We carried out a prospective randomised study to evaluate the blood loss in 60 patients having a total knee arthroplasty and divided randomly into two equal groups, one having a computer-assisted procedure and the other a standard operation. The surgery was carried out by a single surgeon at one institution using a uniform approach. The only variable in the groups was the use of intramedullary femoral and tibial alignment jigs in the standard group and single tracker pins of the imageless navigation system in the tibia and femur in the navigated group. The mean drainage of blood was 1351 ml (715 to 2890; 95% confidence interval (CI) 1183 to 1518) in the computer-aided group and 1747 ml (1100 to 3030; CI 1581 to 1912) in the conventional group. This difference was statistically significant (p = 0.001). The mean calculated loss of haemoglobin was 36 g/dl in the navigated group versus 53 g/dl in the conventional group; this was significant at p < 0.00001. There was a highly significant reduction in blood drainage and the calculated Hb loss between the computer-assisted and the conventional techniques. This allows the ordering of less blood before the operation, reduces risks at transfusion and gives financial saving. Computer-assisted surgery may also be useful for patients in whom blood products are not acceptable

The results of total knee replacement in five patients aged between 22 and 37 with severe haemophilia A or B are described. All patients had been managed conservatively without success. Frequent bleeds, severe pain and limitation of movement were the indications for operation. Despite close haematological surveillance, bleeding problems occurred in three of the patients and large quantities of plasma concentrates were required. Review of the patients over a period of 25 to 48 months after operation showed dramatic lessening of pain and maintenance of a satisfactory range of movement. The frequency of haemarthrosis diminished markedly and the requirements for factor concentrate in the years after operation fell substantially. Two patients returned to employment. Total knee replacement led to marked clinical improvement in all the patients, but the long-term results are not yet known

We performed a CT-based computer simulation study to determine how the relationship between any inbuilt posterior slope in the proximal tibial osteotomy and cutting jig rotational orientation errors affect tibial component alignment in total knee replacement. Four different posterior slopes (3°, 5°, 7° and 10°), each with a rotational error of 5°, 10°, 15°, 20°, 25° or 30°, were simulated. Tibial cutting block malalignment of 20° of external rotation can produce varus malalignment of 2.4° and 3.5° with a 7° and a 10° sloped cutting jig, respectively. Care must be taken in orientating the cutting jig in the sagittal plane when making a posterior sloped proximal tibial osteotomy in total knee replacement. Cite this article: Bone Joint J 2013;95-B:1201–3

The results of total knee replacement (TKR) are commonly assessed by survival analysis using revision as the endpoint. We have used the assessment of pain by a patient-based questionnaire as an alternative. In one hospital, 1429 TKRs were inserted by 66 surgeons between 1987 and 1993. The survival at seven years, with revision as the endpoint, was 97.5% (CI 94 to 100). There were no significant differences between the three different types of implant used, the AGC, the IB2 and the Nuffield Knee. When the endpoint was the development of moderate pain, the survival at seven years for the AGC knee was 72% and that for the IB2 was similar. Significantly more patients (p = 0.007) with the Nuffield Knee, however, had developed moderate pain. Using revision as the endpoint, it is difficult to discriminate between the various types of TKR, but this can be achieved using pain. In this investigation 30% of the patients reported moderate pain at some stage by seven years from operation

We report the long-term results of the management of neglected chronically infected total knee replacements with a two-stage re-implantation protocol. In 18 of 34 patients (53%) a resistant organism was isolated. All cases were treated by the same surgical team in a specialist centre and had a mean follow-up of 12.1 years (10 to 14). They were evaluated clinically and radiologically using the Knee Society Score (KSS) and the American Knee Society Roentgenographic scoring system, respectively. One patient died after eight years from an unrelated cause and two were lost to follow-up. Three patients (8.8%) developed a recurrent infection for which further surgery was required. The infection was eradicated successfully in 31 patients (91.1%). There was one case of aseptic loosening after 13 years. We found a significant improvement in the KSS at final follow-up (p < 0.001)

