Functional rating for knee arthroplasty: comparison of three scoring systems

[Functional outcomes and return to sports, work, and daily activities after revision UKA compared to primary UKA and TKA]

BACKGROUND

Unicompartmental knee arthroplasty (UKA), in addition to total knee arthroplasty (TKA), has been shown to be effective in the surgical treatment of knee osteoarthritis with appropriate patient selection. In clinical studies, it has demonstrated superior functional results with lower complication rates. In clinical practice, these advantages must be weighed against the disadvantage of an increased revision rate, especially in younger patients with sports and work activities.

OBJECTIVES

The aim of this study was to compare the functional outcome as well as the time to return to daily activities, work, and sports after revision of UKA to TKA with those of primary UKA and primary TKA using a matched-pair analysis.

MATERIALS AND METHODS

The study was based on a matched-pair analysis at two defined time points, always comparing 28 patients who underwent either revision of a UKA to a TKA, primary UKA, or primary TKA. Patients completed the Oxford Knee Score, UCLA score, Knee Society score, and WOMAC score during standardized follow-up. In addition, postoperative patient satisfaction and return to activities of daily living, work, and sports were recorded in a standardized manner, and a clinical examination was performed.

RESULTS

The four functional scores studied showed a common trend in favor of UKA, followed by primary TKA and revision TKA. The differences between converted UKA and primary TKA were not significant. However, at 3.2 years after the last surgery, the results of the converted UKA were significantly lower than those of the primary UKA. Return to work and sports tended to occur the earliest after UKA, followed by TKA and the revision group. All groups showed a tendency to engage in low-impact sports.

CONCLUSION

The functional results of revised UKA were significantly inferior to those of primary UKA based on a 3-year follow-up. Return to work, sports, and activities of daily living tended to take longer after revision than after primary implantation of either a UKA or a TKA.

Effects of Surgeon Handedness on the Outcomes of Unicompartmental Knee Arthroplasty: A Single Center's Experience

OBJECTIVE

Surgeon handedness has been widely discussed in operative surgery, and could cause clinical discrepancy. However, few studies have reported the effect of handedness on unicompartmental knee arthroplasty (UKA). Based on our clinical observation and case analysis, we aimed to find out the effects of surgeon handedness on UKA.

METHODS

We retrospectively studied 94 UKA procedures performed by one right-handed surgeon from January 2017 to December 2018 at a single medical center. The cases were divided into two groups by operation side (49 L-UKAs and 45 R-UKAs). Preoperative demographic data were collected. Imaging parameters (femorotibial and hip-knee-ankle angles and tibial-plateau retroversion) and joint function scores (Knee Society Score [KSS] and Oxford Knee Score [OKS]) were recorded. Patients were followed up regularly and Forgotten Joint Score (FJS) was calculated at the last follow-up. All data were compared between the two groups with independent-samples t-test, and paired t-test was used for intragroup comparisons.

RESULTS

The average follow-up was 26.7 ± 3.2 months. The average patient age was 63.5 ± 9.0 years and the average body mass index was 26.89 ± 3.43 kg/m² . There was no significant group difference in any preoperative characteristic. Both the KSS and OKS improved significantly after surgery (p < 0.05). No significant group difference was found between the KSS or OKS at any follow-up visit. The varus or valgus of tibial component was 3.57 ± 1.42° on the left side and 3.19 ± 1.56° on the right side (p = 0.45). The varus or valgus of femoral component was 7.81 ± 2.43° in patients undergoing L-UKA and 7.05 ± 2.90° in those undergoing R-UKA (p = 0.04). No statistical differences were found in outliers of component orientation on both sides. The femorotibial and hip-knee-ankle angles improved significantly in both groups, and there was no significant group difference in either lower limb alignment or tibial-plateau retroversion. The complication rate was 8.16% (4/49) in the L-UKA group and 6.67% (3/45) in the R-UKA group. There was no correlation between prosthesis orientation and early joint function score.

CONCLUSIONS

Surgeon handedness may cause a worse prosthetic orientation on femoral side during surgeon's non-dominant UKA, and surgeons should be cautious of bone resection and prosthesis implantation. However, radiographic difference did not bring variations on short-term clinical outcomes or lower limb alignment.

Assessing knee functionality: systematic review of validated outcome measures

BACKGROUND

Functional rating scales allow clinicians to document and quantify alterations and progression of recovery processes. There is neither awareness of numerous knee scales nor are they easy to find or compare to select the most suitable.

OBJECTIVES

We aimed to compile validated knee functional rating tools and analyse the methodological quality of their validation studies. Also, we aimed to provide an operational document of the outcome measures addressing descriptions of parameters, implementations, instructions, interpretations and languages, to identify the most appropriate for future interventions.

METHODS

A systematic review involved a search of PubMed, Web of Science, CINAHL, Scopus, and Dialnet databases from inception through September 2020. The main inclusion criteria were available functional rating scales/questionnaires/indexes for knees and validation studies. Methodological quality was analyzed with the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) and COnsensus-based Standards for the selection of health Measurement Instruments Risk of Bias (COSMIN-RB).

RESULTS

We selected 73 studies. The studies investigated 41 knee rating tools (general, 46%, and specific, 54%) and 71 validations, including 29,742 individuals with knee disorders. QUADAS-2 obtained the best results in patient selection and index test (applicability section). COSMIN-RB showed the highest quality in construct validity (most analyzed metric property). The specific tools were mainly designed for prosthesis and patellofemoral and anterior cruciate ligament injuries. More considered issues were specific function (93%), especially gait, pain/sensitivity (81%), and physical activity/sports (56%).

CONCLUSIONS AND IMPLICATIONS

We conducted a necessary, useful, unlimited-by-time and feasible compilation of validated tools for assessing knee functional recovery. The methodological quality of the validations was limited. The best validations were for the Copenhagen Knee Range of Motion Scale in osteoarthritis and arthroplasties, Knee Outcome Survey Activities of Daily Living and Lysholm Knee Score for general knee disorders and the Tegner Activity Score for anterior cruciate ligament injuries. The operational document for the scales provides necessary data to identify the most appropriate.

Cross-cultural translation and validation of the Chinese Oxford Knee Score and the Activity and Participation Questionnaire

OBJECTIVE

To cross-culturally translate and validate the Chinese versions of the Oxford Knee Score (OKS) and the Activity and Participation Questionnaire (APQ) in patients with end-stage knee osteoarthritis who are also candidates for knee replacement.

METHODS

The Chinese version of the OKS and APQ was completed by standard forward-backward translation and adaption. The feasibility was validated by a pretest in 30 patients. The final version together with the Short Form-36 (SF-36), EQ-5D, and EQ visual analog scale were assessed in 150 patients, and the OKS and APQ were repeated in 30 patients after a 2-week interval. The psychometric properties of the OKS and APQ were evaluated for test-retest reliability using intraclass correlation coefficients (ICCs), internal consistency using Cronbach's α, and construct validity using Spearman's correlation analysis.

