Publication of normal and expected outcome scores is necessary to provide a benchmark for auditing purposes following arthroplasty surgery. We have used the Oxford knee score to monitor the progress of knee replacements undertaken since 1995, the start of our review programme. 4847 Oxford assessments were analysed over an 8 year follow-up period.

The mean pre-operative Oxford knee score was 39.2, all post-operative reviews showed a significant improvement. Patients with a BMI > 40, and the under 50 age group showed early deterioration in outcome scores, returning to pre-operative levels by 5 and 7 years respectively. There was no significant difference in outcome between surgeons performing < 20 knee replacements a year and those performing > 100 / year.

The age of the patient at the time of surgery and the pre-operative body habitus have been identified as factors affecting long term outcome of total knee replacement surgery. Awareness of these factors may assist surgeons in advising patients of their expected outcomes following surgery.

The Oxford Knee Score (OKS) is a valid and reliable self-administered patient questionnaire that enables assessment of the outcome following total knee replacement (TKR). There is as yet no literature on the behavioral trends of the OKS over time. Our aim is to present a retrospective audit of the OKS for patients who have undergone TKR during the past ten years.

We retrospectively analysed 3276 OKS of patients who had a primary TKR and had been registered as part of a multi-surgeon, outcome-monitoring program at St. Helier hospital. The OKS was gathered pre-operatively and post-operatively by means of postal questionnaires at annual intervals. Patients were grouped as per their age at operation into four groups: 60, 61-70, 71- 80 and >80. A cross-sectional analysis of OKS at different time points was performed.

The numbers of OKS available for analysis were 504 pre-operatively, 589 at one-year, 512 at two-year and gradually decreasing numbers with 87 knees ten-year post-operatively. There was as expected a significant decrease (improvement) of the OKS between pre-operative and one-year post-operative period and then reached a plateau. Beyond eight years, there is a gradual rise in the score (deterioration). The younger patients (60) showed a significant increase in their average OKS between one and five-years post-operatively. However beyond five years, they followed the trend of their older counterparts. When the twelve questions in the OKS were analysed, certain components revealed greater improvement (e.g. description of knee pain and limping) than others (e.g. night pain).

The OKS is seen to plateau a year after TKR. According to the OKS the outcome of the TKR is not as good in the younger age group as compared to the older age group. Further investigation is required to ascertain the cause of this observed difference.

Aims. To assess the incidence of radiological lateral osteoarthritis (OA) at 15 years after medial unicompartmental knee arthroplasty (UKA) and assess the relationship of lateral OA with symptoms and patient characteristics. Methods. Cemented Phase 3 medial Oxford UKA implanted by two surgeons since 1998 for the recommended indications were prospectively followed. A 15-year cumulative revision rate for lateral OA of 5% for this series was previously reported. A total of 163 unrevised knees with 15-year (SD 1) anterior-posterior knee radiographs were studied. Lateral joint space width (JSW. L. ) was measured and severity of lateral OA was classified as: nil/mild, moderate, and severe. Preoperative and 15-year Oxford Knee Scores (OKS) and American Knee Society Scores were determined. The effect of age, sex, BMI, and intraoperative findings was analyzed. Statistical analysis included one-way analysis of variance and Kruskal-Wallis H test, with significance set at 5%. Results. The mean age was 80.6 years (SD 8.3), with 84 females and 79 males. The mean JSW. L. was 5.6 mm (SD 1.4), and was not significantly related to age, sex, or intraoperative findings. Those with BMI > 40 kg/m. 2. had a smaller JSW. L. than those with a ‘normal’ BMI (p = 0.039). The incidence of severe and moderate lateral OA were both 4.9%. Overall, 2/142 (1.4%) of those with nil/mild lateral OA, 1/8 (13%) with moderate, and 2/8 (25%) with severe subsequently had a revision. Those with severe (mean OKS 35.6 (SD 9.3)) and moderate OA (mean OKS 35.8 (SD 10.5)) tended to have worse outcome scores than those with nil/mild (mean OKS 39.5 (SD 9.2)) but the difference was only significant for OKS-Function (p = 0.044). Conclusion. This study showed that the rate of having severe or moderate radiological lateral OA at 15 years after medial UKA was low (both 4.9%). Although patients with severe or moderate lateral OA had a lower OKS than those with nil/mild OA, their mean scores (OKS 36) would be classified as good. Cite this article: Bone Jt Open 2023;4(3):210–218