Intra-operative, peri-articular injection of local anaesthesia is an increasingly popular way of controlling pain following total knee replacement. At the same time, the problems associated with allogenic blood transfusion have led to interest in alternative methods for managing blood loss after total knee replacement, including the use of auto-transfusion of fluid from the patient’s surgical drain. It is safe to combine peri-articular infiltration with auto-transfusion from the drain. We performed a randomised clinical trial to compare the concentration of local anaesthetic in the blood and in the fluid collected in the knee drain in patients having either a peri-articular injection or a femoral nerve block. Clinically relevant concentrations of local anaesthetic were found in the fluid from the drains of patients having peri-articular injections (4.92 μg/ml (. sd. 3.151)). However, none of the patients having femoral nerve blockade had detectable levels. None of the patients in either group had clinically relevant concentrations of local anaesthetic in their blood after re-transfusion. The evidence from this study suggests that it is safe to use peri-articular injection in combination with auto-transfusion of blood from peri-articular drains during knee replacement surgery

Between 1992 and 1994 we performed a prospective study of the effect of total knee replacement (TKR) on the health status of 119 patients over the age of 80 years who had had a primary unilateral TKR. The Nottingham Health Profile was used to assess this before and at three and 12 months after operation. We found a significant improvement in the scores for pain, emotional reaction, sleep and physical mobility at three months. After 12 months, the scores for pain and sleep were well maintained. The other factors had deteriorated slightly but remained better than before operation. Our findings show that TKR leads to a significant improvement in the general health status of the very elderly

We carried out three total knee replacements with proximal realignment in two patients with severe osteoarthritis of the knee and congenital dislocation of the patella. During the operation, the femur and the tibia were cut according to the recommendations of the manufacturer of the implant. The femoral component was placed in external rotation and the centre of the tibial component aligned in relation to the tibial tuberosity with regard to rotation and translation. After making the bone cuts, the iliotibial tract was detached from Gerdy’s tubercle, the popliteus tendon divided, and the biceps femoris tendon elongated by Z-plasty. After the trial implants were positioned, a proximal re-alignment procedure was performed. One knee had deep infection. There was one dislocated patella which was repositioned, and walking ability was improved in all knees. We believe that the rotational alignment of a prosthesis is as important as the soft-tissue surgery

In posterior stabilised total knee replacement (TKR) a larger femoral component is sometimes selected to manage the increased flexion gap caused by resection of the posterior cruciate ligament. However, concerns remain regarding the adverse effect of the increased anteroposterior dimensions of the femoral component on the patellofemoral (PF) joint. Meanwhile, the gender-specific femoral component has a narrower and thinner anterior flange and is expected to reduce the PF contact force. PF contact forces were measured at 90°, 120°, 130° and 140° of flexion using the NexGen Legacy Posterior Stabilized (LPS)-Flex Fixed Bearing Knee system using Standard, Upsized and Gender femoral components during TKR. Increasing the size of the femoral component significantly increased mean PF forces at 120°, 130° and 140° of flexion (p = 0.005, p < 0.001 and p < 0.001, respectively). No difference was found in contact force between the Gender and the Standard components. Among the patients who had overhang of the Standard component, mean contact forces with the Gender component were slightly lower than those of the Standard component, but no statistical difference was found at 90°, 120°, 130° or 140° of flexion (p = 0.689, 0.615, 0.253 and 0.248, respectively). Upsized femoral components would increase PF forces in deep knee flexion. Gender-specific implants would not reduce PF forces

We undertook a prospective, randomised study in order to evaluate the efficacy of clamping the drains after intra-articular injection of saline with 1:500 000 adrenaline compared with post-operative blood salvage in reducing blood loss in 212 total knee arthroplasties. The mean post-operative drained blood volume after drain clamping was 352.1 ml compared to 662.3 ml after blood salvage (p < 0.0001). Allogenic blood transfusion was needed in one patient in the drain group and for three in the blood salvage group. Drain clamping with intra-articular injection of saline with adrenaline is more effective than post-operative autologous blood transfusion in reducing blood loss during total knee arthroplasty

We analysed the serum C-reactive protein level, synovial fluid obtained by joint aspiration and five synovial biopsies from 145 knee replacements prior to revision to assess the value of these parameters in diagnosing late peri-prosthetic infection. Five further synovial biopsies were used for histological analysis. Samples were also obtained during the revision and incubated and analysed in an identical manner for 14 days. A total of 40 total knee replacements were found to be infected (prevalence 27.6%). The aspiration technique had a sensitivity of 72.5% (95% confidence interval (CI) 58.7 to 86.3), a specificity of 95.2% (95% CI 91.2 to 99.2), a positive predictive value of 85.3% (95% CI 73.4 to 100), a negative predictive value of 90.1% (95% CI 84.5 to 95.7) and an accuracy of 89%. The biopsy technique had a sensitivity of 100%, a specificity of 98.1% (95% CI 95.5 to 100), a positive predictive value of 95.2% (95% CI 88.8 to 100), a negative predictive value of 100% and an accuracy of 98.6%. C-reactive protein with a cut-off-point of 13.5 mg/l had a sensitivity of 72.5% (95% CI 58.7 to 86.3), a specificity of 80.9% (95% CI 73.4 to 88.4), a positive predictive value of 59.2% (95% CI 45.4 to 73.0), a negative predictive value of 88.5% (95% 81.0 to 96.0 CI) and an accuracy of 78.1%. We found that biopsy was superior to joint aspiration and C-reactive protein in the diagnosis of late peri-prosthetic infection of total knee replacements

