Aim: Our goal was to evaluate the short term result of medial unicondylar arthroplasty in a valgus knee and to determine the reason for medial compartment osteoarthritis (OA) in a valgus knee. Material and method: Between 1997–2001 312 unicondylar arthroplasties have been carried out at our department. 8 were lateral the others were all medial. Of the 304 medial 10 were done for a valgus knee. We examined the pre- and postoperative mechanical and anatomical axis. We rated the knees using the American Knee Society Knee Score on avarage at 5 years follow-up. Intra- and postoperative complications, revisions are noted. Results: All of the knees had an anatomical axis of increased valgus. The mechanical axis differed, from 3 degrees of varus to 4 degrees of valgus. 8 of the patients rated the result excellent or good. 1 had an acceptable result, 1 had a revision. Conclusion: Medial compartment OA can develop in a knee with an anatomical axis in valgus, and a mechanical axis of varus. It can be succesfully treated with medial unicondylar arthroplasty. The results are similar to medial unicondylar arthroplasty in a varus knee

Unlike tri-compartmental arthroplasty, unicompartmental knee arthroplasties (UKAs) correct only osteochondral condylar defects and do not include any ligament balancing. Pre-operative deformities of more than 20° strongly suggest that UKA is not indicated. Best results are generally obtained by avoiding hypercorrection and not exceeding 5° of residual deformity post-operatively. Since 1997, 112 UKAs have been implanted. We performed tibial osteotomies with respect to tibial plateau inclination in the frontal plane (metaphyseal axis). Our patients were pre-operatively studied and then re-evaluated after a mean follow-up of 4 years. We used the GIUM (Gruppo Italiano Utilizzatori Monocompartimentali) scoring system. Pre-operative and post-operative radiograms from all patients were collected, and then we correlated the amount of correction of lower limb mechanical axis with GIUM score for each patient. Mean pre-operative mechanical axis of the lower limb showed a varus deformity of 7.43°, whereas post-operative values averaged 5.56° of varus deformity, with a minimal valgus correction of the deformity. Thus, correction of angular deformity was statistically negligible (p> 0.5). Mean pre-operative GIUM score was 20.3, whereas mean post-operative score was 71.6 (p< 0.001). Correlation between entity of correction and GIUM score was significant (r=0.76). The amount of angular correction of the mechanical axis of the lower limb was statistically significant in influencing functional outcomes (p< 0.05). The best results are obtained by correcting excessively valgus knees to a physiologic range, while varus knees have to be minimally corrected. The worst results are obtained with greatest modifications of the mechanical axis of the lower limb.

Introduction and Aims: We present a review of the long-term results of custom-made massive unicondylar femoral replacement for reconstruction following tumor excision, and compare the functional outcome of this procedure with prosthetic distal femoral replacement. Method: Using our centre’s endoprosthetic database we identified and analysed all cases of massive unicondylar femoral replacement performed at our unit (group 1). Patients were evaluated for function, (Musculoskeletal Tumour Society System), and for stability (adapted from Oxford Knee Score). An age and sex-matched cohort of patients who had undergone distal femoral replacements for similar pathologies, and in who the follow-up was of a comparable time period (group 2) was evaluated in an identical manner. Statistical analysis was performed on the results. Results: Twelve cases of massive unicondylar replacement have been performed between 1990 and 2001, for a variety of malignant and benign tumors. There have been no incidences of infection, aseptic loosening or tumor recurrence. One patient has died of metastatic disease and another has undergone revision to distal femoral replacement for osteoarthritis. Of the remaining 10 patients, nine were available for assessment. Each of the two groups consisted of five males and four females, with mean age 48 years in group 1 and 49 years in group 2. The average follow-up since surgery in both groups was 10 years. The mean MSTS and stability scores of group 1 were 83% and 3.9 respectively, and 71% and 3.2 for group 2; the difference in scores between groups was statistically significant (p< 0.02). Conclusion: With stringent case selection criteria, the custom-made massive unicondylar femoral replacement produces a good outcome, with functional results significantly better than distal femoral replacement. This may be because a substantial proportion of the knee joint with at least one cruciate and one collateral ligament are kept intact, thus facilitating enhanced proprioception

