age at surgery of 66 years. The mean follow-up was for 7.4 years (5 to 10.5). Recurrence of varus deformity was defined as an increase in the femorotibial angle of 3° or more, compared with that obtained six months after the operation. There were four patients (four knees) with recurrence of varus deformity. They had a greater varus inclination of the distal femur than those without varus recurrence.

An association between varus inclination of the distal femur and horizontal obliquity of the joint surface was observed. Excessive obliquity prevents the shift of weight-bearing to the lateral compartment, and may cause a recurrence of varus deformity after high tibial osteotomy.

We describe a prospective survival analysis of 63 consecutive meniscal allografts transplanted into 57 patients. The lateral meniscus was transplanted in 34, the medial meniscus in 17, and both menisci (combined) in the same knee in six. For survival analysis we used persistent pain or mechanical damage as clinical criteria of failure. A total of 13 allografts failed (5 lateral, 7 medial, 1 medial and lateral).

A significant negative correlation (p = 0.003) was found between rupture of the anterior cruciate ligament (ACL) and successful meniscal transplantation. A significant difference (p = 0.004) in the clinical results was found between lateral and medial meniscal transplants.

The cumulative survival rate of the lateral, medial and combined allografts in the same knee, based on the life-table method and the Kaplan-Meier calculation, was 76%, 50% and 67%, respectively. The survival of medial meniscal allografts may improve when reconstruction of the ACL is carried out at the same time as meniscal transplantation in an ACL-deficient knee.

We describe the results of total knee arthroplasty (TKA) undertaken for severe, neurosyphilitic Charcot arthropathy in ten patients (19 knees). A cemented condylar, constrained prosthesis was implanted in all but two knees. The mean follow-up was 5.2 years (5 to 6). The mean knee score before operation was 36.5 points (30 to 42) which improved to 76 points (58 to 90) after operation as judged by the Hospital for Special Surgery score. At final follow-up three knees (16%) had aseptic loosening which required salvage by an arthrodesis, six (31%) were functioning poorly and ten (53%) were satisfactory.

We conclude that although Charcot arthropathy is not an absolute contraindication to total knee replacement, there is a high incidence of serious complications.

We have investigated the ability to kneel after total knee replacement. We asked 75 patients (100 knees) at least six months after routine uncemented primary total knee replacement, to comment on and to demonstrate their ability to kneel. Differences between the perceived and actual ability to kneel were noted. In 32 knees patients stated that they could kneel without significant discomfort. In 54 knees patients avoided kneeling because of uncertainties or recommendations from third parties (doctors, nursing staff, friends, etc). A total of 64 patients was actually able to kneel without discomfort or with mild discomfort only and 12 of the remainder were unable to kneel because of problems which were not related to the knee. Twenty-four patients therefore were unable to kneel because of discomfort in the knee.

There was no difference between the ‘kneelers’ and ‘non-kneelers’ with regard to overall knee score, range of movement and the presence of patellar resurfacing.

We studied 19 videotaped knee arthroscopies in 19 patients with mild to moderate osteoarthritis (OA) of the knee in order to compare the intraobserver and interobserver reliability and the patterns of disagreement between four orthopaedic surgeons. The classifications of OA of Collins, Outerbridge and the French Society of Arthroscopy were used. Intraobserver and interobserver agreements using kappa measures were 0.42 to 0.66 and 0.43 to 0.49, respectively. Only 6% to 8% of paired intraobserver classifications differed by more than one category. Observer-specific disagreement was evident both within and between observers. A small, but significant, occasional variation was also seen. Although reliability may improve by an analysis of disagreement, it appears that the arthroscopic grading of early osteoarthritic lesions is inexact.

A total of 60 children and adolescents with rupture of the anterior cruciate ligament (ACL) was seen between 1980 and 1990. Observation of the 23 patients who were treated conservatively revealed that the natural history of the injury resulted in severe instability and poor function of the knee. Associated meniscal tears were present in 15 knees. Three osteochondral fractures occurred and osteoarthritic changes developed in ten knees.

In 1990 therefore we introduced reconstruction of the ACL with a four-strand hamstring graft using an anatomical placement with transphyseal tunnels and anchorage well away from the growth plate. Over a period of nine years, 47 knees underwent reconstruction. The mean follow-up was 49 months (12 to 96). No child suffered physeal damage or leg-length discrepancy. The results were satisfactory in 77% and there was little difference between patients treated before the adolescent growth spurt and those treated during or after this time. These results, however, were not as good as those seen in adults during the same period.

