Preoperative Oxford Knee Score Research Articles

Socioeconomic status affects the Oxford knee score and Short-Form 12 score following total knee replacement

We assessed the effect of social deprivation upon the Oxford knee score (OKS), the Short-Form 12 (SF-12) and patient satisfaction after total knee replacement (TKR). An analysis of 966 patients undergoing primary TKR for symptomatic osteoarthritis (OA) was performed. Social deprivation was assessed using the Scottish Index of Multiple Deprivation. Those patients that were most deprived underwent surgery at an earlier age (p = 0.018), were more likely to be female (p = 0.046), to endure more comorbidities (p = 0.04) and to suffer worse pain and function according to the OKS (p < 0.001). In addition, deprivation was also associated with poor mental health (p = 0.002), which was assessed using the mental component (MCS) of the SF-12 score. Multivariable analysis was used to identify independent predictors of outcome at one year. Pre-operative OKS, SF-12 MCS, back pain, and four or more comorbidities were independent predictors of improvement in the OKS (all p < 0.001). Pre-operative OKS and improvement in the OKS were independent predictors of dissatisfaction (p = 0.003 and p < 0.001, respectively). Although improvement in the OKS and dissatisfaction after TKR were not significantly associated with social deprivation per se, factors more prevalent within the most deprived groups significantly diminished their improvement in OKS and increased their rate of dissatisfaction following TKR.

Early results of a domed tibia, mobile bearing lateral unicompartmental knee arthroplasty from an independent centre

AimThe aim of this study is to determine the short-term outcome of lateral unicompartmental knee arthroplasty (UKA) using a domed tibia, mobile bearing prosthesis. The primary outcome measure was revision due to bearing dislocation and the secondary measure was functional outcome. MethodsFrom 2005 to 2009, a total of 64 knees, in 58 patients, were identified as having the domed tibia, mobile bearing lateral UKA with a minimum 2-year follow-up. Forty-one females and 17 males with a mean age of 71years (range 44 to 92, median 72) were reviewed. The mean follow-up period was 38months (range 24 to 61, median 36). The primary outcome measure was re-operation and revision rate, particularly due to bearing dislocation. The secondary outcome assessed was a patient reported outcome measure (PROM) using the Oxford Knee Score (OKS) and compared using Student's Paired T-test. ResultsThere were four knees that underwent further surgery for any reason. Two patients required revision of the implant (3.1%). There were no cases of bearing dislocation in this series. The mean pre-operative OKS was 24 (range 9 to 36) and the mean post-operative score was 42 (range 23 to 48 p<0.0001). ConclusionThis study from an independent centre, reporting on the short-term results of the domed tibia, mobile bearing lateral UKA supports the safety and efficacy of the procedure as a treatment option in the patients with lateral compartment osteoarthritis (OA) of the knee. Level of evidenceThis is a level 4; case series study.

Does body mass index affect the outcome of unicompartmental knee replacement?

BackgroundObesity is considered to be a contraindication for unicompartmental knee replacement (UKR). The aim was to study the impact of BMI on failure rate and clinical outcome of the Oxford mobile bearing UKR. MethodTwo thousand four hundred and thirty-eight medial Oxford UKRs were studied prospectively and divided into groups: BMI<25 (n=378), BMI 25 to <30 (n=856), BMI 30 to <35 (n=712), BMI 35 to <40 (n=286), and BMI 40 to <45 (n=126) and BMI≥45 (n=80). ResultsThere was no significant difference in survival rate between groups. At a mean follow-up of 5years (range 1–12years) there was no significant difference in the Objective American Knee Society Score between groups. There was a significant (p<0.01) trend with the Oxford Knee Score (OKS) and Functional American Knee Society Scores decreasing with increasing BMI. As there was an opposite trend (p<0.01) in pre-operative OKS, the change in OKS increased with increasing BMI (p=0.048). The mean age at surgery was significantly (p<0.01) lower in patients with higher BMI. ConclusionsIncreasing BMI was not associated with an increasing failure rate. It was also not associated with a decreasing benefit from the operation. Therefore, a high BMI should not be considered a contra-indication to mobile bearing UKR. Level of evidenceIV