Introduction: We present a review of the long-term results of custom-made massive unicondylar femoral replacement for reconstruction following tumour excision, and compare the functional outcome of this procedure with prosthetic distal femoral replacement. Method: Using our centre’s endoprosthetic database we identified and analysed all cases of massive unicondylar femoral replacement performed at our unit (group 1). Patients were evaluated for function, (Musculoskeletal Tumour Society System), and for stability (adapted from Oxford Knee Score). An age and sex-matched cohort of patients who had undergone distal femoral replacements for similar pathologies, and in who the follow-up was of a comparable time period (group 2) was evaluated in an identical manner. Statistical analysis was performed on the results. Results: Twelve cases of massive unicondylar replacement have been performed between 1990 and 2001, for a variety of malignant and benign tumours. There have been no incidences of infection, aseptic loosening or tumour recurrence. One patient has died of metastatic disease and another has undergone revision to distal femoral replacement for osteoarthritis. Of the remaining ten patients, nine were available for assessment Each of the two groups consisted of 5 males and 4 females, with mean age 48 years in group 1 and 49 years in group 2. The average follow-up since surgery in both groups was 10 years. The mean MSTS and stability scores of group 1 were 83% and 3.9 respectively, and 71% and 3.2 for group 2; the difference in scores between groups was statistically significant, (p< 0.02). Conclusion: With stringent case selection criteria, the custom-made massive unicondylar femoral replacement generally produces a good outcome, with functional results significantly better than distal femoral replacement. This may be because a substantial proportion of the knee joint with at least one cruciate and one collateral ligament are kept intact, thus facilitating enhanced proprioception

In 1972, unicondylar arthroplasty (UKA) was introduced, along with total knee arthroplasty (TKA), as an option for managing gonarthrosis. Although the early clinical results with the first generation of implants were equivalent to those of total knee arthroplasty, little interest in UKA was sustained. If unicondylar arthroplasty is to realise a role in the management of degenerative arthritis, even as a temporising procedure, the results must be predictable and reproducible. Patient satisfaction must be equivalent to or better than that of TKA. Finally, the conversion of UKA to TKA must be uncomplicated, avoiding complex reconstructive procedures and the use of revision implants. UKA achieves these goals. As documented by such things as reduced blood loss and risk of infection, morbidity has always been less with unicondylar arthroplasty. Patients with both a UKA and a TKA on the contralateral side generally prefer the unicondylar knee. This is partly because a UKA provides a superior range of motion and better function with such activities as stair climbing. Adapting the surgery to an outpatient operative procedure using a minimally invasive incision has enhanced patient satisfaction. In most studies, the revision of a failed unicondylar arthroplasty using primary TKA components has been predictable and durable. Osteolysis has not been reported with failed UKA; therefore bone defects usually are minimal. If major tibial bone defects are present, a revision tibial component and proper bone defect management will achieve excellent results. In conclusion, we cannot only justify UKA as a temporising procedure, but also as a definitive procedure with long-term results that are comparable to TKA for gonarthrosis

Recently in the literature the indications of unicompartmental knee arthroplasty have been extended by the inclusion of patients with arthritis which is predominantly but not exclusively effecting the medial compartment. The aim of this study is to evaluate the outcome of MAKO unicondylar replacement in the treatment of knee osteoarthritis after the initial surgical insult is worn off to evaluate the impact of residual patellofemoral and lateral osteoarthritis on the outcome of medial unicompartmental knee replacement. 135 patients who underwent uncomplicated 144 MAKO medial unicondylar replacements for knee arthritis were identified and studied. Original radiographs were used to classify severity of patellofemoral and lateral compartmental osteoarthritis in these patients. Severity of patellofemoral and lateral compartmental osteoarthritis was analyzed against Oxford and Knee Society (AKSS) scores and amount of ipsilateral residual knee symptoms at 6 months post-operative period. Pre-operative Oxford and Knee Society scores, and other comorbidities and long term disability were studied as confounding variables. We found significant improvement in symptoms and scores in spite of other compartment disease. Poorer outcome was seen in association with comorbidities and long term disability but not when radiographic signs of arthritis in the other compartments were present. Six patients required revision of which three had (lateral facet) patellofemoral disease in the original x-rays. In conclusion there is no direct relationship between postoperative symptoms and poor outcome and radiographic disease in the other compartments. However when symptoms are severe enough to necessitate revision this is due to patellofemoral and not lateral compartment disease