RESULTS

All patients were able to understand and complete both the OKS and APQ without difficulty (i.e. no missing data). The ICCs were 0.959 for the OKS, 0.956 for the APQ for total scores, and >0.7 for each item. Cronbach's α was greater than 0.7, and the corrected item-total correlation was greater than 0.4 for each item of both questionnaires. The OKS and APQ showed better correlations with questions from the pain and function domains than with those from the mental status domains of the SF-36 and EQ-5D. No floor or ceiling effect was identified in either questionnaire.

CONCLUSIONS

The Chinese versions of the OKS and APQ are easy to understand and complete and showed good reliability and validity. They can be used to assess patient-reported outcomes after undergoing knee replacement in mainland China.

Which Patients Require a Contralateral Total Knee Arthroplasty Within 5 Years of Index Surgery?

Osteoarthritis (OA) of the knee often presents bilaterally. However, not all patients with severe bilateral knee OA require bilateral total knee arthroplasty (TKA). This study aims to identify predictive factors for contralateral TKA in patients presenting with severe bilateral knee OA undergoing unilateral TKA. We prospectively collected perioperative data from 209 consecutive patients of a single surgeon who had severe bilateral OA knees at presentation. All patients underwent unilateral TKA on the more symptomatic knee. Patients were then stratified by their need for a contralateral TKA within the next 5 years. Using regression analysis, we compared patients who underwent contralateral knee surgery within 5 years (n = 115) against patients who did not (n = 94), so as to create a predictive model. Significant factors identified by the multiple regression models were incorporated into a decision tree using classification and regression tree analysis. Body mass index (BMI), degree of varus angulation, and Oxford knee scores were identified as significant predictive factors. The generated decision tree model was able to stratify patients according to their BMI and Oxford scores into four subgroups, the highest with more than 90% odds of contralateral surgery and the lowest with less than 40% odds of contralateral surgery. BMI, degree of varus angulation, and preoperative Oxford knee scores seem to predict the need for contralateral TKA in patients with severe bilateral OA knees undergoing unilateral TKA. These patients should be counseled on their requirement for the second TKA based on these factors.

Successful adaption of the Banff Patella Instability Instrument (BPII) 2.0 into German

PURPOSE

The aim of this study was to adapt, translate, and validate the Banff Patella Instability Instrument (BPII) 2.0 into German, enabling its use by German-speaking professionals for the evaluation of patients who present with patellofemoral instability.

METHODS

Forward and backward translation was performed according to international recommendations. The final German version of the BPII 2.0 was investigated in patients with confirmed diagnoses of recurrent patellofemoral instability in Germany, Austria, and Switzerland. All patients received two packages of questionnaires, each containing the BPII 2.0, Kujala scoring questionnaire, Norwich Patella Instability scoring questionnaire, Short Form-36 (SF-36), and a visual analogue scale (VAS)-scale for pain and disability. The first and second packages of questionnaires were to be completed 7 days apart. The following parameters were assessed: internal consistency, test-retest reliability, floor and ceiling effects, and construct validity.

RESULTS

The study population consisted of 64 patients (24 males and 40 females). The average age of the patients was 22 ± 6 years. The internal consistency (Cronbach's alpha) was excellent at both time points (0.93 and 0.95), and the test-retest reliability (ICC) was good (0.89). There were no floor or ceiling effects. There were statistically significant correlations between the BPII 2.0 and all other outcome measures apart from SF-36 mental health.

CONCLUSION

The BPII 2.0 was successfully adapted into German. It is a reliable and valid instrument for evaluation of German-speaking patients who present with patellofemoral instability.

LEVEL OF EVIDENCE

III.

A Systematic Review of Measurement Properties of Patient-Reported Outcome Measures Used in Patients Undergoing Total Knee Arthroplasty

BACKGROUND

While clinical research on total knee arthroplasty (TKA) outcomes is prevalent in the literature, studies often have poor methodological and reporting quality. A high-quality patient-reported outcome instrument is reliable, valid, and responsive. Many studies evaluate these properties, but none have done so with a systematic and accepted method. The objectives of this study were to identify patient-reported outcome measures (PROMs) for TKA, and to critically appraise, compare, and summarize their psychometric properties using accepted methods.

METHODS

MEDLINE, EMBASE, SCOPUS, Web of Science, PsycINFO, and SPORTDiscus were systematically searched for articles with the following inclusion criteria: publication before December 2014, English language, non-generic PRO, and evaluation in the TKA population. Methodological quality and evidence of psychometric properties were assessed with the COnsensus-based standards for the selection of health Status Measurement INstruments (COSMIN) checklist and criteria for psychometric evidence proposed by the COSMIN group and Terwee et al.

RESULTS

One-hundred fifteen studies on 32 PROMs were included in this review. Only the Work, Osteoarthritis or joint-Replacement Questionnaire, the Oxford Knee Score, and the Western Ontario and McMaster Universities Arthritis Index had 4 or more properties with positive evidence.

CONCLUSION

Most TKA PROMs have limited evidence for their psychometric properties. Although not all the properties were studied, the Work, Osteoarthritis or joint-Replacement Questionnaire, with the highest overall ratings, could be a useful PROM for evaluating patients undergoing TKA. The methods and reporting of this literature can improve by following accepted guidelines.

No Differences Identified in Transverse Plane Biomechanics Between Medial Pivot and Rotating Platform Total Knee Implant Designs

BACKGROUND

Total knee arthroplasties (TKAs) using well-designed, fixed bearing prostheses, such as medial pivot (MP), have produced good long-term results. Rotating-platform, posterior-stabilized (RP-PS) mobile bearing implants were designed to decrease polyethylene wear. Sagittal and coronal plane TKA biomechanics are well examined and correlated to polyethylene wear. However, limited research findings describe this relationship in transverse plane. We assumed that although axial plane biomechanics might not be the most destructive parameters on polyethylene wear, it is important to clarify their role because both joint kinematics and kinetics in all 3 planes are important input parameters for TKA wear testing (International Organization for Standardization 14243-1 and 14343-3). Our hypothesis was that transverse plane overall range of motion (ROM) and/or peak moment show differences that reflect on wear advantages when compared RP-PS implants to MP designs.

METHODS

Two groups (MPs = 24 and RP-PSs = 22 subjects) were examined by using 3D gait analysis. The variables were total internal-external rotation (IER) ROM and peak IER moments.

RESULTS

No statistically significant difference was demonstrated between the 2 groups in kinetics (P = .389) or kinematics (P = .275).

CONCLUSION

In the present study, no wear advantages were found between 2 TKAs. Both designs showed identical kinetics at the transverse plane in level-ground walking. Kinematic analysis could not illustrate any statistically significant difference in terms of overall IER ROM. Nevertheless, kinematic gait pattern differences observed possibly reflect different patterns of joint surface motion or abnormal gait patterns. Thus, wear testing with various input waveforms combined with functional data analysis will be necessary to identify the actual effects of gait variability on polyethylene wear.

Patient-reported outcome measures after total knee arthroplasty: a systematic review

Objectives

A lack of connection between surgeons and patients in evaluating the outcome of total knee arthroplasty (TKA) has led to the search for the ideal patient-reported outcome measure (PROM) to evaluate these procedures. We hypothesised that the desired psychometric properties of the ideal outcome tool have not been uniformly addressed in studies describing TKA PROMS.