Special surgical technique for knee arthroplasty

BackgroundWe have not found any substantial reports on the effect and use of physiotherapy after knee replacement. Despite intense debate regarding whether new techniques for knee arthroplasty improve clinical outcomes over standard techniques, few prospective randomized trials addressing this debate are available in the literature. We have therefore designed the new technique to assess the overall safety and effectiveness of knee arthroplasty with the early outcomes. Patients gain good range of movement (ROM) without any physiotherapists' assistance using the new least invasive surgical technique. MethodsIn the follow-up study of 300 patients (68% females and 32% males with an age group range from 34 years to 94 years) had to undergo knee replacement surgery with the use of least invasive knee instruments, using new surgical technique. ResultsFollow-up duration is 2 years. Mean incision length was 3.5–4 inches. The mean pre-operative Oxford Knee Score (OKS) was 15.4 and that improved to 43.6 post-operatively after 1 year. Average range of movement was 110° after 18 days, 121° after 3 months and 131° at the end of 1 year. All cases operated with the new technique gained good range of knee movement post-operatively without any physiotherapist help or assistance. ConclusionThe advantages of the new technique over other conventional methods are smaller skin incision, minimal joint exposure, minimal blood loss, no use of diathermy, which reduces the chances of infection & shorter hospital stay to average less than 3 days. Patients can stand within 4 h of surgery and walk within 4–12 h of surgery. The new technique has helped the patients to recover early with good range of knee movements without the help of physiotherapist. However, patients are advised to do routine knee movements, to avoid complications like deep vein thrombosis (DVT), etc.

Predictors of outcomes of total knee replacement surgery

To identify pre-operative predictors of patient-reported outcomes of primary total knee replacement (TKR) surgery. The Elective Orthopaedic Centre database is a large prospective cohort of 1991 patients receiving primary TKR in south-west London from 2005 to 2008. The primary outcome is the 6-month post-operative Oxford Knee Score (OKS). To classify whether patients had a clinically important outcome, we calculated a patient acceptable symptom state (PASS) for the 6-month OKS related to satisfaction with surgery. Potential predictor variables were pre-operative OKS, age, sex, BMI, deprivation, surgical side, diagnosis, operation type, American Society of Anesthesiologists grade and EQ5D anxiety/depression. Regression modelling was used to identify predictors of outcome. The strongest determinants of outcome include pre-operative pain/function-those with less severe pre-operative disease obtain the best outcomes; diagnosis in relation to pain outcome-patients with RA did better than those with OA; deprivation-those living in poorer areas had worse outcomes; and anxiety/depression-worse pre-operative anxiety/depression led to worse pain. Differences were observed between predictors of pain and functional outcomes. Diagnosis of RA and anxiety/depression were associated with pain, whereas age and gender were specifically associated with function. BMI was not a clinically important predictor of outcome. This study identified clinically important predictors of attained pain/function post-TKR. Predictors of pain were not necessarily the same as functional outcomes, which may be important in the context of a patient's expectations of surgery. Other predictive factors need to be identified to improve our ability to recognize patients at risk of poor TKR outcomes.

Rationing of total knee replacement: a cost-effectiveness analysis on a large trial data set

ObjectivesMany UK primary care trusts have recently introduced eligibility criteria restricting total knee replacement (TKR) to patients with low pre-operative Oxford Knee Scores (OKS) to cut expenditure. We evaluate these...

Assessing patients for joint replacement: can pre-operative Oxford hip and knee scores be used to predict patient satisfaction following joint replacement surgery and to guide patient selection?

Assessing patients for joint replacement: can pre-operative Oxford hip and knee scores be used to predict patient satisfaction following joint replacement surgery and to guide patient selection?