Introduction. The purpose of this study was to characterize the recovery of physical activity following knee arthroplasty by means of step counts and flight counts (flights of stairs) measured using a smartphone-based care platform. Methods. This is a secondary data analysis on the treatment cohort of a multicenter prospective trial evaluating the use of a smartphone-based care platform for primary total and unicondylar joint arthroplasty. Participants in the treatment arm that underwent primary total or unicondylar knee arthroplasty and had at least 3 months of follow-up were included (n=367). Participants were provided the app with an associated smart watch for measuring several different health measures including daily step and flight counts. These measures were monitored preoperatively, and the following postoperative intervals were selected for review: 2–4 days, 1 month, 1.5 month, 3 months and 6 months. The data are presented as mean, standard deviation, median, and interquartile range (IQR). Signed rank tests were used to assess the difference in average of daily step counts over time. As not all patients reported having multiple stairs at home, a separate analysis was also performed on average flights of stairs (n=214). A sub-study was performed to evaluate patients who returned to preoperative levels at 1.5 months (step count) and 3 months (flight count) using an independent samples T test or Fisher's Exact test was to compare demographics between patients that returned to preoperative levels and those that did not. Results. The mean age of the step count population was 63.1 ± 8.3 years and 64.31% were female, 35.69% were male. The mean body mass index was 31.1 ± 5.9 kg/m. 2. For those who reported multiple stairs at home, the mean age was 62.6 ± 8.3 years and 62.3% were female. The mean body mass index was 30.7 ± 5.4 kg/m. 2. . As expected, the immediate post-op (2–4 days) step count (median 1257.5 steps, IQR 523 – 2267) was significantly lower than preop (median 4160 steps, IQR 2669 – 6034, p < 0.001). Approximately 50% of patients returned to preoperative step counts by 1.5 months postoperatively with a median 4,504 steps (IQR, 2711, 6121, p=0.8230, Figure 1). Improvements in step count continued throughout the remainder of follow-up with the 6-month follow-up visit (median 5517 steps, IQR 3888 – 7279) showing the greatest magnitude (p<0.001). In patients who reported stairs in their homes, approximately 64% of subjects returned to pre-op flight counts by 3 months (p=0.085), followed similar trends with significant improvements at 6 months (p=0.003). Finally, there was no difference in age, sex, BMI, or operative knee between those that returned to mean preoperative step or flight counts by 1.5 months and 3 months, respectively. Discussion and Conclusion. These data demonstrated a recovery curve similar to previously reported curves for patient reported outcome measures in the arthroplasty arena. Patients and surgeons may use this information to help set goals for recovery following total and unicondylar knee arthroplasty using objective activity measures. For any figures or tables, please contact the authors directly