We previously compared the component alignment in total knee replacement using a computer-navigated technique with a conventional jig-based method. We randomly allocated 71 patients to undergo either computer-navigated or conventional replacement. An improved alignment was seen in the computer-navigated group. The patients were then followed up post-operatively for two years, using the Knee Society score, the Short Form-36 health survey, the Western Ontario and McMaster Universities osteoarthritis index, the Bartlett Patellar pain questionnaire and the Oxford knee score, to assess functional outcome. At two years post-operatively 60 patients were available for assessment, 30 in each group and 62 patients completed a postal survey. No patient in either group had undergone revision. All variables were analysed for differences between the groups either by Student’s t-test or the Mann-Whitney U test. Differences between the two groups did not reach significance for any of the outcome measures at any time point. At two years postoperatively, the frequency of mild to severe anterior pain was not significantly different (p = 0.818), varying between 44% (14) for the computer-navigated group, and 47% (14) for the conventionally-replaced group. The Bartlett Patellar score and the Oxford knee score were also not significantly different (t-test p = 0.161 and p = 0.607, respectively). The clinical outcome of the patients with a computer-navigated knee replacement appears to be no different to that of a more conventional jig-based technique at two years post-operatively, despite the better alignment achieved with computer-navigated surgery

As part of the national initiative to reduce waiting times for joint replacement surgery in Wales, the Cardiff and Vale NHS Trust referred 224 patients to the NHS Treatment Centre in Weston-Super-Mare for total knee replacement (TKR). A total of 258 Kinemax TKRs were performed between November 2004 and August 2006. Of these, a total of 199 patients (232 TKRs, 90%) have been followed up for five years. This cohort was compared with 258 consecutive TKRs in 250 patients, performed at Cardiff and Vale Orthopaedic Centre (CAVOC) over a similar time period. The five year cumulative survival rate was 80.6% (95% confidence interval (CI) 74.0 to 86.0) in the Weston-Super-Mare cohort and 95.0% (95% CI 90.2 to 98.2) in the CAVOC cohort with revision for any reason as the endpoint. The relative risk for revision at Weston-Super-Mare compared with CAVOC was 3.88 (p < 0.001). For implants surviving five years, the mean Oxford knee scores (OKS) and mean EuroQol (EQ-5D) scores were similar (OKS: Weston-Super-Mare 29 (2 to 47) vs CAVOC 29.8 (3 to 48), p = 0.61; EQ-5D: Weston-Super-Mare 0.53 (-0.38 to 1.00) vs CAVOC 0.55 (-0.32 to 1.00), p = 0.79). Patients with revised TKRs had significantly lower Oxford knee and EQ-5D scores (p < 0.001). The results show a higher revision rate for patients operated at Weston-Super-Mare Treatment Centre, with a reduction in functional outcome and quality of life after revision. This further confirms that patients moved from one area to another for joint replacement surgery fare poorly

Component malalignment can be associated with pain following total knee replacement (TKR). Using MRI, we reviewed 50 patients with painful TKRs and compared them with a group of 16 asymptomatic controls to determine the feasibility of using MRI in evaluating the rotational alignment of the components. Using the additional soft-tissue detail provided by this modality, we also evaluated the extent of synovitis within these two groups. Angular measurements were based on the femoral transepicondylar axis and tibial tubercle. Between two observers, there was very high interobserver agreement in the measurements of all values. Patients with painful TKRs demonstrated statistically significant relative internal rotation of the femoral component (p = 0.030). There was relative internal rotation of the tibial to femoral component and combined excessive internal rotation of the components in symptomatic knees, although these results were significant only with one of the observers (p = 0.031). There was a statistically significant association between the presence and severity of synovitis and painful TKR (p < 0.001). MRI is an effective modality in evaluating component rotational alignment