We undertook 114 arthroscopic meniscal repairs in 111 patients and subsequently carried out second-look arthroscopy to confirm meniscal healing at a mean of 13 months after repair. Stable healing at the repaired site was seen in 90. Of these, however, 13 had another arthroscopy later for a further tear. The mean period between the repair and the observation of a repeat tear was 48 months. Of the 13 patients, 11 had returned to high activity levels (International Knee Documentation Committee level I or II) after the repair.

An attempt should be made to preserve meniscal function by repairing tears, but even after arthroscopic confirmation of stable healing repaired menisci may tear again. The long-term rate of healing may not be as high as is currently reported. Second-look arthroscopy cannot predict late meniscal failure and may not be justified as a method of assessment for meniscal healing. Young patients engaged in arduous sporting activities should be reviewed regularly even after arthroscopic confirmation of healing.

We carried out a prospective study in order to establish to what extent the intra-articular evaluation undertaken during arthroscopy of the knee differed between surgeons. Two senior specialist registrars and a consultant orthopaedic surgeon with a special interest in knee surgery were involved. A total of 78 knee arthroscopies (78 patients) was studied. Arthroscopy was first carried out by the trainee and then by the senior author (ACWH). The intra-articular evaluation during the arthroscopy was recorded independently by a third person in the operating theatre. Data were collected to record variations in examination under anaesthesia, the morphology and pathology of the menisci and anterior cruciate ligament and the state of the articular surfaces.

The overall interobserver variation was 20% in all categories. We question the published results of intra-articular evaluation during knee arthroscopy when surgeons of different levels of experience are involved in a single study.

Our purpose was to determine the mechanism which allows the maximum knee flexion in vivo after a posterior-cruciate-ligament (PCL)-retaining total knee arthroplasty.

Using three-dimensional computer-aided design videofluoroscopy of deep squatting in 29 patients, we determined that in 72% of knees, direct impingement of the tibial insert posteriorly against the back of the femur was the factor responsible for blocking further flexion.

In view of this finding we defined a new parameter termed the ‘posterior condylar offset’. In 150 consecutive arthroplasties of the knee, the magnitude of posterior condylar offset was found to correlate with the final range of flexion.

Ulceration of the lower leg is considered to be a ‘hard’ clinical endpoint of venous thrombosis. Total knee replacement (TKR) is a significant risk factor for venous thrombosis of the leg and therefore potentially for ulceration.

We sent a postal questionnaire to 244 patients at a minimum of five years after TKR enquiring about the development of ulceration since their TKR. The overall incidence of ulceration, both active and healed, was 8.67% which is similar to that in the age-matched general population (9.6% to 12.6%), as was the prevalence of active ulceration. We also identified no clear association between venographically-confirmed postoperative deep-venous thrombosis (DVT) and the incidence and prevalence of ulcers at five years. We suggest that after TKR DVT is not a significant risk factor for ulceration of the leg and that perioperative chemical thromboprophylaxis may not be justified on these grounds.

We have assessed the effectiveness of reconstruction of the anterior cruciate ligament (ACL) in reducing functional tibial translation (TT).

The gait of 11 ACL-deficient patients was studied using Vicon equipment before and after surgery. Measurements of the angle between the patellar tendon and the long axis of the tibia were obtained in order to calculate TT in the sagittal plane relative to the uninjured limb during standing and walking.

Before surgery, patients did not show abnormal TT on the injured side, but after surgery significant anterior TT was found in the operated limb for every parameter of gait.

Abnormal anterior TT occurring during activity does not seem to be reduced by reconstruction; rather, it increases. It may be that the increased translation results from relaxation of excess contraction of the hamstring muscles, since compensatory muscle activity no longer is required in a reconstructed knee. The reduction of TT may not be an appropriate objective in surgery on the ACL.

The loss of full muscle activation contributes to weakness of the quadriceps muscle in patients with deficiency of the anterior cruciate ligament (ACL). We examined whether a deficit of voluntary activation (VA) of the quadriceps muscle can be reversed by reconstruction of the ACL and assessed its influence on muscle strength and clinical parameters.

We evaluated 12 male subjects with an isolated tear of the ACL and 12 matched control subjects before operation and two years after reconstruction of the ACL. Assessment included measurements of isometric knee-extension torque at maximal voluntary contraction (MVC force), knee stability tests, the International Knee Ligament Standard Evaluation Form and the Tegner activity score. A sensitive method of twitch interpolation was used to quantify the VA and to calculate true muscle force.