Aims. While residual fixed flexion deformity (FFD) in unicompartmental knee arthroplasty (UKA) has been associated with worse functional outcomes, limited evidence exists regarding FFD changes. The objective of this study was to quantify FFD changes in patients with medial unicompartmental knee arthritis undergoing UKA, and investigate any correlation with clinical outcomes. Methods. This study included 136 patients undergoing robotic arm-assisted medial UKA between January 2018 and December 2022. The study included 75 males (55.1%) and 61 (44.9%) females, with a mean age of 67.1 years (45 to 90). Patients were divided into three study groups based on the degree of preoperative FFD: ≤ 5°, 5° to ≤ 10°, and > 10°. Intraoperative optical motion capture technology was used to assess pre- and postoperative FFD. Clinical FFD was measured pre- and postoperatively at six weeks and one year following surgery. Preoperative and one-year postoperative Oxford Knee Scores (OKS) were collected. Results. Overall, the median preoperative navigated (NAV) FFD measured 6.0° (IQR 3.1 to 8), while the median postoperative NAV FFD was 3.0° (IQR 1° to 4.4°), representing a mean correction of 49.2%. The median preoperative clinical FFD was 5° (IQR 0° to 9.75°) for the entire cohort, which decreased to 3.0° (IQR 0° to 5°) and 2° (IQR 0° to 3°) at six weeks and one year postoperatively, respectively. A statistically significant improvement in PROMs compared with baseline was evident in all groups (p < 0.001). Regression analyses showed that participants who experienced a larger FFD correction, showed greater improvement in PROMs (β = 0.609, p = 0.049; 95% CI 0.002 to 1.216). Conclusion. This study found that UKA was associated with an approximately 50% improvement in preoperative FFD across all three examined groups. Participants with greater correction of FFD also demonstrated larger OKS gains. These findings could prove a useful augment to clinical decision-making regarding candidacy for UKA and anticipated improvements in FFD

Aims. To investigate health-related quality of life (HRQoL) of older adults (aged ≥ 60 years) after tibial plateau fracture (TPF) compared to preinjury and population matched values, and what aspects of treatment were most important to patients. Methods. We undertook a retrospective, case-control study of 67 patients at mean 3.5 years (SD 1.3; 1.3 to 6.1) after TPF (47 patients underwent fixation, and 20 nonoperative management). Patients completed EuroQol five-dimension three-level (EQ-5D-3L) questionnaire, Lower Limb Function Scale (LEFS), and Oxford Knee Scores (OKS) for current and recalled prefracture status. Propensity score matching for age, sex, and deprivation in a 1:5 ratio was performed using patient level data from the Health Survey for England to obtain a control group for HRQoL comparison. The primary outcome was the difference in actual (TPF cohort) and expected (matched control) EQ-5D-3L score after TPF. Results. TPF patients had a significantly worse EQ-5D-3L utility (mean difference (MD) 0.09, 95% confidence interval (CI) 0.00 to 0.16; p < 0.001) following their injury compared to matched controls, and had a significant deterioration (MD 0.140, 95% CI 0 to 0.309; p < 0.001) relative to their preoperative status. TPF patients had significantly greater pre-fracture EQ-5D-3L scores compared to controls (p = 0.003), specifically in mobility and pain/discomfort domains. A decline in EQ-5D-3L greater than the minimal important change of 0.105 was present in 36/67 TPF patients (53.7%). Following TPF, OKS (MD -7; interquartile range (IQR) -1 to -15) and LEFS (MD -10; IQR -2 to -26) declined significantly (p < 0.001) from pre-fracture levels. Of the 12 elements of fracture care assessed, the most important to patients were getting back to their own home, having a stable knee, and returning to normal function. Conclusion. TPFs in older adults were associated with a clinically significant deterioration in HRQoL compared to preinjury level and age, sex, and deprivation matched controls for both undisplaced fractures managed nonoperatively and displaced or unstable fractures managed with internal fixation. Cite this article: Bone Jt Open 2023;4(4):273–282

Aims

The metabolic equivalent of task (MET) score examines patient performance in relation to energy expenditure before and after knee arthroplasty. This study assesses its use in a knee arthroplasty population in comparison with the widely used Oxford Knee Score (OKS) and EuroQol five-dimension index (EQ-5D), which are reported to be limited by ceiling effects.