Methods

A systematic review was conducted investigating one or more facets of patient-reported scores for measuring primary TKA outcome. Studies were analysed by study design, subject demographics, surgical technique, and follow-up adequacy, with the ‘gold standard’ of psychometric properties being systematic development, validity, reliability, and responsiveness.

Results

A total of 38 articles reported outcomes from 47 different PROMS to 85 541 subjects at 26.3 months (standard deviation 30.8) post-operatively. Of the 38, eight developed new scores, 20 evaluated existing scores, and ten were cross-cultural adaptation of existing scores. Only six of 38 surveyed studies acknowledged all ‘gold standard’ psychometric properties. The most commonly studied PROMS were the Oxford Knee Score, New Knee Society Score, Osteoarthritis Outcome Score, and Western Ontario and McMaster Universities Osteoarthritis Index.

Conclusions

A single, validated, reliable, and responsive PROM addressing TKA patients’ priorities has not yet been identified. Moreover, a clear definition of a successful procedure remains elusive.

Cite this article: Bone Joint Res 2015;4:120–127

Validation of a prediction model that allows direct comparison of the Oxford Knee Score and American Knee Society clinical rating system

This study demonstrates a significant correlation between the American Knee Society (AKS) Clinical Rating System and the Oxford Knee Score (OKS) and provides a validated prediction tool to estimate score conversion.

A total of 1022 patients were prospectively clinically assessed five years after TKR and completed AKS assessments and an OKS questionnaire. Multivariate regression analysis demonstrated significant correlations between OKS and the AKS knee and function scores but a stronger correlation (r = 0.68, p < 0.001) when using the sum of the AKS knee and function scores. Addition of body mass index and age (other statistically significant predictors of OKS) to the algorithm did not significantly increase the predictive value.

The simple regression model was used to predict the OKS in a group of 236 patients who were clinically assessed nine to ten years after TKR using the AKS system. The predicted OKS was compared with actual OKS in the second group. Intra-class correlation demonstrated excellent reliability (r = 0.81, 95% confidence intervals 0.75 to 0.85) for the combined knee and function score when used to predict OKS.

Our findings will facilitate comparison of outcome data from studies and registries using either the OKS or the AKS scores and may also be of value for those undertaking meta-analyses and systematic reviews.

Cite this article: Bone Joint J 2015;97-B:503–9.

Clinimetric quality of the new 2011 Knee Society score: high validity, low completion rate

BACKGROUND

The demands of the younger and more active current total knee arthroplasty (TKA) patients are not in line with the current outcome assessments. Therefore, new questionnaires are developed or adjusted, as with the popular 1989 Knee Society Score (KSS). This study is the first to investigate the clinimetric parameters of the patient-reported outcome measurement (PROM) part of the 2011 KSS.

METHODS

Four-hundred-fifteen primary Dutch TKA patients were scored using the PROM part of the 2011 KSS. The scale is subdivided into an Objective (not evaluated), Satisfaction, Expectation and Function subscales. Clinimetric quality was evaluated by response and completion rate, test-retest reliability (n=29, intraclass correlation coefficient), internal consistency (n=172, Cronbach's alpha), construct validity (Pearson's correlations with 1989 KSS (n=75) and KOOS-PS (n=139)) and responsiveness (n=20, paired-samples t-test, effect sizes and floor and ceiling effects).

RESULTS

A response rate of 96% and completion rate of 43% were found. Reliability and internal consistency proved excellent with ICCs≥0.79 and Cronbach's alpha≥0.76 for all subscales. Strong correlations were found between the Function subscales of the 2011 KSS and KOOS-PS (r=-0.60 to -0.83). All subscales improved significantly after intervention, with exception of Walking & Standing and Discretionary Activities. 23% reached the maximum score postoperatively in Walking & Standing, indicating a ceiling effect.

CONCLUSIONS

The 2011 KSS is a reliable, internal consistent, construct valid and responsive questionnaire to assess the outcome of the Dutch TKA patients. Optimizations (e.g. shortening the scale, simplified design) are recommended to increase the disappointing completion rate.

CLINICAL RELEVANCE

The 2011 KSS is a reliable, internal consistent, construct valid and responsive questionnaire to assess the outcome of the Dutch TKA patients.

Better functional and similar pain outcomes in osteoarthritis compared to rheumatoid arthritis after primary total knee arthroplasty: a cohort study

OBJECTIVE

To determine the association of the underlying diagnosis with limitation in activities of daily living (ADL) and pain in patients undergoing primary total knee arthroplasty (TKA).

METHODS

Prospectively collected data from the Mayo Clinic Total Joint Registry were used to assess the association of diagnosis with moderate-severe limitation in ADL and moderate-severe pain at 2 and 5 years after primary TKA, using multivariable-adjusted logistic regression analyses. We calculated odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

There were 7,139 primary TKAs at 2 years and 4,234 at 5 years. In multivariable-adjusted analyses, compared with rheumatoid arthritis (RA)/inflammatory arthritis, osteoarthritis (OA) was associated with significantly lower moderate-severe ADL limitation at 2 years (OR 0.5 [95% CI 0.3-0.8]) (P = 0.004) and at 5 years (OR 0.5 [95% CI 0.3-0.9]) (P = 0.02). There was no significant association of diagnosis of OA with moderate-severe pain at 2 years (OR 1.2 [95% CI 0.5-2.7]) (P = 0.68) or at 5 years (OR 1.0 [95% CI 0.3-3.7]) (P = 1.0).

CONCLUSION

We found that patients with OA who underwent primary TKA had better ADL outcomes compared to patients with RA/inflammatory arthritis at 2 and 5 years. On the other hand, the pain outcomes after primary TKA did not differ in OA versus RA. This suggests a discordant effect of underlying diagnosis on pain and function outcomes after TKA. These novel findings can be used to better inform both patients and surgeons about expected pain and function outcomes after primary TKA.

Total knee replacement in the obese patient: comparing computer assisted and conventional technique

PURPOSE

Obesity is being considered a "global epidemic." Surgical procedures are rendered more difficult in obese patients. We aimed to see whether any benefits were evident with use of computer navigation during total knee replacement in these cases.

METHODS

A retrospective analysis of 287 TKR performed by a single surgeon was undertaken, including 133 TKR undertaken with computer navigation and 154 using standard instrumentation. Each group was further divided into subgroups depending on whether the patients were obese or nonobese.

RESULTS

We found that TKR in obese patients took longer with standard instruments, but not with computer navigation. A chronological analysis revealed that the surgeon progressively got quicker using computer navigation to the point that there was no difference in time with either of the operative techniques in obese patients. The mid-term clinical outcomes at five years were similar. Computer navigated TKR were more consistently accurately aligned.

CONCLUSIONS

In obese patients, a dual advantage is provided by computer navigation: better alignment and no time penalty.