Before operation we found a deficit of VA on both the injured (mean ±SEM 74.9 ± 3.5%) and the uninjured side (74.6 ± 3.0%) in comparison with the control group (91 ± 0.9%). Two years after reconstruction of the ACL the VA improved significantly on both sides but remained less than that of the controls. Correlation analysis revealed an improvement of the VA in patients who returned to a higher level of activity. The deficit of true muscle force, however, persisted regardless of the clinical outcome and ligament stability.

Conventional high tibial osteotomy for osteoarthritis of the medial compartment of the knee with closed-wedge or dome osteotomy (DMO) may produce shortening of the patellar tendon and loss of inclination of the proximal tibial plateau or of the offset of the tibial condyle relative to its bony axis. This can make subsequent total knee arthroplasty technically demanding.

We undertook a prospective study comparing these changes after DMO with those after using open-wedge osteotomy hemicallotasis (HCO). A total of 50 knees with arthritis of the medial compartment in 46 consecutive patients was randomly allocated to either DMO or HCO. There were no significant differences between the groups with regard to age, gender, femorotibial angle before operation or the angle of correction.

Radiological studies showed that HCO caused little change in the length of the patellar tendon or the inclination angle of the tibial plateau, while after DMO both gradually decreased. The degree of tibial condylar offset increased in both groups, but less so in the HCO group.

A total of 30 patients who underwent endoscopic reconstruction of the anterior cruciate ligament using quadrupled hamstring tendons, through a single drill hole in the femur, had MRI 24 to 28 months after operation. In 18 patients the scans revealed that both the anterior and posterior portions of the graft ran in parallel from the inside of the femoral to the tibial tunnel. In 12, the posterior bundle had moved anteriorly and the anterior bundle could not be identified at the anterodistal border of the femoral tunnel. The mean difference in the anterior laxity, when compared with the contralateral knee, was 2.0 ± 1.7 mm and 4.3 ± 2.8 mm for the two types, respectively. Damage to the anterior bundle may occur when using the endoscopic technique because of biomechanical disadvantages, including concentration of loading and repetitive bending stress in the anterior bundle at the opening of the femoral tunnel.

The Fulkerson osteotomy has proved to be a reliable treatment for subluxation of the patella due to malalignment. Aggressive rehabilitation in the early postoperative period is unwise since the proximal tibia is weakened by the oblique osteotomy. Early weight-bearing and unrestricted activity have caused fractures in a few patients. Even late in the postoperative period the osteotomy may adversely influence the biomechanical properties of the proximal tibia.

We describe two athletes who sustained a fracture of the proximal tibia, during recreational activities, six months after a Fulkerson osteotomy. Both had been bearing full weight for about ten weeks without complaint. Bony healing of the osteotomy had been demonstrated on plain radiographs at ten and at 12 weeks. After a Fulkerson osteotomy, jogging and activities which impose considerable impact force should be discouraged for at least nine to 12 months.

Tibiofemoral alignment has a direct correlation with the survival of total knee arthroplasty. Traditionally, it has been measured using a goniometer on radiographs. We describe new software which measures this alignment on scanned radiographs by automatically detecting bones in the image.

Two surgeons used conventional methods and two clerical officers used the computerised routine to assess 58 radiographs of the knee on two occasions. There were no significant differences between any of the paired comparisons. The largest mean difference detected was 1.19°. Across all comparisons, the mean correlation was 0.755. A standardised routine for measuring tibiofemoral alignment was the greatest factor in reducing error in our study.

These results show that non-medical staff can reliably use the software to measure tibiofemoral alignment. It has the potential to measure all the parameters recommended by the Knee Society.

We studied the quality of fixation of the tibial component using radiostereometric analysis (RSA) in 40 patients who had undergone a cemented Freeman-Samuelson total knee arthroplasty. They were prospectively randomised to either a stemmed metal-backed (MB) or non-stemmed all-polyethylene (AP) tibial component. The articulating geometry of the implants was identical, as was the operative technique and the postoperative regime.

The study showed no complications of fixation using AP tibial components, and the migration was the same as that of their metal-backed counterparts. There was no bony collapse or increased subsidence of any part of the tibial component or increased incidence of radiolucent lines in the knees with AP components. Most AP implants were stable between one and two years after surgery, a finding known to be of positive prognostic significance when predicting future aseptic loosening.

We present a prospective review of the outcome of 76 Lubinus patellofemoral arthroplasties carried out in 59 patients between 1989 and 1995. At a mean follow-up of 7.5 years, 62 knees in the 48 patients were reviewed; 11 patients (14 knees) had died. None was lost to follow-up.

