Ten-year survival and patient-reported outcomes of a medial unicompartmental knee arthroplasty incorporating an all-polyethylene tibial component.

INTRODUCTION: Biomechanical studies have suggested that proximal tibial strain is elevated in UKAs incorporating all-polyethylene tibial components with concern that this leads to premature failure. This study reports minimum 10-year outcomes for a UKA incorporating an all-polyethylene tibial component to determine whether these concerns were realised. MATERIALS AND METHODS: 109 fixed bearing UKAs (97 patients, mean age 68 (range 48-87), 54/97 (56%) female) with all-polyethylene tibial components were followed up for ≥ 10 years with Oxford Knee Scores, Forgotten Joint Scores and Kaplan-Meier analysis. 106/109 implants were 7 mm, 3 were 9.5 mm. RESULTS: Ten-year survival was 85.5% (78.6-92.4 95% CI) with the end-point failure for any reason. Unexplained pain was the commonest mode of failure (6/17) followed by lateral compartment osteoarthritis (5/17) and tibial subsidence/loosening (4/17). Revision rate was highest at 2-5 years due to revisions for unexplained pain. Ten-year survival was worse in patients < 65 years old (p = 0.035), in those with BMI > 30 (p = 0.017) and in those with postoperative increases in medial tibial sclerosis (p < 0.001 log-rank). Implant malalignment was not significantly associated with failure. Radioisotope bone scans in 16 patients all remained "hot" at mean 6.1 years (range 2.1-11.5). Relative risk of failure in patients < 65 years was 2.9 (1.2-7.0 95% CI) and when BMI > 30 was 2.9 (1.2-6.9 95% CI). In those with intact UKAs at 10 years, mean Oxford Knee Score was 34.8 ± 10.7, Forgotten Joint Score was 37.9 ± 26.7 and 96% were satisfied with their knee. CONCLUSION: The high rate of early failure between 2 and 5 years in this all-polyethylene tibial component UKA did not persist in the long term. Though medial proximal tibial metabolic changes appear to persist they are not necessarily symptomatic. BMI > 30 and age < 65 years were significant risk factors for revision.

Changes in Bone Density in Metal-Backed and All-Polyethylene Medial Unicompartmental Knee Arthroplasty.

BACKGROUND: Proximal tibial strain in medial unicompartmental knee arthroplasty (UKA) may alter bone mineral density and cause pain. The aims of this retrospective cohort study were to quantify and compare changes in proximal tibial bone mineral density in metal-backed and all-polyethylene medial UKAs, correlating these with outcome, particularly ongoing pain. METHODS: Radiographs of 173 metal-backed and 82 all-polyethylene UKAs were analyzed using digital radiograph densitometry at 0, 1, 2, and 5 years. The mean grayscale of 4 proximal tibial regions was measured and converted to a ratio: the GSRb (grayscale ratio b), where GSRb>1 represents relative medial sclerosis. RESULTS: In both implants, GSRb reduced significantly to 1 year and stabilized with no differences between implants. Subgroup analysis showed less improvement in Oxford Knee Score in patients whose GSRb increased by more than 10% at 1 year (40/255) compared with patients whose GSRb reduced by more than 10% at both 1 years (8.2 vs 15.8, P=.002) and 5 years (9.6 vs 15.8, P=.022). Patients with persistently painful UKAs (17/255) showed no reduction in GSRb at 1 year compared with a 20% reduction in those without pain (P=.05). CONCLUSIONS: Bone mineral density changes under medial UKAs are independent of metal backing. Medial sclerosis appears to be associated with ongoing pain.

Short Term Recovery of Function following Total Knee Arthroplasty: A Randomised Study of the Medial Parapatellar and Midvastus Approaches.

This pilot double blind randomised controlled study aimed to investigate whether the midvastus (MV) approach without patellar eversion in total knee arthroplasty (TKA) resulted in improved recovery of function compared to the medial parapatellar (MP) approach. Patients were randomly allocated to either the MV approach or the MP approach. Achievements of inpatient mobility milestones were recorded. Knee kinematics, muscle strength, Timed Up and Go, WOMAC, and daily step count were assessed before and up to six months after surgery. Cohen's effect size d was calculated to inform the sample size in future trials. Twenty-eight participants (16 males, 12 females) participated. Patient mobility milestones such as straight leg raise were achieved on average 1.3 days (95% CI -3.4 to 0.7, d = 0.63) earlier in the MV group. Knee extensor strength at 6 weeks after surgery was higher (95% CI -0.38 to 0.61, d = 0.73) in the MV group. No trends for differences between the groups were observed in knee kinematics, TUG, WOMAC, or step count. Our results suggest a short term advantage in the first 6 weeks after surgery of the MV approach over the MP approach, but a larger study is required to confirm these findings. This trial is registered with NCT056445.

Variation in physical development in schoolboy rugby players: can maturity testing reduce mismatch?