Mobile vs fixed-bearing total knee arthroplasty performed by a single surgeon: a 4- to 6.5-year randomized, prospective, controlled, double-blinded study

The superiority between posterior-stabilized mobile-bearing and fixed-bearing designs still remains controversial. Fifty-six consecutive patients undergoing primary, unilateral knee arthroplasty for osteoarthritis were randomly assigned to receive either a mobile-bearing (29 patients) or fixed-bearing (27 patients) prosthesis. We report the results at 4 to 6.5 years (mean, 5.5) follow-up. The Knee Society knee scores, pain scores, functional scores and Oxford knee scores were not statistically different (P > 0.05) between the two groups. Mean postoperative range-of-motion of mobile-bearing knees was significantly greater than that of fixed-bearing knees (127º versus 111º, P = 0.011). 72% of patients could sit cross legged, 48% could sit on the floor, and 17% could squat. Kaplan-Meier survival rate was 100%. No spin-out of mobile bearing was observed. The radiological analysis showed no osteolysis or implant loosening.

Five-year results of a randomised controlled trial comparing mobile and fixed bearings in total knee replacement

There is conflicting evidence about the merits of mobile bearings in total knee replacement, partly because most randomised controlled trials (RCTs) have not been adequately powered. We report the results of a multicentre RCT of mobile versus fixed bearings. This was part of the knee arthroplasty trial (KAT), where 539 patients were randomly allocated to mobile or fixed bearings and analysed on an intention-to-treat basis. The primary outcome measure was the Oxford Knee Score (OKS) plus secondary measures including Short Form-12, EuroQol EQ-5D, costs, cost-effectiveness and need for further surgery. There was no significant difference between the groups pre-operatively: mean OKS was 17.18 (sd 7.60) in the mobile-bearing group and 16.49 (sd 7.40) in the fixed-bearing group. At five years mean OKS was 33.19 (sd 16.68) and 33.65 (sd 9.68), respectively. There was no significant difference between trial groups in OKS at five years (-1.12 (95% confidence interval -2.77 to 0.52) or any of the other outcome measures. Furthermore, there was no significant difference in the proportion of patients with knee-related re-operations or in total costs. In this appropriately powered RCT, over the first five years after total knee replacement functional outcomes, re-operation rates and healthcare costs appear to be the same irrespective of whether a mobile or fixed bearing is used.

Income and patient-reported outcomes (PROs) after primary total knee arthroplasty

BACKGROUND

To assess whether income is associated with patient-reported outcomes (PROs) after primary total knee arthroplasty (TKA).

METHODS

We used prospectively collected data from the Mayo Clinic Total Joint Registry to assess the association of income with index knee functional improvement, moderate to severe pain and moderate to severe activity limitation at 2-year and 5-year follow-up after primary TKA using multivariable-adjusted logistic regression analyses.

RESULTS

There were 7, 139 primary TKAs at 2 years and 4, 234 at 5 years. In multivariable-adjusted analyses, at 2-year follow-up, compared to income > US$45, 000, lower incomes of ≤ US$35, 000 and > US$35, 000 to 45, 000 were associated (1) significantly with moderate to severe pain with an odds ratio (OR) 0.61 (95% CI 0.40 to 0.94) (P = 0.02) and 0.68 (95% CI 0.49 to 0.94) (P = 0.02); and (2) trended towards significance for moderate to severe activity limitation with OR 0.78 (95% CI 0.60 to 1.02) (P = 0.07) and no significant association with OR 0.96 (95% CI 0.78 to 1.20) (P = 0.75), respectively. At 5 years, odds were not statistically significantly different by income, although numerically they favored lower income. In multivariable-adjusted analyses, overall improvement in knee function was rated as 'better' slightly more often at 2 years by patients with income in the ≤ US$35, 000 range compared to patients with income > US$45, 000, with an OR 1.9 (95% CI 1.0 to 3.6) (P = 0.06).

CONCLUSIONS

We found that patients with lower income had better pain outcomes compared to patients with higher income. There was more improvement in knee function, and a trend towards less overall activity limitation after primary TKA in lower income patients compared to those with higher incomes. Insights into mediators of these relationships need to be investigated to understand how income influences outcomes after TKA.

The association between radiographic severity and pre-operative function in patients undergoing primary knee replacement for osteoarthritis

OBJECTIVE

To determine the association between radiographic osteoarthritis (OA) and pre-operative function in patients undergoing primary knee replacement.

METHODS

Single centre study examining pre-operative outcomes in a consecutive series of 525 patients who underwent primary knee replacement for OA between January 2006 and December 2007. Pre-operative data included: demographics, American Society of Anaesthesiologists (ASA) status and OA in the contralateral knee. The International Knee Society (IKS) rating and Short Form-12 (SF-12) were recorded for each patient. Pre-operative radiographs were read by a single observer for Kellgren and Lawrence (K&L) grading and Osteoarthritis Research Society International (OARSI) atlas features. Multiple linear regression was used to assess the strength of associations between radiographic OA severity and function, adjusting for clinically relevant variables.

RESULTS

Lateral tibiofemoral osteophyte grade was an independent predictor of pre-operative function as determined by the functional sub-scale of the IKS in patients undergoing primary knee replacement (coefficient=2.58, p=0.033). No associations were evident between pre-operative function and modified K&L, joint space narrowing, Ahlbäck attrition and coronal plane deformity. Other statistically significant predictors of poorer pre-operative function included: advancing age, female gender, knee pain and poorer SF-12 mental component summary scores which including osteophyte grade accounted for 24.6% of the variation in functional scores, (r=0.496).

CONCLUSION

Osteophytes in the lateral compartment of the knee were associated with pre-operative function in patients with advanced knee OA. Further studies are required which examine individual radiographic features specifically in patients with advanced knee OA to determine their relationship to pre-operative pain and function.

[Clinical and functional outcome of unicompartmental knee arthroplasty: influence of the mechanical axis correction]

OBJECTIVES

Clinical and functional outcome of the knee after Unicompartmental Knee Arthroplasty (UKA) and its correlation with lower limb mechanical axis correction.

MATERIAL AND METHODS

We have reviewed the outcome of 29 UKA, corresponding to 29 patients, with an average follow-up of 4.5 years (3-6 years). The distribution was, 21 women and 8 men, 11 unicompartmental osteoarthritis, 17 femoral condyle necrosis and 1 tibial plateau necrosis, and 27 medial versus 2 lateral affected compartments. The clinical-functional situation of the knees was assessed through the Knee Society Score (KSS), and the mechanical axis through long standing film. To calculate the statistical non-parametric correlation between the different parameters, Spearman's coefficient was used.

RESULTS

In the last review, the increases in the mean clinical KSS and functional KSS were significantly different, with +31.24 (±15.7) and +43.66 (±18.4) points, respectively. The mean change in the femorotibial angle was 2°±4°. We did not find any correlation with statistical significance between the average increases obtained in KS scores and: the alignment of the knee before and after the surgery; the thickness of the inserted polyethylene; the variation of the posterior tibial inclination; Insall-Salvati's index. There was no statistically significant association between the variation in the total KS score and the type of implant or the surgical technique used.

CONCLUSION

We did not find any correlation between the clinical results and the radiological measurements in this population.