The clinical outcome using the Bristol Knee Scoring system was satisfactory in 45% of the cases. Maltracking of the patella, resulting in lateral tilt, subluxation and polyethylene wear, was the most common complication (32%). Revision surgery was carried out in 21 knees (28%) giving a cumulative survival rate of 65% (confidence interval (CI) 49 to 77) at eight years. The survival rate for revision and moderate pain was 48% (CI 36 to 59) at six years. Progression of arthritis was seen in seven cases (9%). In five of these (6.5%), the symptoms were severe enough to need revision surgery. Due to the high proportion of unsatisfactory results, we have discontinued the use of this prosthesis.

We studied 99 patients who were undergoing total knee arthroplasty (TKA) to determine the optimum protocol for the administration of tranexamic acid (TNA) in order to reduce blood loss. It decreased by more than 40% after the administration of TNA. The haemostatic effect was greatest when TNA was given preoperatively and on deflation of the tourniquet. There was no increase in the incidence of adverse affects in the patients receiving TNA, compared with a control group.

We conclude that two injections of TNA, one given preoperatively and one on deflation of the tourniquet, significantly reduce blood loss without increasing the risk of thromboembolic complications.

We have performed a prospective single-blinded randomised study to evaluate the role of antibiotic-impregnated cement in the prevention of deep infection at primary total knee arthroplasty (TKA) in patients with diabetes mellitus. We studied prospectively 78 arthroplasties performed for osteoarthritis in such patients. They were randomly separated into two groups. In group 1 (41 knees), cefuroxime-impregnated cement was used while in group 2 (37 knees) cefuroxime was not added to the cement. The preoperative, intraoperative and postoperative management was the same for both groups. The mean follow-up was 50 months (26 to 88).

There were no cases of deep infection in group 1, but five (13.5%) occurred in group 2 (p = 0.021). We conclude that cefuroxime-impregnated cement is effective in the prevention of deep infection at primary TKA in patients with diabetes mellitus.

We evaluated the outcome of partial lateral meniscectomy of 31 knees in 29 patients whose knees were otherwise normal. The mean follow-up was 10.3 years.

According to the Lysholm score, 14 knees were rated as excellent, four as good, five as fair and eight as poor, with a mean score of 80.5 points. Radiologically, only one lateral compartment was classified as grade 0, eight as grade 1, nine as grade 2, 11 as grade 3, and two as grade 4 according to Tapper and Hoover. No significant (p < 0.05) correlation was found between the amount of tissue resected and the subjective, clinical and radiological outcome.

Although early results of lateral meniscectomy may be satisfactory, we have demonstrated that in the long term there was a high incidence of degenerative changes, a high rate of reoperation (29%) and a relatively low functional outcome score.

We analysed the long-term results with a mean follow-up of 10.2 years, of 66 total knee replacements in 42 patients with rheumatoid arthritis. In all cases the posterior cruciate ligament was retained.

There were only three complications (4.5%). Revision surgery was necessary in five knees (7.6%), including one (1.5%) with infection. At the final follow-up, 75.8% of knees were rated excellent clinically. Only 15% had an excellent function score. The survival rate of the implant was 90.7% at 19 years.

The clinical, radiological and survivorship analysis shows that the posterior-cruciate-retaining knee arthroplasty performs well in rheumatoid arthritis.

We present the long-term results of the Kinematic Condylar Knee Arthroplasty followed in a prospective fashion. Between October 1982 and March 1988, 404 consecutive replacement arthroplasties were carried out on 335 patients. Of these, 354 knees had osteoarthritis, 45 rheumatoid arthritis and five other diagnoses. At the time of final follow-up 158 patients (188 knees) had died. No patient was lost to follow-up. The minimum follow-up for all living patients was ten years (10 to 17). The mean age at surgery was 68 years (30 to 92). There were seven complications (1.7%). Sixteen knees (3.9%) were revised, four because of infection. Survivorship was 99.4% (CI 97.9 to 99.8) at five years, 98.2% (CI 96.1 to 99.2) at ten years and 92.6% (CI 87.6 to 95.6) at 17 years.

In a two-centre study, 164 patients with unilateral instability of the anterior cruciate ligament were prospectively randomised to arthroscopic reconstruction with either a patellar tendon graft using interference screw fixation or a quadruple semitendinosus graft using an endobutton fixation technique. The same postoperative rehabilitation protocol was used for all patients and follow-up at a median of 31 months (24 to 59) was carried out by independent observers. Four patients (2%) were lost to follow-up.