Assessing patients for joint replacement

We obtained pre-operative and six-month post-operative Oxford hip (OHS) and knee scores (OKS) for 1523 patients who underwent total hip replacement and 1784 patients who underwent total knee replacement. They all also completed a six-month satisfaction question. Scatter plots showed no relationship between pre-operative Oxford scores and six-month satisfaction scores. Spearman’s rank correlation coefficients were -0.04 (95% confidence interval (CI) -0.09 to 0.01) between OHS and satisfaction and 0.04 (95% CI -0.01 to 0.08) between OKS and satisfaction. A receiver operating characteristic (ROC) curve analysis was used to identify a cut-off point for the pre-operative OHS/OKS that identifies whether or not a patient is satisfied with surgery. We obtained an area under the ROC curve of 0.51 (95% CI 0.45 to 0.56) for hip replacement and 0.56 (95% CI 0.51 to 0.60) for knee replacement, indicating that pre-operative Oxford scores have no predictive accuracy in distinguishing satisfied from dissatisfied patients. In the NHS widespread attempts are being made to use patient-reported outcome measures (PROMs) data for the purpose of prioritising patients for surgery. Oxford hip and knee scores have no predictive accuracy in relation to post-operative patient satisfaction. This evidence does not support their current use in prioritising access to care.

High tibial osteotomy in medial compartment osteoarthritis and varus deformity using the Taylor spatial frame: early results

We report the early results of high tibial osteotomy (HTO) in medial compartment osteoarthritis (OA) and varus deformity using the Taylor spatial frame (TSF). Between October 2005 and April 2007, 9 patients with medial compartment OA and varus deformity underwent TSF application and medial opening wedge HTO. Pre- and post-operative Oxford knee scores, SF-12 and visual analogue pain scores were recorded along with radiographic outcomes. Median follow-up was 19 months (range 15–35). Mean age at operation was 49 years (range 37–59). The median time spent in the frame was 18 weeks (range 12–37). The mean preoperative Oxford knee score was 28.7. This improved to a mean of 35.4 post-operatively (P = 0.0142). 6 (67%) patients had a documented pin-site infection. With TKR as an end point, the survival rate of HTOs was 88.9% at a median of 19 months follow-up. This study demonstrates that in selected patients the TSF provides a viable treatment option for performing HTO in medial compartment OA with varus deformity.

Preoperative lateral subluxation of the patella is a predictor of poor early outcome of Oxford phase-III medial unicompartmental knee arthroplasty

Background and purpose There is disagreement in the literature about the importance of patellofemoral joint degeneration and knee pain for the outcome of unicompartmental knee arthroplasty (UKA). We therefore investigated the importance of selected predictors including patellofemoral joint degeneration and the location of preoperative knee pain for the early outcome of UKA.Patients and methods The study group comprised 260 consecutive patients from 5 hospitals who underwent Oxford UKA for anteromedial osteoarthritis. Data were collected at baseline and included pain location, radiologically observed degeneration of the patellofemoral joint including subluxation of the patella, intraoperative cartilage status of the patellofemoral joint, disease-specific knee status, and Oxford knee score (OKS). Outcomes were evaluated after 1 year using the OKS, global patient satisfaction, and global patient result.Results The average OKS score at baseline was 24 (SD 7), and it was 40 (SD 8) at the 1-year follow-up. 94% of the patients claimed improvement after the operation and 90% were satisfied with the UKA. Lateral subluxation of the patella was a predictor of poor outcome, and the preoperative OKS score was also a predictor of outcome. Full-thickness cartilage loss at any location gave a similar outcome to that with a normal or near-normal joint surface, and likewise, preoperative anterior knee pain was not a predictor of outcome.Interpretation We conclude that the good early outcome after UKA in this study is in line with the best reported results. Patellofemoral degeneration should not be considered a contraindication to Oxford UKA. Patients with lateral subluxation of the patella have an increased risk of a poor result after UKA and should preferably be offered a total knee replacement.