Aim: Cementation of tibial implants in total knee arthroplasty is a gold-standard considering the high loosening rates of cementless implants. In contrast, only sparse data exist regarding unicondylar arthroplasty due to limited use. In this study, we compare cemented with cementless unicondylar knee arthroplasty and aim to define both clinical and radiological differences in treatment outcome. Materials and Methods: In a retrospective study, 106 patients who had undergone a medial unicondylar replacement were examined after a mean postoperative period of 8 years. Of these, 42 patients (median age 81±7 years) had received a cemented and 64 (median age 73±7 years) a cementless knee arthroplasty by the same surgeon while 7 patients were deceased or could not be reached. Well-established clinical (VAS, HSS, KSS, UCLA, WOMAC) and quality of life (SF-36) scores were used to evaluate treatment outcome. X-rays were performed to evaluate periprosthetic loosening zones, according to Ewald’s criteria. Results: The cementless patient group presented significantly better clinical scores (HSS, KSS, UCLA, WOMAC), except in the Visual Analogue Scale (VAS) for pain assessment. The quality of life was significantly better in the cementless group except in the subgroups concerning physical function, vitality and social role, which resembled normal population. Moreover, radiographic analysis using antero-posterior X-rays revealed significantly more and larger periprosthetic loosening areas in tibial zone 2 in the cementless group. Conclusion: The inferior clinical results characterising the cemented group could be attributed to the higher mean age. Regarding the radiological loosening zones, we did not detect any differences in the techniques of fixation, although physical activity and mechanical stresses were higher in the cementless group

Purpose: A retrospective review was done to evaluate survival of unicondylar arthroplasty and identify factors that increased the odds of revision. Our hypothesis was that younger age, increased weight, use of a thinner tibial component, polyethylene shelf aging. Methods: 411 medial compartment unicondylar arthroplasties encompassing 12 designs were performed at one institution from 1984 to 1998. Patient age and weight averaged 67 ± 8 years and 83 ± 15 kg, respectively. Eighty-seven percent of the tibial components were metal-backed. Initial tibial component thickness averaged 8.5 ±1mm. Polyethylene shelf age averaged 1.3 ± 1.2 years. Results: Four factors made revision more likely (p < 0.05, Cox proportional hazards regression): younger patient age, thinner tibial component, longer polyethylene shelf age. Gender and weight did not influence survival. With an endpoint of any component revision, Kaplan-Meier survival at nine postoperative years was 80% (95% confidence interval: 75% to 84%). In knees in which tibial component initial thickness was greater than 7mm and polyethylene shelf age was under 1 year, nine-year survival was 94% (95% confidence interval: 91% to 99%). Conclusions: A 94% likelihood of survival at nine postoperative years may be a reasonable expectation when the procedure is performed with appropriate materials and designs. Funding: Commerical funding. Funding Parties: Inova Health Care Services

A number of advantages of unicondylar arthroplasty (UKA) over total knee arthroplasty in patients presenting osteoarthritis in only a single compartment have been identified in the literature. However, accurate implant positioning and alignment targets, which have been shown to significantly affect outcomes, are routinely missed by conventional techniques. Computer Assisted Orthopaedic Surgery (CAOS) has demonstrated its ability to improve implant accuracy, reducing outliers. Despite this, existing commercial systems have seen extremely limited adoption. Survey indicates the bulk, cost, and complexity of existing systems as inhibitive characteristics. We present a concept system based upon small scale head mounted tracking and augmented reality guidance intended to mitigate these factors. A visible-spectrum stereoscopic system, able to track multiple fiducial markers to 6DoF via photogrammetry and perform semi-active speed constrained resection, was combined with a head mounted display, to provide a video-see-through augmented reality system. The accuracy of this system was investigated by probing 180 points upon a 110×110×50 mm known geometry and performing controlled resection upon a 60×60×15 mm bone phantom guided by an overlaid augmented resection guide that updated in real-time. The system produced an RMS probing accuracy and precision of 0.55±0.04 and 0.10±0.01 mm, respectively. Controlled resection resulted in an absolute resection error of 0.34±0.04 mm with a general trend of over-resection of 0.10±0.07 mm. The system was able to achieve the sub-millimetre accuracy considered necessary to successfully position unicondylar knee implants. Several refinements of the system, such as pose filtering, are expected to increase the functional volume over which this accuracy is obtained. The presented system improves upon several objections to existing commercial CAOS UKA systems, and shows great potential both within surgery itself and its training. Furthermore, it is suggested the system could be readily extended to additional orthopaedic procedures requiring accurate and intuitive guidance