No significant differences were found between the groups regarding the Stryker laxity test, one-leg hop test, Tegner activity level, Lysholm score, patellofemoral pain score, International Knee Documentation Committee (IKDC) score or visual analogue scale, reflecting patient satisfaction and knee function. Slightly decreased extension, compared with the non-operated side, was found in the patellar tendon group (p < 0.05). Patients with associated meniscal injuries had lower IKDC, visual analogue (p < 0.01) and Lysholm scores (p < 0.05) than those without such injuries. Patients in whom reconstruction had been carried out less than five months after the injury had better final IKDC scores than the more chronic cases (p < 0.05).

We conclude that patellar tendon and quadruple semitendinous tendon grafts have similar outcomes in the medium term. Associated meniscal pathology significantly affects the final outcome and early reconstruction seems to be beneficial.

We reviewed the outcome of 422 primary cemented Kinemax total knee arthroplasties implanted into 369 patients over a period of five years, from January 1989. The operations were carried out at two NHS district general hospitals and one teaching hospital by 31 surgeons. During the period of review, 49 patients died and ten knees were lost to follow-up (68 knees). The mean Knee Society score improved from 28 before to 89 after surgery, and the mean function score increased from 23 to 79. The range of flexion improved from 92° to 105°.

These improvements were maintained throughout the period of study. At the latest review radiolucent lines of 1 mm were seen around 15% of tibial components, 1.4% of patellar components and 9.5% of femoral components. In no case were these changes progressive. Using revision as the endpoint, cumulative survival was 99% after five years and 96.95% after nine years. All revisions were undertaken for deep infection or secondary trauma.

Our study has shown that the Kinemax total knee replacement, when carried out with retention of the posterior cruciate ligament by surgeons of varying experience, produces very satisfactory results in the medium term.

The Swedish Knee Arthroplasty Registry (SKAR) has recorded knee arthroplasties prospectively in Sweden since 1975. The only outcome measure available to date has been revision status. While questionnaires on health outcome may function as more comprehensive endpoints, it is unclear which are the most appropriate. We tested various outcome questionnaires in order to determine which is the best for patients who have had knee arthroplasty as applied in a cross-sectional, discriminative, postal survey.

Four general health questionnaires (NHP, SF-12, SF-36 and SIP) and three disease/site-specific questionnaires (Lequesne, Oxford-12, and WOMAC) were tested on 3600 patients randomly selected from the SKAR. Differences were found between questionnaires in response rate, time required for completion, the need for assistance, the efficiency of completion, the validity of the content and the reliability. The mean overall ranks for each questionnaire were generated. The SF-12 ranked the best for the general health, and the Oxford-12 for the disease/site-specific questionnaires. These two questionnaires could therefore be recommended as the most appropriate for use with a large knee arthroplasty database in a cross-sectional population.

There is a need for the accurate measurement of the outcome after knee surgery. The Oxford Knee Score is being increasingly used since it is reported to be short, simple, inexpensive and validated.

We sent the questionnaire to 346 patients awaiting surgery to the hip or lumbar spine. Only 11% of 141 patients with proximal pathology who denied knee problems gave a maximum score. Their mean score was substantially lower than expected at 28.7 (maximum 48), and was significantly lower than the score of 36.5 obtained from patients after total knee replacement.

We therefore suggest that the frequent coexistence of hip or spinal pathology will significantly alter both the absolute score and any improvement to be expected after knee surgery. Although sensitive to disability originating from the knee the Oxford Knee Score is not sufficiently specific since it is heavily influenced by more proximal pathology.

We describe a method of audit of a type of total knee replacement, including some details of the organisational difficulties of administering multicentre studies, and draw attention to how this can be done using industrial funding without prejudicing the study. This is a prospective record of 1439 patients who had an Insall-Burstein II (IBII) prosthesis implanted between 1990 and 1994. The data were collected using the American Knee Society scoring system. A method of storing radiographs digitally at low cost is also described.

The results emphasise the need for the long-term collection of data on commonly used devices implanted by a cross-section of surgeons. We conclude that for most patients the IBII cemented, posteriorly stabilised, cruciate-substituting prosthesis will relieve pain and give excellent functional results throughout the patients’ remaining years with a very small incidence of revision, except in cases of infection.

We describe the outcome of a series of 124 Oxford meniscal-bearing unicompartmental arthroplasties carried out for osteoarthritis of the medial compartment. They had been undertaken more than ten years ago in a non-teaching hospital in Sweden by three surgeons. All the knees had an intact anterior cruciate ligament, a correctable varus deformity and full-thickness cartilage in the lateral compartment. Thirty-seven patients had died; the mean time since operation for the remainder was 12.5 years (10.1 to 15.6).