Does circumpatellar electrocautery improve the outcome after total knee replacement?: a prospective, randomised, blinded controlled trial

The incidence of anterior knee pain following total knee replacement (TKR) is reported to be as high as 49%. The source of the pain is poorly understood but the soft tissues around the patella have been implicated. In theory circumferential electrocautery denervates the patella thereby reducing efferent pain signals. However, there is mixed evidence that this practice translates into improved outcomes. We aimed to investigate the clinical effect of intra-operative circumpatellar electrocautery in patients undergoing TKR using the LCS mobile bearing or Kinemax fixed bearing TKR. A total of 200 patients were randomised to receive either circumpatellar electrocautery (diathermy) or not (control). Patients were assessed by visual analogue scale (VAS) for anterior knee pain and Oxford knee score (OKS) pre-operatively and three months, six months and one year post-operatively. Patients and assessors were blinded. There were 91 patients in the diathermy group and 94 in the control. The mean VAS improvement at one year was 3.9 in both groups (control; -10 to 6, diathermy; -9 to 8, p < 0.001 in both cases, paired, two-tailed t-test). There was no significant difference in VAS between the groups at any other time. The mean OKS improvement was 17.7 points (0 to 34) in the intervention group and 16.6 (0 to 42) points in the control (p = 0.36). There was no significant difference between the two groups in OKS at any other time. We found no relevant effect of patellar electrocautery on either VAS anterior knee pain or OKS for patients undergoing LCS and Kinemax TKR.

Revision of medial Oxford unicompartmental knee replacement to a total knee replacement: similar to a primary?

Unicompartmental knee replacement (UKR) is an option for the treatment of isolated medial compartment osteoarthritis. A commonly perceived potential advantage is that revision of a UKR is straightforward. The purpose of this study was to determine the early outcomes and the level of complexity of revisions of Oxford UKRs performed at our hospital. A retrospective review of a prospective database of all phase III Oxford UKRs was undertaken. This identified 89 Oxford UKRs which were revised at our institution between 2002 and 2008. The median time from the primary procedure to revision was 19 months (interquartile range 2-73 months). Nine were revised to another UKR. Eighty were revised to a total knee replacement (TKR). Fifty-three were revised with primary TKR components. Twenty-seven were revised using stems and/or augments. The median overall tibial component thickness (including augments) was 15 mm. Forty-five knees had an overall tibial component thickness greater than 15 mm. A primary Oxford UKR bearing thickness of greater than 6mm was associated with an increased likelihood of requiring revision components. On the basis of this review, tibial bone defects were commonly encountered when revising UKRs. Reconstruction with either an augment and a stem, or thick polyethylene component was often required. We recommend that the potential complexity of revision for UKR failure should be borne in mind when considering a primary Oxford UKR.

Effect of psychopathology on patient-perceived outcomes of total knee arthroplasty within an indigent population

BACKGROUND

Factors other than surgical technique and implants impact patient outcomes following a total knee arthroplasty. The purpose of this study was to analyze the effects of psychopathology on the rate of improvement following total knee arthroplasty in an indigent population.

METHODS

One hundred and fifty-four consecutive indigent patients undergoing a primary total knee arthroplasty for arthritis were enrolled and available for follow-up. Patients were classified as having psychopathology on the basis of the presence of somatization, depression, and/or a panic or anxiety disorder as assessed with the Patient Health Questionnaire. Outcome measures were completed preoperatively and one year postoperatively. Univariate analyses, controlled for sex and age, were used to compare the rates of improvement in patients who exhibited psychopathology with the rates in those without psychopathology.

RESULTS

Fifty-four patients (35%) were diagnosed with at least one Axis-I psychological disorder. The psychopathology group showed significantly lower Short Form-36 mental component summary scores both at baseline and one year postoperatively (p < 0.001 for both). The psychopathology group also reported significantly higher levels of perceived disability at baseline on the Pain Disability Questionnaire (p < 0.001) and worse scores on the Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.004); however, the improvement on both of these scales did not differ significantly between the two groups (p > 0.05). The Knee Society Score differed significantly between the two groups at both baseline and the one-year follow-up evaluation (p = 0.003 and p = 0.001, respectively), but there was no significant difference in the total rate of improvement between the two comparison groups (p > 0.05).

CONCLUSIONS

Not only is there a high prevalence of psychopathology in the indigent population, but psychopathology may result in lower patient-perceived outcome scores at one year after a total knee arthroplasty. Even though outcome scores may be worse for patients with psychopathology, our study showed that these patients still benefit, with the same degree of improvement in function.

Comparison of patient-reported and clinician-assessed outcomes following total knee arthroplasty

BACKGROUND

Although the necessity of long-term follow-up after total knee arthroplasty is unquestioned, this task may become burdensome as greater numbers of total knee arthroplasties are performed. We sought to use comparisons with clinician-assessed values to determine whether patients could reliably assess their own outcome with use of a combination of American Knee Society Score and Oxford Knee Score questionnaires and self-reported knee motion. We hypothesized that patients would self-report worse pain and function and a similar range of knee motion than clinicians would.

METHODS

One hundred and forty patients (181 knees) scheduled for routine follow-up at two centers after primary total knee arthroplasty were mailed American Knee Society Score and Oxford Knee Score questionnaires, a set of photographs illustrating knee motion in 5° increments for comparison with the patient's range of knee motion, and a goniometer with instructions. The patient's American Knee Society Score, Oxford Knee Score, and knee motion were then independently assessed within two weeks of the self-evaluation by one of three clinicians who had not been involved with the surgery. Patient-reported and clinician-assessed measures were compared with use of a paired-sample t test and the Spearman correlation coefficient.

RESULTS

The mean patient-reported American Knee Society pain subscore was 4 points worse than the clinician-assessed score, and the function subscore was 10 points worse (p < 0.001 for both). The mean Oxford Knee Score did not differ significantly between the patient self-assessment and the clinician assessment (p = 0.05). The mean maximum flexion reported by the patient with use of the photographs differed by <1° from the mean value reported by the patient with use of the goniometer or the mean value measured by the clinician; these differences were not clinically important.

CONCLUSIONS

Patients' self-reported American Knee Society pain and function subscores were worse than the corresponding clinician assessments, but the two Oxford Knee Scores were similar. Range of knee motion may reasonably be self-assessed by comparison with photographs. Long-term follow-up of patients after total knee arthroplasty may be possible with use of patient-reported measures, alleviating the burden of clinic visits yet maintaining contact, but further studies involving other validated instruments is warranted.

Patellar resurfacing in total knee replacement: five-year clinical and economic results of a large randomized controlled trial

BACKGROUND

There is conflicting evidence regarding the merits of patellar resurfacing during total knee arthroplasty, as many of the previous randomized controlled trials have not been adequately powered.

METHODS

A pragmatic, multicenter, randomized controlled trial was initiated in 1999 in the United Kingdom. Within a partial factorial design, 1715 patients were randomly allocated to receive or not receive patellar resurfacing during total knee arthroplasty. The primary outcome measure was the Oxford Knee Score; secondary measures included the Short Form-12, the EuroQoL 5D, cost, cost-effectiveness, and the need for subsequent knee surgery.

RESULTS

The mean Oxford Knee Score was 35 points at five years postoperatively in both groups. There was no significant difference between the groups with respect to the mean Oxford Knee Score (difference, 0.59 point; 95% confidence interval, -0.58 to 1.76 points) or any other outcome measure at five years postoperatively. The outcome was not affected by whether the patella was domed or anatomic. There was no significant difference between the two groups with respect to the prevalence of knee-related readmission, of minor or intermediate reoperation, or of subsequent patella-related surgery. The total health care cost for the primary arthroplasty, subsequent monitoring, and any revision surgery did not differ significantly between the two groups.