Aims

Treatment of end-stage anteromedial osteoarthritis (AMOA) of the knee is commonly approached using one of two surgical strategies: medial unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA). In this study we aim to investigate if there is any difference in outcome for patients undergoing UKA or TKA, when treated by high-volume surgeons, in high-volume centres, using two different clinical guidelines. The two strategies are ‘UKA whenever possible’ vs TKA for all patients with AMOA.

Aims

Bi-unicondylar arthroplasty (Bi-UKA) is a bone and anterior cruciate ligament (ACL)-preserving alternative to total knee arthroplasty (TKA) when the patellofemoral joint is preserved. The aim of this study is to investigate the clinical outcomes and biomechanics of Bi-UKA.

Aims

Periprosthetic joint infection (PJI) occurs in approximately 1% to 2% of total knee arthroplasties (TKA) presenting multiple challenges, such as difficulty in diagnosis, technical complexity, and financial costs. Two-stage exchange is the gold standard for treating PJI but emerging evidence suggests 'two-in-one' single-stage revision as an alternative, delivering comparable outcomes, reduced morbidity, and cost-effectiveness. This study investigates five-year results of modified single-stage revision for treatment of PJI following TKA with bone loss.

Aims

Simultaneous bilateral total knee arthroplasty (TKA) has been used due to its financial advantages, overall resource usage, and convenience for the patient. The training model where a trainee performs the first TKA, followed by the trainer surgeon performing the second TKA, is a unique model to our institution. This study aims to analyze the functional and clinical outcomes of bilateral simultaneous TKA when performed by a trainee or a supervising surgeon, and also to assess these outcomes based on which side was done by the trainee or by the surgeon.

Aims. It has been hypothesized that a unicompartmental knee arthroplasty (UKA) is more likely to be revised than a total knee arthroplasty (TKA) because conversion surgery to a primary TKA is a less complicated procedure. The purpose of this study was to determine if there is a lower threshold for revising a UKA compared with TKA based on Oxford Knee Scores (OKSs) and range of movement (ROM) at the time of revision. Methods. We retrospectively reviewed 619 aseptic revision cases performed between December 1998 and October 2018. This included 138 UKAs that underwent conversion to TKA and 481 initial TKA revisions. Age, body mass index (BMI), time in situ, OKS, and ROM were available for all patients. Results. There were no differences between the two groups based on demographics or time to revision. The top reasons for aseptic TKA revision were loosening in 212 (44%), instability in 88 (18%), and wear in 69 (14%). UKA revision diagnoses were primarily for loosening in 50 (36%), progression of osteoarthritis (OA) in 50 (36%), and wear in 17 (12%). Out of a maximum 48 points, the mean OKS of the UKAs before revision was 23 (SD 9.3), which was significantly higher than the TKAs at 19.2 (SD 9.8; p < 0.001). UKA patients scored statistically better on nine of the 12 individual OKS questions. The UKA cases also had a larger pre-revision mean ROM (114°, SD 14.3°) than TKAs (98°, SD 25°) ; p < 0.001). Conclusion. At revision, the mean UKA OKSs and ROM were significantly better than those of TKA cases. This study suggests that at our institution there is a difference in preoperative OKS between UKA and TKA at the time of revision, demonstrating a revision bias. Cite this article: Bone Joint J 2020;102-B(6 Supple A):91–95

Abstract. Introduction. Anecdotal reports suggest some cementless Oxford Unicompartmental Knee Replacements (OUKRs) have painful early subsidence of the tibial component with valgus rotation and/or posterior tilting. The incidence of subsidence and its association with pain is poorly understood. This radiographic study aimed to evaluate the incidence of tibial subsidence and five-year patient reported outcome measures (PROMs) of a cementless OUKR cohort. Methodology. Cementless OUKRs from a high-volume centre with acceptable post-operative and five-year radiographs were included. Subsidence was determined by measuring the angle of the tibial tray/tibial axis angle and distance between the tibial tray axis and fibula head on anteroposterior and lateral radiographs using a custom MATLAB program. Analysis of 5-year PROMs assessed the relationship between subsidence and pain. Radiographs indicating tibial subsidence were validated by two observers. Results. Radiographs of 94 cementless OUKRs were analysed of which five tibial components had subsided (incidence=5%) with an average of 1.92° varus rotation and 2.97° posterior tilt. Subsidence appeared to occur within the first post-operative year with all tibial components fixed securely at 5 years. Two subsiders had moderate pain (ICOAP=20.5,15.9, AKSS Pain=20,45) and lower Oxford Knee Scores (OKS=26,31) compared to the cohort means (ICOAP=3.91, AKSS Pain=45.9, OKS = 43.6). These two subsiders had BMIs greater than 30. Conclusion. This study found 5% of cementless OUKRs in the cohort underwent tibial subsidence. Subsidence with moderate pain occurred in 2% of cases, and pain may be associated with obesity. A larger study is needed to study subsidence in greater detail