Using the endpoint of revision for any cause, the outcome for every knee was established. Six had been revised (4.8%). At ten years there were 94 knees still at risk and the cumulative survival rate was 95.0% (95% confidence interval 90.8 to 99.3). This figure is similar to that reported by the designers of the prosthesis and to the best published results for independent series of total knee replacement. If patients are selected appropriately, this implant is a reliable treatment for anteromedial osteoarthritis of the knee.

We used electrogoniometers to measure the range of movement (ROM) of the knee during various activities, comparing 50 patients with osteoarthritis of the knee (OA) with 20 healthy age- and sex-matched subjects.

The minimum and maximum joint angles and the ranges of excursion of the patient and control groups were tested for significant differences, using an unrelated Student’s t-test with pooled variance. Knee flexion in patients with OA was significantly reduced during all activities (p < 0.05), but differences in knee extension were not significant except when patients negotiated stairs. We believe that this reduction in ROM is caused by inhibition due to pain when load-bearing. Static non-load-bearing measurements of the ROM poorly reflected the functional ROM, with a coefficient of determination (r²) of 0.59 in the patient group and 0.60 in the control group. Electrogoniometry of the ROM of the knee provides a reliable, accurate and objective measurement of knee function.

We treated 15 patients by arthrodesis of the knee after removal of an infected total knee arthroplasty, using an Ilizarov ring fixator. Eight had a failed arthrodesis by another technique. The mean age of the patients was 75 years, the mean duration of retention of the frame was 28 weeks, the mean treatment time 51 weeks, and the mean follow-up 52 months. All but one knee fused at the first attempt, a rate of union of 93%. The incidence of complications related to treatment was 80%. The length of treatment and rates of complication were attributed to advanced age and the adverse local clinical factors in these patients. The Ilizarov method is a promising technique for achieving arthrodesis under these circumstances.

A total of 10474 unicompartmental knee arthroplasties was performed for medial osteoarthritis in Sweden between 1986 and 1995. We sought to establish whether the number of operations performed in an orthopaedic unit affected the incidence of revision. Three different implants were analysed: one with a high revision rate, known to have unfavourable mechanical and design properties; a prosthesis which is technically demanding with a known increased rate of revision; and the most commonly used unicompartmental device.

Most of the units performed relatively few unicompartmental knee arthroplasties per year and there was an association between the mean number carried out and the risk of later revision. The effect of the mean number of operations per year on the risk of revision varied. The technically demanding implant was most affected, that most commonly used less so, and the outcome of the unfavourable design was not influenced by the number of operations performed.

For unicompartmental arthroplasty, the long-term results are related to the number performed by the unit, probably expressing the standards of management in selecting the patients and performing the operation.

We reviewed 74 partial medial meniscectomies in 57 patients with stable knees, to assess the long-term functional and radiological outcome. The International Knee Documentation Committee score and the residual laxity were assessed in both knees. At the time of surgery the mean age of the patients was 36 ± 11 years and the mean follow-up was 12 ± 1 years. All had a limited medial meniscectomy. The anterior cruciate ligament was intact in all cases. The meniscal tear was vertical in 95% and complex in 5%. The posterior part of the meniscus was removed in 99%. A peripheral rim was preserved in all cases. After 12 years 95% of the patients were satisfied or very satisfied with their knee(s). Objectively, 57% had grade A function and 43% were grade B. The outcome correlated only with the presence of anterior knee pain at final follow-up. In the 49 cases of arthroscopic meniscectomy for which there was a contralateral normal knee there was narrowing of the ‘joint-space’ in 16% of the operated knees. There was no correlation between this and other parameters such as age or different meniscal pathologies.

We have investigated whether the thigh tourniquet used during total knee replacement (TKR) influenced the development of postoperative wound hypoxia and was a cause of delayed wound healing.

We allocated randomly 31 patients (31 TKRs) to one of three groups: 1) no tourniquet; 2) tourniquet inflated at low pressure (about 225 mmHg); and 3) tourniquet inflated to high pressure of about 350 mmHg. Wound oxygenation was measured using transcutaneous oxygen electrodes.

In the first week after surgery, patients with a tourniquet inflated to a high pressure had greater wound hypoxia than those with a low pressure. Those without a tourniquet also had wound hypoxia, but the degree and duration were less pronounced than in either of the groups with a tourniquet.

Use of a tourniquet during TKR can increase postoperative wound hypoxia, especially when inflated to high pressures. Our findings may be relevant to wound healing and the development of wound infection.