CONCLUSIONS

In the largest randomized controlled trial of patellar resurfacing reported to date, the functional outcome, reoperation rate, and total health care cost five years after primary total knee arthroplasty were not significantly affected by the addition of patellar resurfacing to the surgical procedure.

Does electric stimulation of the vastus medialis muscle influence rehabilitation after total knee replacement?

Patients with knee osteoarthritis present with reduced quadriceps muscle strength, which is partially responsible for impaired function and disability. Although total knee replacement (TKR) is an effective surgical procedure, residual muscle weakness is not usually addressed and may persist for years postoperatively. This article reports the results of a prospective, randomized, controlled trial evaluating the effect of electric muscle stimulation of the vastus medialis on the speed and effort of walking, quality of life, and knee performance in patients undergoing TKR. Seventy patients who underwent TKR were randomly divided into 2 groups. Patients in group A received electric muscle stimulation and standard physiotherapy for 6 weeks, while patients in group B received physiotherapy only. All patients were assessed with both subjective and objective clinical scales preoperatively and at 6, 12, and 52 weeks postoperatively. Patients in group A demonstrated a statistically significant increase in walking speed, Oxford Knee Score, and American Knee Society function score compared to those in group B at 6 weeks (P=.003, .001, and .001, respectively) and at 12 weeks (all P=.001). A statistically significant increase in the SF-36 physical component summary score was observed at 6, 12, and 52 weeks (all P=.001). Three patients found the sensation of the electrical stimulation uncomfortable and abandoned its use. No skin reactions and surgical site infections were observed. Electrical stimulation of the vastus medialis muscle in addition to conventional physiotherapy improves functional recovery and early rehabilitation after TKR.

Limitations of the Knee Society Score in evaluating outcomes following revision total knee arthroplasty

BACKGROUND

Traditionally, the results of revision total knee arthroplasty have been determined with use of surgeon-based measures such as the Knee Society rating system. Recently, outcome and quality-of-life measures have shifted toward a greater emphasis on patient-based evaluation. The aim of our study was to determine the validity and responsiveness of the Knee Society rating system compared with the Short Form-36 health survey (SF-36), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and a four-question 4-point Likert scale satisfaction questionnaire following revision total knee arthroplasty.

METHODS

A total of 152 patients underwent revision total knee arthroplasty at our institution, between August 2003 and January 2007, and had a two-year follow-up evaluation after revision surgery. The SF-36, WOMAC, Knee Society rating system, and satisfaction scores were completed preoperatively and postoperatively. Spearman correlation coefficients were calculated to determine the degree of correlation for each outcome scale. The SF-36, WOMAC, and patient satisfaction were correlated with the Knee Society rating system.

RESULTS

Both before and after surgery, the correlation among items of the Knee Society rating system displayed low to negligible levels of association. The Knee Society rating system pain score showed modest levels of convergent construct validity with the WOMAC and SF-36. However, the Knee Society functional score displayed negligible to low correlation with its WOMAC functional counterpart preoperatively. The Knee Society pain and functional scores, respectively, showed marked and moderate association with satisfaction. The change in the Knee Society pain and functional scores had moderate association with the SF-36 and WOMAC counterparts, except low correlation was displayed between the pain scores for the Knee Society rating system and the SF-36. The Knee Society rating system pain score was found to be the most responsive of the measures with a standardized response mean of 1.6, whereas the Knee Society rating system functional score was found to be the least responsive at 0.7.

CONCLUSIONS

Currently, there is no so-called gold standard that optimally reflects the status of the knee, as well as the patient, prior to and following revision total knee arthroplasty. Ideally, numerous assessment scales should be administered to the patient in order to accurately reflect the patient characteristics for the purpose of academic study, but from a practical standpoint, this may not be feasible. We encourage further research and development of a simple and concise standardized questionnaire for use before and after revision total knee arthroplasty.

Electrocautery of the patellar rim in primary total knee replacement: beneficial or unnecessary?

The management of the patella during total knee replacement is controversial. In some studies the absence of patellar resurfacing results in residual anterior knee pain in over 10% of patients. One form of treatment which may be used in an endeavour to reduce this is circumferential patellar rim electrocautery. This is believed to partially denervate the patella. However, there is no evidence of the efficacy of this procedure, nor do we know if it results in harm.

A retrospective comparative cohort study was performed of 192 patients who had undergone a primary total knee replacement with the porous coated Low Contact Stress rotating platform prosthesis without patellar resurfacing between 2003 and 2007. In 98 patients circumferential electrocautery of the patellar rim was performed and in 94 patients it was not. The two groups were matched for gender and age. The general Oxford Knee Score and the more specific patellar score for anterior knee pain were used to assess patient outcomes a minimum of two years post-operatively.

No statistically significant differences were noted between the groups for either scoring system (p = 0.41 and p = 0.87, respectively). Electrocautery of the patella rim did not improve the outcome scores after primary total knee replacement in our patients.

Secondary resurfacing of the patella in total knee arthroplasty

Anterior knee pain following primary total knee arthroplasty is common and can be difficult to treat satisfactorily. We reviewed 28 consecutive patients (29 knees) who underwent secondary resurfacing of the patella for persistent anterior knee pain and report on the results. Mean follow-up was 28 months (range 12-61) with no cases lost to follow-up. Oxford knee scores, range of motion, the patient's assessment of outcome and overall satisfaction were recorded. Seventeen out of 19 (59%) felt their knee was better following patellar resurfacing, 10 out of 29 (34%) felt it was the same and two out of 29 (7%) felt it was worse. There was a significant improvement in Oxford knee scores (p<0.001) and significant increase in patient satisfaction (p<0.001) following secondary resurfacing. While secondary resurfacing of the patella does not provide the solution for every case of anterior knee pain following total knee joint replacement, in greater than 50% of cases it can be effective at relieving symptoms and in this series carries a low risk of worsening symptoms or complications.

Cost-benefit comparison of the Oxford Knee score and the American Knee Society score in measuring outcome of total knee arthroplasty

The American Knee Society score (AKSS) and the Oxford Knee score (OKS) are validated outcome measures for evaluation of total knee arthroplasties (TKAs). We investigated whether patient self-assessment using the OKS offers a viable alternative to clinical review using the AKSS. Preoperative, 2-year, 5-year, and 10-year postoperative OKS and AKSS were reviewed from TKA patients. The scores were analyzed using the Pearson correlation. There was good correlation of OKS and AKSS at 2 years. This implies that patient self-assessment is a viable screening tool to identify which patients require clinical review, at 2 years, after TKA. However, the moderate correlation at 5 and 10 years indicates that clinical evaluation remains necessary at these time points.

The Knee Arthroplasty Trial (KAT) design features, baseline characteristics, and two-year functional outcomes after alternative approaches to knee replacement

BACKGROUND

The aim of continued development of total knee replacement systems has been the further improvement of the quality of life and increasing the duration of prosthetic survival. Our goal was to evaluate the effects of several design features, including metal backing of the tibial component, patellar resurfacing, and a mobile bearing between the tibial and femoral components, on the function and survival of the implant.

