224 patients from the Cardiff and Vale NHS Trust who had total knee replacements at the NHS Treatment Centre in Weston-Super-Mare by surgeons from overseas appeared to have significantly worse results than those recorded in the published literature. We wished to establish whether a group of patients treated in the same hospital with the same prosthesis at a similar time by local NHS orthopaedic surgeons in substantive posts would have a similar outcome.

Follow-up of all 214 patients (223 knee replacements) treated in 2004 was conducted with questionnaires, clinical review and x-ray assessment. In cases of no response, contact was made with GPs to establish the outcome of the surgery.

The outcome of all patients was known and of the 125 knee replacements available for clinical review at six years (mean), 119 cases (96%) achieved satisfactory coronal alignment with reference to the published literature. There were six revisions, five for loosening and one for malalignment. The cumulative survival rate for re-operation at six years was 97.2% (95% confidence interval 95.2 to 99.1).

This study shows that the results of total knee replacement performed by a group of NHS orthopaedic surgeons were comparable with other institutions and were significantly better than those reported from the NHS Treatment Centre in Weston-Super-Mare, using the same facilities and implant over the same period of time. This work supports previous recommendations for single surgeon supervision of the patient pathway and appropriate follow-up procedures.

Introduction: The rate of homologous blood transfusion following primary total hip replacement (THR) can be as high as 30–40% and is not without risk. Postoperative blood salvage (POS) with autologous blood transfusion may minimize the necessity for HBT but the clinical, haematological and economic benefits have yet to be clearly demonstrated for primary THR.

The aim of this prospective randomized study was to determine if the use of POS affects postoperative haemoglobin and haematocrit values and reduces the rate of homologous blood transfusion. Secondary outcomes measures included length of hospital stay and patient satisfaction. A cost analysis was conducted on the basis of the results.

Methods: Calculations following a preliminary study revealed that 72 patients would be required in each group to detect a significant difference of 0.7 gdL⁻¹ in the post operative haemoglobin level (with power of 80% and an α value of 0.05). The patients were block randomized on reduction of the primary THR, prior to closure, to receive either two vacuum drains or the autologous retransfusion system.

Results: There were 82 patients in the vacuum drain group and 76 patients in the autologous retransfusion group. Haemoglobin and haematocrit values were not significantly different between the groups but significantly fewer patients with the autologous system had a postoperative haemoglobin value < 9.0 gdL⁻¹ (8% vs. 20%, p = 0.035). Significantly fewer patients with the autologous system required HBT (8% vs. 21%, p = 0.022). There was an overall cost saving in this group.

Discussion: This study confirms that POS results in significantly fewer patients with a post-operative Hb below 9.0 gdL⁻¹ and confirms that POS significantly reduces the necessity for homologous blood transfusion following primary THR. As a result, our unit uses the autologous retransfusion system for primary THR.

Homologous blood transfusion (HBT) following primary total hip replacement (THR) is not without risk. Postoperative blood salvage (POS) with autologous blood transfusion may minimize the necessity for HBT but the clinical, haematological and economic benefits have yet to be clearly demonstrated for primary THR.

The aim of this randomized prospective study was to determine if the use of POS affects postoperative haemoglobin levels, haematocrit and HBT requirement. Secondary outcomes included length of stay and patient satisfaction. A cost analysis was conducted on the basis of the results. The patients were randomized at the point of reduction of the primary THR to receive either two vacuum drains (82 patients) or an autologous retransfusion system (76 patients).

Haemoglobin and haematocrit values were not significantly different between groups but significantly fewer patients with the autologous system had a postoperative haemoglobin value < 9.0 gdL⁻¹ (8% vs. 20%, p = 0.035). Significantly fewer patients with the autologous system required HBT (8% vs. 21%, p = 0.022). There was an overall cost saving in this group.

This study has shown that use of an autologous retransfusion system for primary THR reduces the necessity for HBT and is cost effective.

Joint fluids obtained for diagnostic purposes from 25 patients were assayed for the presence of gentamicin. All of the patients had presented with failing or painful joints at periods up to 10 years following primary hip or knee arthroplasty using gentamicin-impregnated cement. Gentamicin was detected in the joint fluids from 9 of 15 patients with knee prostheses and 4 of 10 with hip prostheses. Gentamicin concentrations ranged from 0.06mg/L to 0.85 mg/L with no significant differences in concentration between patients with hip or knee prostheses, or type of prosthesis, and no identifiable relationship was found gentamicin concentration and the time after primary arthroplasty. Although the majority of the gentamicin concentrations were found to be below the levels required to inhibit susceptible pathogens, we conclude that gentamicin release around failing implants may lead to false negative cultures in some patients and provide selective pressure for the emergence of resistance where infection is present in others.

Three cases of posterior dislocation of the Kinemax Posterior- Stabilized total knee replacement are reported, and predisposing factors, including operative technique and prosthesis design, are discussed.

All three patients underwent posterior-stabilised knee replacement surgery at the Avon Orthopaedic Centre for osteoarthritis, between 1984 and 2000. In all cases the patient represented to the Emergency Department of a local hospital with posterior dislocation, at between 9 months and 6 years postoperatively. The mechanism for dislocation was hyperflexion of the knee.

The dislocations could not be reduced under sedation because of obstruction by the protruding tibial insert, and required general anaesthesia to disengage the components. In all cases posterior dislocation became recurrent problem, and further surgery was required to address the instability. Two of the three patients underwent exchange of their stabilised tibial inserts for thicker versions of the same design, in order to reduce the excessive laxity present in flexion. The third patient underwent exploratory surgery and it was found that his patellar button had separated from the underlying bone. The patella was therefore resurfaced, restoring the integrity of his extensor mechanism. No further dislocations have occurred in any of the three patients.

The causes of posterior dislocation of posterior-stabilized total knee replacements are multifactorial. They include malrotation of the tibial component, although this was not found to be the case in the three patients reported here. The design of the prosthesis may also contribute, and the upsloping and relatively shallow tibial spine of the Kinemax prosthesis (Howmedica) appears to be less forgiving than others. This is particularly the case if soft tissue lateral release or excessive resection of the posterior condyles has produced an increased flexiongap and therefore excessive flexion laxity. Our cases demonstrate the pitfalls that can produce this uncommon but serious complication, some of which can be predicted preoperatively, particularly in the patient with a valgus knee or deficiency of the extensor mechanism.