We studied the influence of soft-tissue releases and soft-tissue balance on the outcome of 526 total knee replacements one year after operation. The surgery had been performed by seven surgeons in five centres in the United Kingdom between October 1999 and December 2002. Balancing was carried out by five surgeons using spacers and trials and by two surgeons using a ‘balancer’ instrument. All the surgeons assessed the adequacy of their releases by taking measurements with the balancer after soft-tissue release before implanting the components. Independent observers collected the Oxford knee scores and applied the American Knee Society functional and knee scores as well as recording the range of movement of the replaced knee. These were compared with the pre-operative scores and the extent of the releases. We found differences in outcomes between minimal and extensive releases and between balanced and imbalanced knees. Knees requiring extensive soft-tissue releases showed greater change in the short-term clinical outcome without increased complications and achieved similar results at one year compared with those with less deformity pre-operatively which had required less soft-tissue release. Balancing an imbalanced knee improved the short-term knee outcome

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 present a series of 48 patients with infected total knee replacements managed by the use of articulating cement spacers and short-term parenteral antibiotic therapy in the postoperative period. All patients had microbiological and/or histological confirmation of infection at the first stage of their revision. They all underwent re-implantation and had a mean follow-up of 48.5 months (26 to 85). Infection was successfully eradicated in 42 of the 48 patients (88%). Six had persistent infection which led to recurrence of symptoms and further surgery was successful in eliminating infection in four patients. These rates of success are similar to those of other comparable series. We conclude that protracted courses of intravenous antibiotic treatment may not be necessary in the management of the infected total knee replacement. In addition, we analysed the microbiological, histological and serological results obtained at the time of re-implantation of the definitive prosthesis, but could not identify a single test which alone would accurately predict a successful outcome

The object of this study was to develop a method to assess the accuracy of an image-free total knee replacement navigation system in legs with normal or abnormal mechanical axes. A phantom leg was constructed with simulated hip and knee joints and provided a means to locate the centre of the ankle joint. Additional joints located at the midshaft of the tibia and femur allowed deformation in the flexion/extension, varus/valgus and rotational planes. Using a digital caliper unit to measure the coordinates precisely, a software program was developed to convert these local coordinates into a determination of actual leg alignment. At specific points in the procedure, information was compared between the digital caliper measurements and the image-free navigation system. Repeated serial measurements were undertaken. In the setting of normal alignment the mean error of the system was within 0.5°. In the setting of abnormal plane alignment in both the femur and the tibia, the error was within 1°. This is the first study designed to assess the accuracy of a clinically-validated navigation system. It demonstrates in vitro accuracy of the image-free navigation system in both normal and abnormal leg alignment settings

We compared patient-reported outcomes of the Kinemax fixed- and mobile-bearing total knee replacement in a multi-centre randomised controlled trial. Patients were randomised to the fixed- or the mobile-bearing prosthesis via a sealed envelope method after the bone cuts had been made in the operating theatre. Randomisation was stratified by centre and diagnosis. Patients were assessed pre-operatively and at eight to 12 weeks, one year and two years post-operatively. Validated questionnaires were used which included the Western Ontario MacMasters University, Short-Form 12, Mental Health Index-5, Knee Injury and Osteoarthritis Outcome Score for Knee-Related Quality of Life and Function in Sport and Recreation scales and a validated scale of satisfaction post-operatively. In total, 242 patients (250 knees) with a mean age of 68 years (40 to 80) were recruited from four NHS orthopaedic centres. Of these, 132 patients (54.5%) were women. No statistically significant differences could be identified in any of the patient-reported outcome scores between patients who received the fixed-bearing or the mobile-bearing knee up to two-years post-operatively

We measured the contact areas and contact stresses at the post-cam mechanism of a posterior-stabilised total knee arthroplasty when a posterior force of 500 N was applied to the Kirschner Performance, Scorpio Superflex, NexGen LPS Flex Fixed, and NexGen LPS Flex Mobile knee systems. Measurements were made at 90°, 120°, and 150° of flexion both in neutral rotation and 10° of internal rotation of the tibial component. Peak contact stresses at 90°, 120°, and 150° were 24.0, 33.9, and 28.8 MPa, respectively, for the Kirschner; 26.0, 32.4, and 22.1 MPa, respectively, for the Scorpio; and 34.1, 31.5, and 32.5 MPa, respectively, for the NexGen LPS Flex Fixed. With an internally rotated tibia, the contact stress increased significantly with all the fixed-bearing arthroplasties but not with the NexGen LPS Flex Mobile arthroplasty. The post-cam design should be modified in order to provide a larger contact area whilst avoiding any impingement and edge loading