Robotic assistance in knee arthroplasty has become increasingly popular due to improved accuracy of prosthetic implantation. However, literature on the mid-term outcomes is limited especially that of hand-held robotic-assisted devices. We present one of the longest follow-up series to date using this novel technology and discuss the learning curve for introducing robotic technology into our practice. The purpose of this single-surgeon study is to evaluate the survival, patient-reported outcomes and learning curve for handheld boundary-controlled robotic-assisted unicompartmental knee arthroplasties (HBRUKAs) at our hospital. This retrospective study evaluates 100 cases (94 Medial, 6 Lateral) performed by a single surgeon between October 2012 and July 2018. 52% were males, mean age was 64.5y (range 47.3y-85.2y) and mean BMI was 31.3 (range 21.8–43). Both inlay (40%) and onlay (60%) designs were implanted. Patients were followed up routinely at 1 and 5 years with Oxford Knee Scores (OKS) recorded. The learning curve was determined by tourniquet times. At a mean follow-up of 4.3 years (range 1.6y–7.3y), survivorship was 97%. There were three revisions: One case of aseptic loosening (1.5y), one case of deep-infection (3.8y) and one case of contralateral compartment osteoarthritis progression (5y). Mean 5-year OKS was 39.8. A 14.3% reduction in mean tourniquet times between the first 25 cases (105.5minutes) and subsequent cases (90.4minutes) was seen. This single-surgeon study showed good survivorship and patient-reported outcomes for HBRUKAs at our hospital. A learning curve of approximately 25 cases was shown, with significant decreases in tourniquet times with respect to increased surgeon experience

Abstract. Introduction. Little is known about employment following revision total knee arthroplasty (RTKA). This study aims to describe factors associated with returning to employment in patients of working age who underwent RTKA surgery. Methodology. We performed a retrospective assessment of all patients aged ≤65 who underwent RTKA at our NHS institution between 2006 and 2020. All indications and revision procedures were included. Pre-operative demographics, indication for surgery and Oxford Knee Scores (OKS) were recorded. Postal questionnaires were sent to patients including patient reported outcome measures and departmental questionnaire asking patients about employment status pre- and post-operatively. Results. 132 procedures were performed in 113 patients. Median follow up was 5.5 years (2.4–9.0). Mean age was 58 (5.8) and 50% (57) were male. 62 patients undergoing 74 procedures responded to postal questionnaires and were included in the study. 53% (33) were employed prior to surgery and 61% (38) returned to work at a median of 12 weeks (3–150). Of the 24 who did not return to work, 7 reported intending to return to work. Those patients who returned to work had increased pre-operative OKS (16.9 vs 13.6) and mean improvement (16.5 vs 12.4). Conclusion. This study is limited by small numbers and its observational nature. In this population the majority of patients who wished to return to work after RTKA were able to do so. This provides some reassurance when counselling patients. Prospective studies to better understand the factors that predict return to work will be important with increasing demands from surgery

Abstract. Introduction. Augmentation of meniscus repairs with fibrin clot may enhance the healing capacity. Pulling the clot into the tear with a suture ensures that it stays in position. This paper aims to assess the outcome of this technique. Methods. 52 patients over 4 years undergoing suture repair of a meniscus tear with blood clot augmentation were collected from a prospective database. Follow up included outcome scores and a questionnaire. Failure was defined as pain or further surgery secondary to meniscal pathology. Results. There were 32 males and 20 females, mean age of 35 (14–70). The medial meniscus was repaired in 32 knees and the lateral in 20. Complete radial tears were the most common type. Only 2% of tears were in the red-red zone. Follow-up ranged from 12 months to 7 years. Only 1 patient is known to have come to subsequent arthroscopy. Lysholm scores improved from 53.97 (SD 18.14) to 92.08 (SD 8.97), Oxford Knee Scores from 29.84 (SD 9.65) to 45.79 (SD 2.66), KOOS pain scores from 61.49 (SD 22.76) to 93.54 (SD 8.06) and Tegner scores from 4.56 (SD 3.35) to 6.05 (SD 2.41). Conclusions. Pulling a fibrin blood clot into a meniscus tear with a suture ensures that the clot remains in place while the meniscus is repaired. Patients have shown excellent outcomes with 98% survivorship at 45 months. This is a reliable technique for augmenting meniscus repairs especially for tears which otherwise may not have been repaired

