Abnormal sagittal kinematics after total knee replacement (TKR) can adversely affect functional outcome. Two important determinants of knee kinematics are component geometry and the presence or absence of a posterior-stabilising mechanism (cam-post). We investigated the influence of these variables by comparing the kinematics of a TKR with a polyradial femur with a single radius design, both with and without a cam-post mechanism.

We assessed 55 patients, subdivided into four groups, who had undergone a TKR one year earlier by using an established fluoroscopy protocol in order to examine their kinematics in vivo. The kinematic profile was obtained by measuring the patellar tendon angle through the functional knee flexion range (0° to 90°) and the results compared with 14 normal knees. All designs of TKR had abnormal sagittal kinematics compared with the normal knee. There was a significant (p < 0.05) difference between those of the two TKRs near to full extension. The presence of the cam-post mechanism did not influence the kinematics for either TKR design. These differences suggest that surface geometry is a stronger determinant of kinematics than the presence or absence of a cam-post mechanism for these two designs. This may be because the cam-post mechanism is ineffective.

Patients who have undergone total hip or knee replacement (THR and TKR, respectively) are at high risk of venous thromboembolism. We aimed to determine the time courses of both the incidence of venous thromboembolism and effective prophylaxis. Patients with elective primary THR and TKR were enrolled in the multi-national Global Orthopaedic Registry. Data on the incidence of venous thromboembolism and prophylaxis were collected from 6639 THR and 8326 TKR patients.

The cumulative incidence of venous thromboembolism within three months of surgery was 1.7% in the THR and 2.3% in the TKR patients. The mean times to venous thromboembolism were 21.5 days (sd 22.5) for THR, and 9.7 days (sd 14.1) for TKR. It occurred after the median time to discharge in 75% of the THR and 57% of the TKA patients who developed venous thromboembolism. Of those who received recommended forms of prophylaxis, approximately one-quarter (26% of THR and 27% of TKR patients) were not receiving it seven days after surgery, the minimum duration recommended at the time of the study.

The risk of venous thromboembolism extends beyond the usual period of hospitalisation, while the duration of prophylaxis is often shorter than this. Practices should be re-assessed to ensure that patients receive appropriate durations of prophylaxis.

We investigated the pre-operative and one-year post-operative health-related quality of life (HRQOL) outcome by using a Euroqol (EQ-5D) questionnaire in 263 patients who had undergone surgery for herniation of a lumbar disc. Data from the National Swedish Register for lumbar spinal surgery between 2001 and 2002 were used and, in addition, a comparison between our cohort and a Swedish EQ-5D population survey was performed. We analysed the pre- and post-operative quality of life data, age, gender, smoking habits, pain and walking capacity.

The mean age of the patients was 42 years (20 to 66); 155 (59%) were men and 69 (26%) smoked. Pre-operatively, 72 (17%) could walk at least 1 km compared with 200 (76%) postoperatively.

The mean EQ-5D score improved from 0.29 to 0.70, and the HRQOL improved in 195 (74%) of the patients. The pre-operative score did not influence the post-operative score. In most patients, all five EQ-5D dimensions improved, but did not reach the level reported by an age- and gender-matched population sample (mean difference 0.17). Predictors for poor outcome were smoking, a short pre-operative walking distance, and a long history of back pain.

We performed a prospective, randomised trial of 44 patients to compare the functional outcomes of a posterior-cruciate-ligament-retaining and posterior-cruciate-ligament-substituting total knee arthroplasty, and to gain a better understanding of the in vivo kinematic behaviour of both devices.

At follow-up at five years, no statistically significant differences were found in the clinical outcome measurements for either design. The prevalence of radiolucent lines and the survivorship were the same. In a subgroup of 15 knees, additional image-intensifier analysis in the horizontal and sagittal planes was performed during step-up and lunge activity. Our analysis revealed striking differences. Lunge activity showed a mean posterior displacement of both medial and lateral tibiofemoral contact areas (roll-back) which was greater and more consistent in the cruciate-substituting than in the cruciate-retaining group (medial p < 0.0001, lateral p = 0.011). The amount of posterior displacement could predict the maximum flexion which could be achieved (p = 0.018). Forward displacement of the tibiofemoral contact area in flexion during stair activity was seen more in the cruciate-retaining than in the cruciate-substituting group. This was attributed mainly to insufficiency of the posterior cruciate ligament and partially to that of the anterior cruciate ligament. We concluded that, despite similar clinical outcomes, there are significant kinematic differences between cruciate-retaining and cruciate-substituting arthroplasties.

The lateral subvastus approach combined with an osteotomy of the tibial tubercle is a recognised, but rarely used approach for total knee replacement (TKR). A total of 32 patients undergoing primary TKR was randomised into two groups, in one of which the lateral subvastus approach combined with a tibial tubercle osteotomy and in the other the medial parapatellar approach were used. The patients were assessed radiologically and clinically using measurement of the range of movement, a visual analogue patient satisfaction score, the Western Ontario McMasters University Osteoarthritis Index and the American Knee Society score. Four patients were lost to the complete follow-up at two years.

At two years there were no significant differences between the groups in any of the parameters for clinical outcome. In the lateral approach group there was one complication due to displacement of the tibial tubercle osteotomy and two osteotomies took more than six months to unite. In the medial approach group, one patient had a partial tear of the quadriceps. There was a significantly greater incidence of lateral patellar subluxation in the medial approach group (3 of 12) compared with the lateral approach group (0 of 16) (p = 0.034), but without any apparent clinical detriment.

We conclude that the lateral approach with tibial tubercle osteotomy is a safe technique with an outcome comparable with that of the medial parapatellar approach for TKR, but the increased surgical time and its specific complications do not support its routine use. It would seem to be more appropriate to reserve this technique for patients in whom problems with patellar tracking are anticipated.

A series of 100 consecutive osteoarthritic patients was randomised to undergo total knee replacement using a Miller-Galante II prosthesis, with or without a cemented polyethylene patellar component. Knee function was evaluated using the American Knee Society score, Western Ontario and McMaster University Osteoarthritis index, specific patellofemoral-related questions and radiographic evaluation until the fourth post-operative year, then via questionnaire until ten years post-operatively. A ten-point difference in the American Knee Society score between the two groups was considered a significant change in knee performance, with α and β levels of 0.05.

The mean age of the patients in the resurfaced group was 71 years (53 to 88) and in the non-resurfaced group was 73 years (54 to 86).

After ten years 22 patients had died, seven were suffering from dementia, three declined further participation and ten were lost to follow-up. Two patients in the non-resurfaced group subsequently had their patellae resurfaced. In the resurfaced group one patient had an arthroscopic lateral release. There was no significant difference between the two treatment groups: both had a similar deterioration of scores with time, and no further patellofemoral complications were observed in either group.

We are unable to recommend routine patellar resurfacing in osteoarthritic patients undergoing total knee replacement on the basis of our findings.