Difficulties arise when counselling younger patients on the long-term sequelae of a minor knee chondral defect. This study assesses the natural history of patients with grade 2 Outerbridge chondral injuries of the medial femoral condyle at arthroscopy. We reviewed all arthroscopies performed by one surgeon over 12 years with Outerbridge grade 2 chondral defects. Patients aged 30 to 59 were included. Meniscal injuries found were treated with partial menisectomy. All patients had five-year follow up minimum. Primary outcome measure was further interventions of total or unicondylar arthroplasty or high tibial osteotomy. We analysed 3,344 arthroscopies. Average follow up was 10 years (Range 5–17 years). A total of 357 patients met inclusion criteria of which 86 had isolated medial femoral condyle disease. Average age was 50 at the time of arthroscopy. Average BMI at surgery was 31.7 and average chondral defect area was 450 mm. 2. Isolated MFC chondral disease had a 10.5% intervention rate. Intervention occurred at a mean of 8.5 years post primary arthroscopy. In young patients Outerbridge II chondral injuries affecting ≥2 compartments have a high rate of further intervention within a decade. This information is crucial in counselling young patients on long-term sequelae of benign chondral lesions

The first proposal of high tibial osteotomy to align a varus knee caused by osteoarthritis was ascribed to Steindler in the 1940. The technique was followed by many surgeons because it re-established the load equilibrium in the medial and lateral compartment, reduced the progression of the osteoarthritis and improved the clinical symptoms. However, as a result of the quick spread of total knee replacement and unicondylar arthroplasty this corrective operation was forgotten. In recent years osteotomies were resumed for two main reasons: (a) the increased diagnosis of knee osteoarthritis in patients of middle age; and (b) the improvement of the technique and improvement of long-term results. The authors analysed the literature regarding the main techniques utilised in the correction of the axial and torsional deformities of osteoarthritic knee (linear or cuneiform osteotomies). The results of these various methods are similar. This could be due to the importance of common biological effects (early and late) related to the mechanical effect however it is obtained. In conclusion, the authors suggest that osteotomy must be resumed and applied with revised indications (patients in so-called middle age and unicondylar osteoarthritic knee)

Purpose. To examine how patients viewed the outcome of their joint replacement at least one year post surgery. Emphasis was placed on investigating the relative influence of ongoing pain and functional limitation on patient satisfaction. Method. Questionnaire based assessment of the Oxford Knee Score (OKS), patient satisfaction, and need for reoperation in a group of 10,000 patients who had undergone primary unilateral knee replacement between April and December 2003. Questionnaires were linked to the NJR database to provide data on background demographics, clinical parameters and intraoperative surgical information for each patient. Data was analysed to investigate the relationship between the OKS, satisfaction rate and the background factors. Multivariable logistic regression was performed to establish which factors influenced patient satisfaction. Results. 87.4% patients returned questionnaires. Overall 81.8% indicated they were satisfied with their knee replacement, with 7.0% unsatisfied and 11.2% unsure. The mean OKS varied dependent upon patients' satisfaction (satisfied=22.0, unsatisfied=41.7, unsure=35.2). These differences were statistically significant (p<0.001). Regression modelling showed that patients with higher scores relating to the pain and function elements of the OKS had lower levels of satisfaction (p<0.001) and that ongoing pain was a stronger predictor of lower levels of satisfaction. Other predictors of lower levels of satisfaction included female gender (p<0.05), a primary diagnosis of osteoarthritis (p=0.02) and unicondylar replacement (p=0.002). Differences in satisfaction rate were also observed dependent upon age and ASA grade. 609 patients (7.4%) had undergone further surgery and 1476 patients (17.9%) indicated another procedure was planned. Both the OKS and satisfaction rates were significantly better in patients who had not suffered complications. Conclusion. This study highlights a number of clinically important factors that influence patient satisfaction at one year following TKR. These should act as a benchmark of UK practice and be a baseline for peer comparison between institutions