Contemporary indications for unicompartmental knee replacement (UKR) include bone on bone radiographic changes in the medial compartment with relatively preserved lateral and patellofemoral compartments. The role of MRI in identifying candidates for UKR is commonplace. The aim of this study was to assess the relationship between radiographic and MRI pre-operative grade and outcome following UKR. A retrospective analysis of medial UKR patients from 2017 to 2021. Inclusion criteria were medial UKR for osteoarthritis with pre-operative and post-operative Oxford Knee Scores (OKS), pre-operative radiographs and MRI. 89 patients were included. Whilst all patients had grade 4 ICRS scores on MRI, 36/89 patients had grade 3 KL radiographic scores in the medial compartment, 50/89 had grade 4 KL scores on the medial compartment. Grade 3 KL with grade 4 IRCS medial compartment patients had a mean OKS change of 17.22 (Sd 9.190) meanwhile Grade 4 KL had a mean change of 17.54 (SD 9.001), with no statistical difference in the OKS change score following UKR between these two groups (p=0.873). Medial bone oedema was present in all but one patient. Whilst lateral compartment MRI ICRS scores ranged from 1 to 4 there was no association with MRI score of the lateral compartment and subsequent change in oxford score (P value 0.458). Patellofemoral Compartment (PFC) MRI ICRS ranged from 0 to 4. There was no association between PFC ICRS score and subsequent change in oxford knee score (P value .276). Radiographs may under report severity of some medial sided knee osteoarthritis. We conclude that in patients with grade 3 KL score that would normally not be considered for UKR, pre-operative MRI might identify grade 4 ICRS scores and this subset of patients have equivalent outcomes to patients with radiographic Grade 4 KL medial compartment osteoarthritis

Patient reported outcome measures (PROMs) after total knee arthroplasty (TKA) are typically used to assess longitudinal change in pain and function after total knee arthroplasty (TKA). The Patient's Knee Implant Performance (PKIP) score was developed to evaluate outcomes more broadly including function, stability, confidence, and satisfaction. Although validated in patients having a primary TKA, the PKIP has not been evaluated as an outcome measure for patients having revision TKA. This study examined patient outcomes at one year following primary and revision TKA measured using the PKIP, compared to Oxford Knee Scores. A retrospective analysis of pre-operative and one-year post-operative outcomes was completed for 39 patients (21 female) who had primary (n=27) or revision (n=12) TKA with a single surgeon between 2017 and 2020. The mean age was 69.2±7.4 years, and mean weight 87.4± 5.1kg. The change over time and correlation between the self-reported outcome measures was evaluated. There was a significant improvement in the PKIP overall score at the 12-month follow-up (32± 13 v 69± 15, p= <0.001), with no significant difference between groups (3.3 points, p=0.50). Among the PKIP sub-scores, there was a significant improvement in knee confidence (3.5±2 vs 7.7±2; p<0.001), stability (3.4±2 vs 7.4±3; p<0.001) and satisfaction (2.5±1.7 vs 6.6±3, p<0.001). Between group differences in PKIP sub-scores one year after surgery were small and non-significant. For all patients, the OKS and PKIP scores were moderately correlated before surgery (r=0.64, p=<0.05), and at 1 year after surgery (r=0.61, p= <0.001). Significant improvements in knee confidence, stability, and satisfaction one year after TKA were identified from the PKIP responses, with no significant difference between primary and revision surgery. The moderate correlation with the OKS suggests these questionnaires measure difference constructs and may provide complementary outcome information in this patient cohort