We carried out weight-bearing video radiological studies on 40 patients with a total knee arthroplasty (TKA), to determine the presence and magnitude of femoral condylar lift-off. Half (20) had posterior-cruciate-retaining (PCR) and half (20) posterior-cruciate-substituting (PS) prostheses. The selected patients had successful arthroplasties with no pain or instability. Each carried out successive weight-bearing knee bends to maximum flexion, and the radiological video tapes were analysed using an interactive model-fitting technique.

Femoral lift-off was seen at some increment of knee flexion in 75% of patients (PCR TKA 70%; PS TKA 80%). The mean values for lift-off were 1.2 mm with a PCR TKA and 1.4 mm with a PS TKA. Lift-off occurred mostly laterally with the PCR TKA, and both medially and laterally with the PS TKA. Separation between the femoral condyles and the articular surface of the tibia was recorded at 0°, 30°, 60° and 90° of flexion. Femoral condylar lift-off may contribute to eccentric polyethylene wear, particularly in designs of TKA which have flatter condyles. Coronal conformity is an important consideration in the design of a TKA.

Anterior knee pain due to dysplasia of the extensor mechanism is common. We have studied 137 knees (103 patients) in order to identify a rapid and reproducible radiological feature which would indicate the need for further analysis.

Overall, 67 knees (49%) had at least one radiological abnormality; 70 (51%) were considered normal. There were five cases of Dejour type-3 dysplasia of the femoral trochlea, nine of type-2 and 12 of type-1. There were 49 cases of patella alta and five of patella infera. Four knees had an abnormal lateral patellofemoral angle (patellar tilt), and in 15 knees there was more than one abnormality. Classification of trochlear dysplasia was difficult and showed poor reproducibility. This was also true for the measurement of the lateral patellofemoral angle. Patellar height was more easily measured but took time. The sulcus angle is an easily and rapidly measurable feature which was reproducible and was closely related to other features of dysplasia of the extensor mechanism.

The finding of a normal sulcus angle suggested that seeking other radiological evidence of malalignment of the extensor mechanism was unlikely to reveal additional useful information. The severity of other features of dysplasia of the extensor mechanism correlated with increasing sulcus angle.

We have sought to clarify whether the traditional Arabic lifestyle prevents restriction of movement in patients with degenerative arthritis of the knee. The range of movement of 68 osteoarthritic knees of Arabic patients was compared with that of 51 healthy knees of Muslim patients and 83 osteoarthritic knees in non-Arabic patients.

The range of flexion of the osteoarthritic knees in the Arabic patients matched that of the healthy control knees, but was significantly better than that of the osteoarthritic knees in the non-Arabic patients. There was also a statistically significant difference between the mean extension deficit of the two groups with osteoarthritis. Exercises may help to prevent restriction of movement in osteoarthritis of the knee.

The use of a valgus brace can effectively relieve the symptoms of unicompartmental osteoarthritis of the knee. This study provides an objective measurement of function by analysis of gait symmetry. This was measured in 30 patients on four separate occasions: immediately before and after initial fitting and then again at three months with the brace on and off. All patients reported immediate symptomatic improvement with less pain on walking. After fitting the brace, symmetry indices of stance and the swing phase of gait showed a consistent and immediate improvement at 0 and 3 months, respectively, of 3.92% (p = 0.030) and 3.40% (p = 0.025) in the stance phase and 11.78% (p = 0.020) and 9.58% (p = 0.005) in the swing phase. This was confirmed by a significant improvement at three months in the mean Hospital for Special Surgery (HSS) knee score from 69.9 to 82.0 (p < 0.001). Thus, wearing a valgus brace gives a significant and immediate improvement in the function of patients with unicompartmental osteoarthritis of the knee, as measured by analysis of gait symmetry.

A total of 90 patients with an isolated rupture of the anterior cruciate ligament (ACL) had a reconstruction using the ipsilateral patellar tendon secured with round-headed cannulated interference screws. Annual review for five years showed three failures of the graft (two traumatic and one atraumatic); none occurred after two years. Ten patients sustained a rupture of the contralateral ACL. At five years, 69% of those with surviving grafts continued to participate in moderate to strenuous activity. Using the International Knee Documentation Committee assessment, 90% reported their knee as being normal or nearly normal and had a median Lysholm knee score of 96 (64 to 100). Most patients (98%) had a pivot shift of grade 0 with the remaining 2% being grade 1; 90% of the group had a Lachman test of grade 0. The incidence of subsequent meniscectomy was similar in the reconstructed joint to that in the contralateral knee. Radiological examination was normal in 63 of 65 patients. Our study supports the view that reconstruction of the ACL is a reliable technique allowing full rehabilitation of the previously injured knee. In the presence of normal menisci there is a low incidence of osteoarthritic change despite continued participation in sporting activity.