Introduction. Kneeling ability is better in unicompartmental than total knee arthroplasty. There is also an impression that mobile bearing knees achieve better functional outcome than their fixed bearing cousins in unicompartmental and to a lesser extent total joint arthroplasty. In the UK, the market leading unicompartmental replacement is mobile bearing. Aim. To analyse kneeling ability after total and unicompartmental knee replacement using mobile and fixed bearing inserts. Methods. In our department there are two prospective randomised studies (fixed versus mobile) in this area. For total knee arthroplasty, 207 TKR patients receiving the same prosthesis (Rotaglide, Corin, UK) were randomised into mobile bearing (102 patients, mean age of 53 years) or fixed bearing (105 patients, mean age of 55 years). Regarding unicondylar knees, data was collected on 352 UKR patients who received the same implant (Uniglide - previously known as AMC - Corin, UK). Within this group there was a randomised controlled trial of fixed v mobile bearings: 52 patients (mean age 62 years) had a mobile insert and 57 (mean age 65 yrs) had a fixed insert. Data was also collected on patients undergoing fixed bearing lateral unicondylar replacement (Uniglide). All patients completed the Oxford Knee Questionnaire preoperatively, 1 year and 2 years postoperatively, (where 0 = bad and 48 = good). There kneeling ability (question 7) and total Oxford scores were analysed. We are currently collecting objective data on post-operative kneeling ability with force plate analysis and subjective anterior knee-specific scoring systems. Results. Subjective kneeling ability: Oxford Knee Score Question 7 as range 0-4, where 4 = good. Conclusion. Both fixed and mobile UKR and TKR have good outcome. No group produced good kneeling ability, but there was a modest improvement in all groups from the preoperative kneeling scores. Fixed bearing knee replacement showed better outcome than mobile bearing knees, in both UKR and TKR groups

Background: In a recent publication from the National Joint Registry it was suggested that prosthesis type influenced patient satisfaction at one year following knee arthroplasty. In this report Unicondylar Replacement (UKR) was associated with lower levels of patient satisfaction when compared to cemented TKR. The unicondylar group did however have a significantly lower Oxford Knee Score (OKS) than the TKR group and this occurred irrespective of patient age. A common perception is that UKR is only offered to patients with lesser disease, with a decreased clinical profile. This may explain their higher levels of dissatisfaction as the overall change in their OKS from pre to post operation would be relatively smaller than for TKR. Aim: We hypothesised that patients listed for UKR have less severe disease and therefore a lower preoperative OKS when compared to TKR. Methods: After sample size calculation we retrospectively analysed 76 patients who underwent either UKR or TKR under the care of a single surgeon. OKS was recorded at a dedicated pre-assessment clinic. The decision to offer UKR was based on clinical and radiological criteria as outlined by the Oxford group. Results: There were 38 patients in either group. The mean pre-operative OKS was 39.5 (26–56, SD 7.6) in the UKR group and 41.6 (31–51, SD 5.7) in the TKR group. There was no statistical difference between these two groups (p=0.18). Discussion: Patients listed for knee replacement have significant pain and functional impairment. In our population those suitable for UKR have similarly severe symptoms to those who do not meet the criteria for UKR and are only eligible for TKR. It remains unclear why patients undergoing UKR should be less satisfied when they have better post operative patient reported outcome scores. It emphasizes the need for careful patient selection and counselling in patient undergoing UKR

Introduction: With the growing number of primary knee arthroplasties, the number of revision operations is also increasing. The large number of unicondylar replacements carried out in the 1980’s, due to lack of modern total condylar implants, grant the revision techniques an outstanding significance in Hungary. One of the main issues of modern revision techniques is the management of bone defects, which can be solved by different methods documented in literature. Aim of study: The aim of our study was to investigate the success and feasibility of the various defect management techniques by evaluating the results of revision knee prosthetic surgeries carried out at our clinic. Patients and methods: Femoral and tibial bone defects had to be solved with revision surgeries in 35 cases, all performed due to aseptic loosening of uni- and total condylar prostheses implanted earlier. For filling of bone defects, metal augmentation of the prostheses was applied in 9 cases, allografts from bone bank were used in 11 cases, own cancellous bone was applied in 20 cases. Results were prospectively analysed with the help of the knee society rating system, with an average follow-up of two and a half years. Results: Revision interventions were successful in 34 cases, detailed results are revealed in the presentation, complemented with case presentations. In a single case, repeated intervention surgery is indicated due to disorganisation of the structural allograft and the resulting loosening of the tibial component. Conclusion: The success of the various bone replacement techniques, completed with adequate indication could be proven in all cases. The unsuccessful case proved that allograft incorporation should be supported by appropriate stem augmentation of the tibial component. In order to perform successful revision knee arthroplasty, we consider it fundamentally important to have a wide variety of allografts from bone bank and a modern knee prostheses system application already during primary implantations