Abstract. Introduction. In revision knee arthroplasty, rotating hinge implants (RHK) have been considered to result in higher complication rates and lower survivorship when compared to constrained condylar implants (CCK). The aims of this study were to compare patient reported outcome measures (PROMs), complication rates and survivorship of RHK and CCK used in revision arthroplasty at a single, high volume elective orthopaedic centre with previously validated bespoke database. Methodology. One hundred and eight patients who underwent revision knee arthroplasty with either CCK or RHK and matched our inclusion criteria were identified. EQ5D, Health State and Oxford Knee Scores were collected pre-operatively and at 1 year post-operatively. Complication data was collected at 6 weeks, 6 months, 1 year and 2 years post-operatively. NJR data was interrogated, in addition to our own database, to investigate implant survival. Results. There was no statistically significant difference between RHK and CCK in implant survival at two to twelve years of follow up. In addition, we observed no statistically significant difference in the PROMs scores and complication rates of the two implants. Conclusion. This study shows that both the RHK and CCK remain viable options in revision arthroplasty, the implant survival and complication rate were comparable. We recommend prospective randomised control trials with long-term follow up to further investigate the use of CCK and RHK implants in revision knee arthroplasty

Introduction. It has been hypothesized that a unicompartmental knee arthroplasty (UKA) is more likely to be revised than a total knee (TKA) because conversion surgery to a primary TKA is available. The purpose of this study was to determine if there is a lower threshold for UKA revisions compared to TKA revisions based on Oxford Knee Scores and range of motion (ROM). Methods. We retrospectively reviewed 636 aseptic revision cases performed between 1998 and 2018. This included 137 UKAs that underwent conversion to TKA and 499 TKA revisions. Pre-revision age, body mass index (BMI), time in situ, Oxford Knee Scores, and ROM were available for all patients. T-tests were performed to determine if significant differences existed between the two groups. The minimal clinically important difference (MCID) when comparing Oxford scores between cohorts has been reported as 5 points. Results. There were no differences between the two groups based on gender, BMI, age, or time to revision. The top three reasons for revision are different. TKR revision diagnoses were loosening 43%, instability 18% and wear 13%. UKA revision diagnoses are progression of OA 37%, loosening 36%, and wear 12%. All UKA were converted to TKA while there were 440 partial and 59 all component TKR revisions. Out of a maximum 48 points, the mean Oxford score of the UKAs before revision was 23±9.5, which was significantly higher than the TKAs at 19.3±9.7 (p<0.001). UKA patients scored statistically better on nine of the twelve Oxford questions with no difference in pain, walking, and sit to stand questions. Revised UKA had greater pre-revision ROM (1140) than TKR (990, p<0.001). Conclusion. The mean UKA Oxford scores prior to revision were significantly better than pre-revision TKA scores and better on 9 of 12 individual Oxford questions. However, the 3.7 point mean difference is less than the 5 point MCID for the Oxford Knee Score. This study suggests that at our institution there may not be a difference in patient reported Oxford preoperative scores between UKA and TKR revisions implying that we are not more likely to revise a UKA than a TKA. This is not surprising since our center does a high volume of UKA. We have also performed sub analyses comparing UKA revision scores to partial and both component TKA revision scores. For figures, tables, or references, please contact authors directly

Abstract. 20% of patients are severely dis-satisfied following total knee arthroplasty (TKA). Arthrofibrosis is a devastating complication preventing normal knee range of motion (ROM), severely impacting patient's daily living activities. A previous RCT demonstrated superiority of a high intensity stretching programme using a novel device the STAK tool compared with standard physiotherapy in TKA patients with arthrofibrosis. This study analyses the results when the previous “standard physiotherapy” group were subsequently treated with the STAK tool. Methods. 15 patients post TKA with severe arthrofibrosis and mean ROM 71° were recruited, (three cases had previously failed manipulation under anaesthetic (MUA). Patients received 8 weeks standard physiotherapy, then treatment with the STAK at home for 8 weeks. ROM, extension, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Oxford Knee Scores (OKS) were collected at various time-points. Results. Following standard physiotherapy there were small improvements in ROM (8°) (p<0.01), but no significant improvements in extension, OKS or WOMAC (p=0.39). Following the STAK treatment all outcomes significantly improved (p<0.01). STAK group; mean ROM (21° versus 8°, p < 0.001), extension 9° versus 2° (p < 0.01), WOMAC (18 points versus 3, p < 0.01), and OKS (8 points versus 4, p<0.01). No patients suffered any complications relating to the STAK. Conclusions. The STAK is effective in increasing ROM, extension and function, whilst reducing pain and stiffness. The device can be considered a cost-effective and valuable treatment following TKA. This is likely to increase the overall satisfaction rate and has potential to reduce the need for MUA