METHODS

A pragmatic, multicenter, randomized, controlled trial involving 116 surgeons in thirty-four centers in the United Kingdom was performed; 2352 participants were randomly allocated to be treated with or without a metal backing of the tibial component (409), with or without patellar resurfacing (1715), and/or with or without a mobile bearing (539). Randomization to more than one comparison was allowed. The primary outcome measures were the Oxford Knee Score (OKS), Short Form-12, EuroQol-5D, and the need for additional surgery. The results up to two years postoperatively are reported.

RESULTS

Functional status and quality-of-life scores were low at baseline but improved markedly across all trial groups following knee replacement (mean overall OKS, 17.98 points at baseline and 34.82 points at two years). Most of the change was observed at three months after the surgery. Six percent of the patients had additional knee surgery within two years. There was no evidence of differences in clinical, functional, or quality-of-life measures between the randomized groups at two years.

CONCLUSIONS

Patients have substantial improvement following total knee replacement. This is the first adequately powered randomized controlled trial, of which we are aware, in which the effects of metal backing, patellar resurfacing, and a mobile bearing were investigated. We found no evidence of an effect of these variants on the rate of early complications or on functional recovery up to two years after total knee replacement.

Can patients help with long-term total knee arthroplasty surveillance? Comparison of the American Knee Society Score self-report and surgeon assessment

OBJECTIVES

To compare patient self-report of knee flexion, extension, range of motion (ROM) and American Knee Society (AKS) Pain, Knee and Functional scores with a clinician assessment.

METHODS

A total of 239 consecutive total knee arthroplasty (TKA) patients (290 knees) were mailed surveys with an AKS questionnaire and lateral knee photographs that showed knee ROM in 10 degrees increments to compare their operated knee(s) ROM. Patients were subsequently seen in clinic and their ROM, AKS Pain, Knee and Functional scores were measured. Patient- and physician-reported measures were compared using independent sample t-test and correlated using Spearman's correlation coefficient. A priori rules for comparisons were based on previously published reports.

RESULTS

A total of 286 knees had both survey and clinic data available and constituted the analytic set. Patient-reported and physician-assessed extension, flexion and ROM were: 3 +/- 4.8 degrees vs 1.4 +/- 4.3 degrees (P < 0.001), 111.4 +/- 14.6 degrees vs 110 +/- 12.8 degrees (P = 0.04) and 108.6 +/- 16.8 vs 108.6 +/- 14.3 degrees (P = 0.98). There was a moderate correlation between patient and physician assessments (extension = 0.31; flexion = 0.44; ROM = 0.42; P < or = 0.001 for all). Patient-reported and physician-assessed AKS Pain, Knee and Functional scores were: 35.8 +/- 15.6 vs 43.9 +/- 11.1 (P < 0.001), 79.8 +/- 20 vs 88.9 +/- 13.3 (P < 0.001) and 57.7 +/- 23.1 vs 65.7 +/- 26.4 (P < 0.001), respectively. Patient- and physician-assessed AKS Pain, Knee and Functional scores had moderate-high correlation (r = 0.49, 0.49 and 0.70; P < or = 0.001 for all).

CONCLUSION

Long-term surveillance of TKA patients may be possible using a self-report AKS, but the average 8- to 10-point difference between patient- and physician-reported AKS scores (patients reporting poorer scores) represents a substantial impact on this outcome instrument. Since patient-reported responses have clear value in global assessment, further evaluation with other validated outcome instruments is warranted.

Does computer navigation in total knee arthroplasty improve patient outcome at midterm follow-up?

Computer navigation assistance in total knee arthroplasty (TKA) results in consistently accurate alignment of prostheses. We aimed to compare the outcome of computer-navigated and conventional TKA and to analyse the radiologically malaligned knees. We analysed 637 primary TKA, carried out by a single surgeon, over five consecutive years and divided them into two cohorts: group 1 = STA (standard instrumentation) and group 2 = CAS (computer-assisted surgery). There was no significant difference between the average Oxford Knee Scores (OKS) of the two groups at any time from one to five years. However, the malaligned TKA at three years had a worse OKS. At medium term there is no difference in clinical outcome measures that can be attributed to the surgeon having used computer-assisted navigation for TKA. But group 1, having a higher proportion of malaligned TKA, might show worsening of OKS at long term.

Towards a standard in assessment of bone cutting for total knee replacement

Arthroplasty outcome is influenced by the ‘quality’ of bone preparation for implant insertion. Surgeons face increasing choices of technique and instrumentation, yet clinical scoring methods assess the overall outcome and patient satisfaction but not the bone cuts directly. ‘Quality management’ of bone reshaping is needed to evaluate different bone cutting methods and computer assisted orthopaedic surgery (CAOS) systems. Analyses and experiments in this study were formulated for measurement and computation of four quantitative characteristics of bone preparation ‘quality’ and produced a highly condensed index for each. These represented (a) surface finish of cuts, (b) implant fit/looseness possible with the cut shape, (c) implant location/misalignment, and (d) accuracy of individual planar cuts. Assessment of synthetic bone cuts verified the robustness of the method for wide application in arthroplasty intraoperatively, in vitro and for comparing navigation systems.

Unicompartmental knee arthroplasty for the treatment of unicompartmental osteoarthritis: a systematic study

Unicompartmental knee arthroplasty (UKA), total knee arthroplasty (TKA) and high tibial osteotomy (HTO) may all be used to treat unicompartmental osteoarthritis, but they are often used for different patient groups. However, there is considerable overlap in indications for all three options. The aim of this review was to assess the safety and efficacy of UKA compared with TKA and HTO in unicompartmental osteoarthritis. Studies that compared UKA with either TKA or HTO were identified and included for review. For knee function and postoperative pain, UKA appeared similar to TKA and HTO at 5 years follow up. Range of motion was better in UKA compared with TKA. Complication rates after UKA and TKA appeared similar, although deep vein thrombosis was reported more often after TKA. There were more complications after HTO than UKA. Survival of UKA prostheses was approximately 85-95%, compared with at least 90% for TKA at 10 years follow up. Survivorship for HTO appeared to be less than 85%. It was not clear whether there were more revisions after UKA than TKA, but there appeared to be fewer revisions in UKA compared with HTO. UKA is considered at least as safe as TKA and HTO. For function, UKA appears to be at least as efficacious as TKA and HTO. The survival of UKA compared with TKA and HTO cannot be determined based on the available evidence.

Computer navigation versus conventional total knee replacement

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.

[The modular MML revision system in knee revision and tumor arthroplasty]

Increasing age and a higher level of mobility lead to an increasing incidence in revision arthroplasty after total knee replacement and tumor surgery. So far, the reconstruction of large defects in bony and soft tissue environments can be accomplished by the modern modular components of revision implants. The consecutive reconstruction of the extensor mechanism in extended revision has its own drawbacks and is often associated with significant functional limitations for the patient. Specially designed implants and methods are required to generate good functional results. The modular knee revision system MML provides specific modifications of the tibial component for reconstruction of the extensor mechanism. Combined with artificial strips, an excellent functional outcome could be achieved. In this study, 70 patients were operated with the MML endoprosthesis in knee revision or tumor surgery. An excellent functional outcome could be determined. At 7 years after surgery, an average of 32+/-13 points was achieved on the Oxford Knee Score. The outcome measurement using the functional scoring system of the American Knee Society (AKS score) showed similarly good results with 71+/-25 points out of 100. A minor deficit of only 2 degrees in active extension could be observed after reconstruction of the extensor mechanism. In conclusion, we have demonstrated that the MML modular revision system is appropriate for reconstruction of segmental bone defects.