Purpose: To examine how patients viewed the outcome of their joint replacement at least one year post surgery. Emphasis was placed on investigating the relative influence of ongoing pain and functional limitation on patient satisfaction. Method: Questionnaire based assessment of the Oxford Knee Score (OKS), patient satisfaction, and need for reoperation in a group of 10,000 patients who had undergone primary unilateral knee replacement between April and December 2003. Questionnaires were linked to the NJR database to provide data on background demographics, clinical parameters and intraoperative surgical information for each patient. Data was analysed to investigate the relationship between the OKS, satisfaction rate and the background factors. Multivariable logistic regression was performed to establish which factors influenced patient satisfaction. Results: 87.4% patients returned questionnaires. Overall 81.8% indicated they were satisfied with their knee replacement, with 7.0% unsatisfied and 11.2% unsure. The mean OKS varied dependent upon patients’ satisfaction (satisfied=22.04 (S.D 7.87), unsatisfied=41.70 (S.D 8.32), unsure=35.17 (S.D 8.24)). These differences were statistically significant (p< 0.001). Regression modelling showed that patients with higher scores relating to the pain and function elements of the OKS had lower levels of satisfaction (p< 0.001) and that ongoing pain was a stronger predictor of lower levels of satisfaction. Other predictors of lower levels of satisfaction included female gender (p< 0.05), a primary diagnosis of osteoarthritis (p=0.02) and unicondylar replacement (p=0.002). Differences in satisfaction rate were also observed dependent upon age and ASA grade. 609 patients (7.4%) had undergone further surgery and 1476 patients (17.9%) indicated another procedure was planned. Both the OKS and satisfaction rates were significantly better in patients who had not suffered complications. Conclusion: This study highlights a number of clinically important factors that influence patient satisfaction following knee replacement. This information could be used when planning surgery to counsel patients and help form realistic expectations of the anticipated postoperative result