Health-Related Quality of Life after Total Knee Replacement or Unicompartmental Knee Arthroplasty in an Urban Asian Population

Objective To examine health-related quality of life (HRQoL) after total knee replacement (TKR) or unicompartmental knee arthroplasty (UKA). Methods Asian adult patients undergoing either TKR or UKA in a hospital in Singapore between 2001 and 2006 were interviewed before surgery and 6 and 24 months postoperatively to obtain demographic information and HRQoL scores using the Short Form-36 Health Survey (SF-36) and the Oxford Knee Score (OKS). Results Data were collected from 2243, 1715, and 1113 patients at baseline and at 6 and 24 months, respectively. TKR patients had a lower preoperative OKS than UKA patients and lower preoperative scores on four subscales of the SF-36 ( P < 0.01). Both TKR and UKA patients' OKS and SF-36 subscale scores improved 6 months postoperatively except in the general health domain. SF-36 role physical and bodily pain scores showed the most improvement (40.9 and 33.0 points in TKR and 36.9 and 31.4 points in UKA patients, respectively). Two years after surgery, TKR patients' SF-36 scores and OKSs were not significantly different from those of UKA patients except for physical functioning scores. Multiple regression analysis adjusting for demographics showed that baseline scores were a significant predictor of the postoperative OKSs and scores on all SF-36 subscales ( P < 0.01), whereas the type of surgery was not associated with the postoperative scores. Conclusions Both TKR and UKA patients experienced significant improvements in HRQoL, particularly in the role physical and pain domains. After controlling for potential confounding variables, the type of surgery was not a significant predictor of patients' postoperative HRQoL scores.

The implications of damage to the lateral femoral condyle on medial unicompartmental knee replacement

With medial unicompartmental osteoarthritis (OA) there is occasionally a full-thickness ulcer of the cartilage on the medial side of the lateral femoral condyle. It is not clear whether this should be considered a contraindication to unicompartmental knee replacement (UKR). The aim of this study was to determine why these ulcers occur, and whether they compromise the outcome of UKR. Case studies of knees with medial OA suggest that cartilage lesions on the medial side of the lateral condyle are caused by impingement on the lateral tibial spine as a result of the varus deformity and tibial subluxation. Following UKR the varus and the subluxation are corrected, so that impingement is prevented and the damaged part of the lateral femoral condyle is not transmitting load. An illustrative case report is presented. Out of 769 knees with OA of the medial compartment treated with the Oxford UKR, 59 (7.7%) had partial-thickness cartilage loss and 20 (2.6%) had a full-thickness cartilage deficit on the medial side of the lateral condyle. The mean Oxford Knee Score (OKS) at the last follow-up at a mean of four years was 41.9 (13 to 48) in those with partial-thickness cartilage loss and 41.0 (20 to 48) in those with full-thickness loss. In those with normal or superficially damaged cartilage the mean was 39.5 (5 to 48) and 39.7 (8 to 48), respectively. There were no statistically significant differences between the pre-operative OKS, the final review OKS or of change in the score in the various groups. We conclude that in medial compartment OA, damage to the medial side of the lateral femoral condyle is caused by impingement on the tibial spine and should not be considered a contraindication to an Oxford UKR, even if there is extensive full-thickness ulceration of the cartilage.

Analysis of 13 early failures of the mobile bearing Oxford phase III unicompartmental knee prosthesis

The use of unicompartmental knee arthroplasty appears to be increasing despite a significant number of early revisions. This study looks at a consecutive series of such procedures. We retrospectively reviewed thirteen patients who had a revision of a unicompartmental knee replacement between January 2003 and March 2008 inclusively. During the study period, a total of 141 UKAs were performed in the reporting unit, of those 9 were revised to TKA. The indication for revision to TKA was determined from clinical records and radiographs. All patients who underwent revision were followed up using Oxford Knee Score. No preoperative Oxford Knee Scores were available. The study group consisted of six men and seven women. The preoperative diagnosis was osteoarthritis in all cases. The mean follow-up time was 16.4 ± 10.7 months (range: 2–36 months). The mean age of the patients at time of revision was 60.8 ± 9.7 years (range: 50–77 years). All patients had undergone medial UKA. The mean time interval between primary surgery and revision surgery was 21.5 ± 13.4 months (range: 5–48 months). The indications for revision included loosening of the tibial and/or femoral component (n = 7), progression of osteoarthritis to lateral compartment (n = 2), unexplained medial knee pain (n = 2) patellofemoral symptoms (n = 1), and insert dislocation (n = 1). The mean postoperative Oxford Knee Score at the latest follow-up evaluation was 14 ± 6.5 (range: 5–26). For the majority of patients, UKA provides reliable and reproducible results. However, UKA is a demanding procedure that needs special experience and includes a risk of early failure.