Between March 1987 and March 1997, we performed a modified Thompson quadricepsplasty on 20 stiff knees and followed the patients for a mean of 35 months (24 to 52). After the operation, the knee was immobilised in flexion and periodically extended. At the final follow-up, the mean active flexion was 113.5° (75 to 150). The final mean gain in movement was 67.6° (5 to 105). One patient had a deep infection which resolved after wound care and intravenous antibiotics. The modified Thompson quadricepsplasty with appropriate postoperative care can give good results.

Failure of a unicompartmental knee replacement (UKR) may be caused by progressive osteoarthritis of the knee and/or failure of the prosthesis. Limb alignment can influence both of these factors. We have examined the fate of the other compartments and measured changes in leg alignment after UKR.

A total of 50 UKRs was carried out on 45 carefully selected patients between 1989 and 1992. At operation, deliberate attempts were made to avoid overcorrection of the deformity. Four patients died, one patient was lost to follow-up and two knees were revised before review which was at a minimum of five years. Standard long-leg weight-bearing anteroposterior views of the knee and skyline views of the patellofemoral joint were taken before and at eight months and five years after operation. The radiographs of the remaining 43 knees were reviewed twice by blind and randomised assessment to measure the progression of osteoarthritis within the joints. Overcorrection of the deformity in the coronal plane was avoided in all but two knees. Only one showed evidence of progression of osteoarthritis within the patellofemoral joint, and this was only identified in one of the four assessments. Deterioration in the state of the opposite tibiofemoral compartment was not seen. Varus deformity tended to recur. Recurrent varus of 2° was observed between eight months and five years after operation. There was no correlation between the postoperative tibiofemoral angle and the extent of recurrent varus recorded at five years. Changes in alignment may be indicative of minor polyethylene wear or of subsidence of the tibial component.

The incidence of progressive osteoarthritis within the knee was very low after UKR. Patients should be carefully selected and overcorrection of the deformity be avoided.

We assessed proprioception in the knee using the angle reproduction test in 20 healthy volunteers, ten patients with acute anterior instability and 20 patients with chronic anterior instability after reconstruction of the anterior cruciate ligament (ACL). In addition, the Lysholm-knee score, ligament laxity and patient satisfaction were determined.

Acute trauma causes extensive damage to proprioception which is not restored by rehabilitation alone. Three months after operation, there remained a slight decrease in proprioception compared with the preoperative recordings, but six months after reconstruction, restoration of proprioception was seen near full extension and full flexion. In the mid-range position, proprioception was not restored. At follow-up, 3.7 ± 0.3 years after reconstruction, there was further improvement of proprioception in the mid-range position. There was no difference between open and arthroscopic techniques. The highest correlation was found between proprioception and patient satisfaction. After reconstruction of the ACL reduced proprioception may explain the poor functional outcome in some patients, despite restoration of mechanical stability.

We performed a meta-analysis of the English literature to assess the efficacy of four common regimes for thromboembolic prophylaxis after total knee arthroplasty: aspirin, warfarin, low-molecular-weight heparin (LMWH) and pneumatic compression. We reviewed 136 articles and abstracts published between January 1980 and December 1997. Papers not using routine venography and a lung scan or angiography to detect deep-venous thrombosis (DVT) and pulmonary emboli (PE) respectively, were excluded. Of the 136 studies, 23 with 6001 patients were selected.

The incidence of DVT was 53% (1701/3214) in the aspirin group, 45% (541/1203) in the warfarin group, 29% (311/1075) in the LMWH group, and 17% (86/509) in the pneumatic compression device group. Intermittent pneumatic compression devices and LMWH were significantly better than warfarin (p < 0.0001) or aspirin (p < 0.0001) in preventing DVT.

The incidence of asymptomatic PE was 11.7% in the aspirin group (222/1901), 8.2% (101/1229) in the warfarin group and 6.3% (24/378) in the pneumatic compression group. No studies with LMWH used routine lung scans. Warfarin and pneumatic compression were significantly better than aspirin in preventing asymptomatic PE (p < 0.05).

The incidence of symptomatic PE was 1.3% (23/1800) in the aspirin group, 0.4% (2/559) in the warfarin group, 0.5% (2/416) in the LMWH group and 0% (0/177) in the pneumatic compression group. No statistically significant difference was noted between the above prophylatic regimes due to the very small incidence of symptomatic PE.

Prophylaxis for thromboembolic disease in TKA may have to include a combination of some of the above regimes to incorporate their advantages.