In the Irish orthopaedic unit 42 consecutive hip and knee arthroplasty patients from a single consultant were included. There were 26 women and 16 men with average age of 63.9 years (range 36 to 88 years). The average LOS was 6.5 days (range, 3 to 10 days), with 24 patients going to a rehabilitation facility and 18 directly home. There was no correlation found between LOS and either comorbidities, social factors or complications, in both groups although one patient had a delayed discharge due to haematoma and wound drainage in the US. Prolonged LOS in both groups was correlated with delays in rehabilitation bed and transportation availability, reported short staffing in hospital and weekend stays. Both groups were well matched for comparison. The average shorter LOS noted in the US unit appears to be almost entirely attributable to an implemented perioperative care pathway and a more proactive coordinated approach to discharge planning.
As the numbers of revision total knee arthroplasty (RTKA) rise, we continually need current information regarding the etiology/modes of failure and functional disability of patients presenting for RTKA. We used a prospective cohort study to assess these fundamental aspects of RTKA. 290 consecutive subjects presenting for RTKA had relevant clinical information, including modes of failure, collected from surgeon-completed documents. Patients themselves also completed quality of life and functional questionnaires, including the SF-36 and WOMAC Osteoarthritis Index. Mean patient age was 68.6 years (55 to 79 years). Mean SF-36 and WOMAC score at baseline indicated significant functional disability. The mean time from primary procedure to RTKA was 7.9 years (6 months to 27 years). Our series included 31 percent ‘early’ (under 2 years) revisions and 69 percent ‘late’ revisions. Sepsis was the cause of 10.4 percent revisions. The tibia needed revision in 78 percent, femur in 71 percent and patella in 31 percent of cases. The predominant modes of failure (non-exclusive frequency values as patients could have more than one cause) were (in percentages): instability (28.9), malalignment (27.5), tibial osteolysis (27.5), polyethylene wear (24.5), femoral osteolysis (22.5) and tibial loosening (22.2). These patients are relatively young, and considerably disabled by their failed primary procedure. Many modes of failure are within surgical control and direct us toward improved techniques and approaches. Other modes confirm the need for continued development of implants and materials. Information gained here will allow better formulation of measures and resource allocation that may prevent RTKAs.
The requirement for release of collateral ligaments to achieve a stable, balanced total knee replacement has been reported to arise in about 50% to 100% of procedures. This wide range reflects a lack of standardised quantitative indicators to determine the necessity for a release. Using recent advances in computerised navigation, we describe two navigational predictors which provide quantitative measures that can be used to identify the need for release. The first was the ability to restore the mechanical axis before any bone resection was performed and the second was the discrepancy in the measured medial and lateral joint spaces after the tibial osteotomy, but before any femoral resection. These predictors showed a significant association with the need for collateral ligament release (p <
0.001). The first predictor using the knee stress test in extension showed a sensitivity of 100% and a specificity of 98% and the second, the difference between medial and lateral gaps in millimetres, a sensitivity of 83% and a specificity of 95%. The use of the two navigational predictors meant that only ten of the 93 patients required collateral ligament release to achieve a stable, neutral knee.
This study (n=126, mean age=68.8 years, males=62) evaluated pre-operative WOMAC pain and physical function, age, gender, general health status, revision severity classification, number of revisions, comorbidity and unilateral vs. bilateral surgery as predictors of WOMAC pain and physical function at twenty-four months post revision hip arthroplasty. Pain improved from 9.3 to 3.6 and physical function improved from 35.4 to 17.1. No factors were predictive of patient function. Decreased pain was predicted by less pain pre surgery (p=0.01) and being male (p=0.04). To determine if pre-operative WOMAC pain and physical function, age, gender, general health status (SF-36), revision severity classification, number of revisions, comorbidity and unilateral vs. bilateral surgery are predictive of WOMAC pain and physical function at twenty-four months post revision hip arthroplasty. Physical function at twenty-four months is not independently predicted by the pre-treatment factors evaluated in this study. Male patients with less pain pre surgery and little comorbidity have less pain post surgery. With the exception of pre-treatment pain, the pre-treatment factors tested in this study provide minimal guidance in identifying factors that might be modified to enhance patient outcome. This prospective cohort study included one hundred and twenty-six patients (mean age=68.8 years, males: females=62:64) who had revision for other than infection or peri-prosthetic fracture. On average from pre-surgery to twenty-four months post-surgery, WOMAC pain improved 9.3 to 3.6 and physical function improved from 35.4 to 17.1. In univariate analysis (t-test, p<
0.05), males tended to have better function (19.6 vs. 14.7) and reported less pain (4.4 vs. 2.8). No other factors were significant in univariate analysis. None of the a priori factors noted above were independently predictive of patient function at twenty-four months in the multivariate model (F=2.06, p=0.04, R2=0.16). Decreased pain with activity at twenty-four months independently was predicted by having less pain pre surgery (p=0.01), being male (p=0.04) and having fewer comorbidities (p=0.07) in the multi-variate model (F=2.9. p=0.004, R2=0.21).
Although conventional thinking and teaching have implicated weight and body mass index (BMI) in premature failure of total knee arthroplasty (TKA) there is scant evidence based confirmation of this belief. Furthermore, there is little knowledge regarding the precise effect of BMI on functional outcomes following TKA. We performed this study to assess the effect of weight on the longevity of TKA and on outcomes following TKA revision (TKAR). 186 consecutive subjects undergoing TKAR in a 17-center prospective cohort study, had data collected on weight (pounds), BMI and time elapsed between primary and revision surgery (T). The Physical Component Score (PCS) of the Short Form-36 (SF-36), the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index, and the Knee Society Score (KSS) were also collected preoperatively and at 6-month follow-up. Univariate, bivariate and multivariate statistical methods were used in the analysis. The mean BMI and weight were 31.8 (54% of subjects had a BMI >
30) and 200 pounds (range 107–350) respectively. The distribution of both measures of excessive weight was close to normal. Average time between primary and revision procedures (T) was 7.3 years (range 6 months to 27 years). Using linear regression, T significantly decreased as weight (BMI) increased. Mean SF-36 PCS, WOMAC and KSS-Function scores were significantly improved 6 months after revision surgery. However, BMI and, in particular, weight were predictive of worse physical functional outcomes. This study demonstrates the deleterious effect of weight on both the longevity of primary TKA as assessed at the time of revision and on functional outcomes following TKAR. Although further prospective data regarding this population is indicated, the current findings direct us towards better outcomes prediction for overweight patients and more effective counselling and appropriate management of these patients.