Influence of pre-operative variables on length of stay and outcome after unicompartmental knee replacement

The objective of this study was to determine whether pre-operative characteristics correlate with length of hospital stay or postoperative outcomes at 1 year following medial unicompartmental knee replacements (UKR). One hundred and eighty nine UKR patients and 223 knees were assessed pre-operatively and at one year post-operatively. The pre-operative variables of interest included: gender, age, body mass index (BMI), smoking history, uni- or bilateral procedures, pre-operative location, operative location, pre-operative Oxford Knee Score (OKS), clinical and functional American Knee Society Score (AKS) or Short Form-12 (SF-12). One year outcomes included the OKS, the clinical and functional AKS, SF-12, knee range of motion, and maximum and minimum visual analogue scale (VAS) pain scores, and length of hospital stay. Findings suggested that most pre-operative variables assessed correlated to maximum pain outcomes, and that the pre-operative clinical and functional AKS and SF-12 scores correlated with 1 year OKS and clinical AKS. Length of stay correlated with pre-operative OKS, SF-12, functional AKS, age and whether patients underwent uni- or bilateral procedures. Further study is recommended to compare these findings with alternative UKR populations.

The effect of preoperative symptom severity on functional outcome of total knee replacement—patients with the lowest preoperative scores achieve the lowest marks

To determine if the functional outcome of total knee replacement (TKR) was affected by the level of preoperative symptom severity, the association between preoperative Oxford Knee Scores (OKS), and 2 year OKS, American Knee Society clinical and function scores (AKSS) was assessed. Data were prospectively collected on 45 cases who had single joint osteoarthritis and no other comorbidities. We have specifically focused on patients with single knee involvement to remove the effect of multiple joint involvement and comorbidities on the OKS. The mean preoperative OKS was 21.4, postoperative OKS 40.0 and postoperative ROM 117 degrees. The postoperative mean AKSS was 86.7 and mean function score was 85.0. The ‘usual pain’ and ‘limp’ components of the OKS had the greatest rises and the ‘kneel’ component had the least improvement. Rather than all patients achieving uniform results post-TKR, patients with more severe symptoms achieved poorer absolute outcomes. The Spearman correlation coefficient between pre- and postoperative OKS was r = 0.4 ( p = 0.006). Although the results suggest that waiting too long before intervention compromises the final outcome, a correlation of 0.4 is not strong enough to necessitate change in current practice.

Unicompartmental knee arthroplasty: an intermediate report of survivorship after the introduction of a new system with analysis of failures

We describe the outcome of a series of 66 consecutive porous coated low contact stress (LCS) unicompartmental knee arthroplasty (UKA) cases performed in 52 patients for osteoarthritis (OA) by a single surgeon. Both survival, using the endpoint of revision for any cause, and knee function, using the Oxford knee score (OKS) as a validated outcome measure, were established in a retrospective review. At an average postoperative follow-up period of 5.9 years (range 5.1–6.6), there were 8 knees in patients who had died and 58 knees in those who were still living. We established the status of all knees, and prosthesis survival at 5 years was 89.7% (95% confidence interval, 81.6% to 97.7%). Technical errors were responsible for four of six failures and included progression of lateral compartment OA due to overcorrection, a medial tibial stress fracture due to poor pin placement, and a case where cement was required and poor cementing technique lead to early tibial component loosening. In the remaining 52 knees, the average preoperative OKS had improved significantly ( p<0.0001) from 37.0 (range, 17–49) to a postoperative score of 20.5 (range, 13–32). We conclude that the functional results following UKA compare favourably to total knee arthropasty (TKA); however, the survivorship of this series does not match that of published reports of TKA. The introduction of a new system of UKA includes the risk of early failures due to surgeon error, even when a surgeon is competent in UKA, warranting careful surveillance during this period.