Introduction. Bicompartmental osteoarthritis involving the medial tibiofemoral and the patellofemoral compartments is often treated with total knee replacement. Improved implants and surgical techniques have led to renewed interest in bicompartmental arthroplasty. This study evaluates the radiographic and early clinical results of bicompartmental arthroplasty with separate unlinked components implanted with the assistance of a robotic surgical arm. In addition, we examine the amount of bone resected using unlinked bicompartmental components compared to total knee replacement. Finally, a retrospective review of total knee cases examines the applicability of this early intervention procedure. Methods. 97 patients received simultaneous but geometrically separate medial tibiofemoral and patellofemoral arthroplasties with implants specifically designed to take advantage of a new bone and tissue sparing implantation technique using haptic robotics. These patients came from four surgeons at four different hospitals. The average follow-up was 9 months. Pre- and post-operative radiographs were taken. ROM, KSS and WOMAC scores were recorded. The patients had an average age of 67 yrs (range: 45-95), BMI of 29 ± 4kg/m. 2. 47% of the patients were male. We retrospectively reviewed pre and post operative notes from 406 consecutive TKA patients from a single surgeon. Intraoperative data included the integrity of the three compartments and the ACL. Results. At only six weeks follow-up, patients recovered their pre-operative ROM (p=0.37). Knee Society Knee scores (knee and function) and WOMAC scores (pain, function and total) significantly improved from pre-operative values at every follow-up of 6 weeks, 6 months and 1 year (p<0.05). Radiographically, there was no evidence of loosening, wear or progression of OA. There were also no perioperative complications. Using computer simulation, the amount of bone removed using bicompartmental arthroplasty compared to traditional TKA was predicted. Total bone removed on the femur and the tibia using a standard TKA implant is 3.5 times the bone removed using a bicompartmental onlay implant and 4 times the bone removed when using a bicompartmental inlay implant. In the review of 406 TKA cases, the ACL was intact in 66% of these cases. Based on these data alone, 16% of these TKA patients were indicated for a unicondylar arthroplasty, 12% medial UKA, 3% lateral UKA and 1% PFA. In addition, 31% were indicated for bicompartmental arthroplasty with 4% bicondylar (medial and lateral UKA), 6% lateral UKA and PFA and 21% medial UKA and PFA. While these data don't yet account for fixed versus flexible deformities, excessive osteophytes or other contraindications, it seems clear that the disease often treated with a TKA does not actually involve all three compartments. Conclusions. Modular bicompartmental arthroplasty is an effective method for treating arthritis of the knee restricted to the medial and patellofemoral compartments. Early results using contemporary prostheses are encouraging and should prompt further mid- and long-term study. Robotic assistance of bicompartmental arthroplasty has shown good early clinical and radiographic success. In addition, bicompartmental arthroplasty removes significantly less bone than total knee arthroplasty. Also, data indicates that may total knee patients have healthy cruciates and disease in only two of the three compartments, indicating that TKA is an overtreatment of earlier stage osteoarthritis. Longer term studies will determine the clinical significance of preserving healthy cartilage and ligaments routinely resected with traditional tricompartmental TKA

Aims

The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA).

Minimal Invasive Surgery (MIS) in total knee arthroplasty (TKA) has gained much attention in the scientific community and the public in the last few years. There still exists confusion in the related terminology and different surgical techniques are recommended. Cost effectiveness and risk/benefit analysis are not available at the moment. There still remains controversy whether these new techniques represent only a modern trend or the future of TKA. MIS Unicondylar replacement has shown significant faster rehabilitation but the same reproducible radiographic and clinical results compared with the conventional open technique. In Oct 2003 we have started using MIS TKA in our hospital. After a significant learning curve the decision was made to do only MIS TKA from Nov. 2004 up to now. More than 300 cases were performed. Only few definite data are available at this stage. In 20% of the patients we performed the so called quad sparing (QS) technique. This offers a less invasive but very demanding and time consuming approach, where most of the surgery has to be performed from the side using complete new side cutting instruments. In the majority of our patients (80%) we performed a modified mini midvastus (MMI) approach, using standard 4 in 1 front cutting instruments. Electromagnetic navigation (EM) might be a helpful tool for MIS surgery in TKA. We have limited experience with this new EM navigation system in combination with the new MIS TKA surgical techniques. In a pilot study with two groups of patients the direct comparison between QS and MMI was evaluated. Clinical evaluation was performed by two scores (KSS and WOMAC) and five additional functional tests including straight leg raising, active motion, raising a chair, stair climbing and functional gait analysis. Testing was performed pre-op and at 1, 6 and 12 weeks post-op. Patients and investigators were blinded to the surgical technique (either QS or MMI). The average OR time was 92 min (70 to 130) for MMI and 110 (85 to 165) for QS respectively. There were no complications in the MMI and 1 (wound healing) in the QS group. There were no differences in the different scores and in the functional tests between the groups at any time. There is still controversy in the benefit-risk analysis for the different minimal invasive techniques. In our hospital the MIS future for TKA has already started. Patients’ satisfaction and significant earlier rehabilitation are the key advantages of these new surgical techniques. The much easier MMI technique is now the standard. Only in selected cases the more demanding QS technique is performed. According to the learning curve these new MIS techniques are for specialized surgeons only and require additional training programmes. Despite these facts, we do believe that MIS is the future of TKA surgery