Translation and validation of the Dutch version of the International Knee Documentation Committee Subjective Knee Form

BACKGROUND

For knee-related surgery, there is a great demand for internationally useable subjective scoring systems. Before such measurements can be used, they should be translated and validated for the population they are used on. For the Dutch population, only the Western Ontario and McMaster Universities Osteoarthritis Index and Oxford 12 Questionnaire have been validated. However, these scores can only be used regarding osteoarthritis of the knee. In 2001, the International Knee Documentation Committee presented the Subjective Knee Form, which is a knee-specific rather than a disease-specific questionnaire.

STUDY DESIGN

Cohort study (diagnosis/symptom prevalence); Level of evidence, 2.

METHODS

The authors describe the translation procedure and validation of the Dutch Subjective Knee Form. After a forward-backward translation protocol, the reliability, validity, and content validity were tested. The responses of 145 consecutive knee patients on 2 questionnaires containing the Short Form-36, Western Ontario and McMaster Universities Osteoarthritis Index, Oxford 12 Questionnaire score, a visual analog scale, and the Dutch International Knee Documentation Committee Subjective Knee Form were used. Reliability was tested by measuring the test-retest reliability and internal consistency. Validity was tested by correlating the questionnaire to the other outcome measurements, and content validity was tested by measuring the floor and ceiling effects.

RESULTS

The reliability proved excellent with an intraclass coefficient of 0.96 for test-retest. Internal consistency was strong (Cronbach alpha, .92). The construct, convergent, and divergent validities were good. The content validity was good; no floor or ceiling effect occurred.

CONCLUSION

The validation procedure shows that the Dutch International Knee Documentation Committee Subjective Knee Form is an excellent evaluation instrument for Dutch patients with knee-related injuries.

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.

Peri-prosthetic bone mineral density after total knee arthroplasty

We compared peri-prosthetic bone mineral density between identical cemented and cementless LCS rotating platform total knee arthroplasties. Two matched cohorts had dual energy x-ray absorptiometry scans two years post-operatively using a modified validated densitometric analysis protocol, to assess peri-prosthetic bone mineral density. The knee that was not operated on was also scanned to enable the calculation of a relative bone mineral density difference. Oxford Knee and American Knee Society scores were comparable in the two cohorts.

Statistical analysis revealed no significant difference in absolute, or relative peri-prosthetic bone mineral density with respect to the method of fixation. However, the femoral peri-prosthetic bone mineral density and relative bone mineral density difference were significantly decreased, irrespective of the method of fixation, particularly in the anterior distal portion of the femur, with a mean reduction in relative bone mineral density difference of 27%.

There was no difference in clinical outcome between the cemented and cementless LCS total knee arthroplasty. However, both produce stress-shielding around the femoral implants. This leads us to question the use of more expensive cementless total knee components.

A response to issues raised in a recent paper concerning the Oxford knee score

In a recently published paper, authors were critical of the Oxford Knee Score (OKS) patient based measure. We discuss a number of the interesting issues that this paper raised and point out some obvious misunderstandings. The OKS, whilst not perfect, has been shown in independent comparative studies to perform more satisfactorily than other measures. It remains one of a small number of measures with satisfactory measurement properties. It would be a great pity if clinicians were deterred from using the OKS on the basis of comments made in the recent publication.

Superficial incisional infection in arthroplasty of the lower limb

The Department of Health and the Public Health Laboratory Service established the Nosocomial Infection National Surveillance Scheme in order to standardise the collection of information about infections acquired in hospital in the United Kingdom and provide national data with which hospitals could measure their own performance. The definition of superficial incisional infection (skin and subcutaneous tissue), set by the Center for Disease Control (CDC), should meet at least one of the defined criteria which would confirm the diagnosis and determine the need for specific treatment.

We have assessed the interobserver reliability of the criteria for superficial incisional infection set by the CDC in our current practice. The incisional site of 50 patients who had an elective primary arthroplasty of the hip or knee was evaluated independently by two orthopaedic clinical research fellows and two orthopaedic ward sisters for the presence or absence of surgical-site infection. Interobserver reliability was assessed by comparison of the criteria for wound infection used by the four observers using kappa reliability coefficients. Our study demonstrated that some of the components of the current CDC criteria were unreliable and we recommend their revision.

The reliability of hip scoring systems for total hip arthroplasty candidates: assessment by physical therapists

OBJECTIVE

Hip rating systems have been widely used in assessing severity of hip dysfunction but no uniform method has emerged. The current study was performed to determine the interobserver reliability of five different hip scores on patients with coxarthrosis.

DESIGN

Test reliability among physical therapists for five commonly used hip scores.

SUBJECTS

Thirty-five patients (48 hips) who had coxarthrosis and who were candidates for total hip arthroplasty were included in the study.

METHODS

Patients were evaluated preoperatively by three physical therapists using five different hip rating systems; the Harris Hip Score, the Iowa Hip Score, the Charnley Hip Score, the Merle d'Aubigne Hip Score and the American Academy of Orthopaedic Surgeons' Hip Score.

RESULTS

The average age of the patients was 58.8 +/- 2.2 years (range 28-76 years). For all scores, an excellent interobserver reliability between the physical therapists were found (kappa = 0.77-0.95). The best correlation between first and second observer was on Harris Hip Score (kappa = 0.91), between second and third was on Merle d'Aubigne Hip Score (kappa = 0.95) and between first and third was on Iowa Hip Score (kappa = 0.87).

CONCLUSION

There was an excellent interobserver reliability for all hip scores between the physical therapists, suggesting that all these hip scores are suitable for use by physical therapists.

Gait and clinical measurements in patients with knee osteoarthritis after surgery: a prospective 5-year follow-up study

The aim of this prospective follow-up study was to determine if gait measurements and/or clinical measurements could detect differences in treatment outcome between two surgical interventions in patients with knee osteoarthritis (OA). The patients were followed for 5 years after surgery. Forty patients, 55-70 years of age, with unilateral knee OA were included. The patients were treated either with a high tibial osteotomy (HTO) (n=18) or a unicompartmental knee arthroplasty (UKA) (n=22). Clinical outcome measures were the British Orthopaedic Association (BOA) score, pain during walking, passive range of knee motion (PROM) and patients' subjective opinion. The gait variables were free walking speed, step frequency, step length and single and double-stance phase for each leg. The patients were examined before surgery and 3 months, 1 year and 5 years after surgery. The time-distance variables of gait could detect differences in treatment outcome, 3 months after surgery, while the clinical outcome measures, as given here, could not detect any differences between the two groups of patients. Measurements of free walking speed could be recommended for clinical evaluation, after surgical interventions, in patients with knee OA.