OBJECTIVES: This study set out to pursue means of reducing mismatch in schoolboy rugby players. The primary objective was to determine whether application of previously reported thresholds of height and grip strength could be used to distinguish those 15-year-old boys appropriate to play under-18 school rugby from their peers. A secondary objective was to obtain normative data for height, weight and grip strength and to assess the variation within that data of current schoolboy rugby players. DESIGN: Cross-sectional cohort study. SETTING: 3 Scottish schools and 'Regional Assessment Centres' organised by the Scottish Rugby Union. PARTICIPANTS: 472 rugby playing youths aged 15 years (Regional Assessment Centres) and 382 schoolboys aged between 12 and 18 years (three schools). OUTCOME MEASURES: Height, weight and grip strength. RESULTS: 97% of 15-year-olds achieved the height and grip strength thresholds based on previous reported values. Larger mean values and wide variation of height, weight and grip strength were recorded in the schoolboy cohort. However, using the mean values of the cohort of 17-year-olds as a new threshold, only 7.7% of 15-year-olds would pass these thresholds. CONCLUSIONS: Large morphological variation was observed in schoolboy rugby players of the same age. Physical maturity tests described in earlier literature as pre-participation screening for contact sports were not applicable to current day 15-year-old rugby players. New criteria were measured and found to be better at identifying those 15-year-old players who had sufficient physical development to play senior school rugby.

Iliac artery pseudoaneurysm rupture following excision of an infected hip prosthesis.

We report a case of external iliac artery aneurysm rupture during removal of the acetabular component for septic loosening. Potentially fatal hemorrhage would have occurred if the risk had not been recognized, and the external iliac vessels exposed to gain vascular control before proceeding with implant removal. A review of the literature on vascular injury at revision hip surgery is presented.

Range of flexion after primary TKA: the effect of soft tissue release and implant design.

Range of motion following total knee arthroplasty (TKA) is a crucial measure of clinical outcome. The purpose of this randomized, controlled study was to determine which factors are predictive of postoperative range of flexion. Fifty-six patients received either a standard or a high-flexion design NexGen Legacy Posterior-Stabilized TKA (Zimmer, Warsaw, Indiana). The relationship between preoperative flexion, intraoperative flexion, and range of flexion 1 year postoperatively was determined. The influence of soft tissue release and the type of femoral component was also investigated. A significant correlation existed between preoperative flexion, intraoperative flexion, and maximum flexion 1 year postoperatively. Patients who had a preoperative range of flexion less than the mean range of flexion for the overall group gained flexion, whereas patients with a preoperative range of flexion greater than the mean range of flexion lost flexion. The degree of soft tissue release performed and the type of implant used had no influence on maximum flexion at 1 year. The principal predictive factor of postoperative range of flexion, regardless of the degree of soft tissue release or implant design, is the preoperative and intraoperative range of flexion.

Is arthroscopic surgery a beneficial treatment for knee osteoarthritis?

Considering the high prevalence of knee osteoarthritis and the relatively common use of arthroscopy to treat this condition, few well-designed studies have been published on the effectiveness of arthroscopy for treating knee osteoarthritis. The study by Kirkley et al. is a welcome addition to the literature as it addresses many of the criticisms of previous work by using appropriate exclusion criteria, standardizing treatment in the study groups, using well-validated clinical scores, and providing a period of follow-up exceeding 2 years. The authors conclude that although all patients benefited from active treatment for knee osteoarthritis, comprising rehabilitation and optimized medical treatment, the addition of arthroscopic debridement of the knee did not improve outcomes. These results underline the outcome of a previous prospective, randomized trial, which concluded that the placebo effect of performing knee arthroscopy for osteoarthritis accounted for the main therapeutic benefit observed at follow-up.

Evidence based factors influencing outcome of arthroscopy in osteoarthritis of the knee.

Arthroscopy continues to be widely used in the management of knee osteoarthritis despite concerns regarding its effectiveness. The Scottish Arthroplasty Project has demonstrated a three-fold variation in rates of arthroscopy for osteoarthritis of the knee across different regions of Scotland. This has clear ramifications for the utilisation of finite health care resources. In light of such variations in national clinical practice this review identifies the evidence based factors which permit identification of patients who will obtain sustained benefit from arthroscopic treatment of knee osteoarthritis. Such a patient should have symptoms of short duration affecting the medial compartment of the knee, have localised tenderness at the medial joint line, mechanical symptoms and positive findings on meniscal stress testing. There should be neither significant mechanical malalignment nor flexion contracture, there should be preservation of the joint space on radiographs and the patient should not be obese. If these criteria are fulfilled the likelihood for long lasting reduction in symptoms is increased.

Knee kinematics in functional activities seven years after total knee arthroplasty.

BACKGROUND: Detailed knowledge of knee kinematics during functional activities is lacking in current studies on the long-term outcome of total knee replacement surgery. The aim of this study was to assess functional knee kinematics using flexible electrogoniometry in patients seven years after unilateral primary total knee arthroplasty for osteoarthritis. METHODS: The knee joint functional movement of a cohort of patients (n=19) with knee osteoarthritis was assessed using electrogoniometry before surgery and 18-24 months and seven years after total knee surgery. The mean age of the patients (11 women and 8 men) at the time of the pre-surgery assessment was 67 years old (SD 8.0). Patient function was also assessed using the Knee Society Score and WOMAC osteoarthritis Index. FINDINGS: The function components of the Knee Society and WOMAC scores were significantly decreased at seven years compared to 18-24 months after surgery (both P<0.05). However, the majority of the functional knee flexion values derived from electrogoniometry did not decrease. Seven years after surgery, knee excursion during ascending and descending stairs was significantly improved compared to 18-24 months after surgery (both P<0.01). INTERPRETATION: The finding that functional knee motion continues to improve between 18-24 months and seven years post-surgery is of interest to both patients and those responsible for their treatment planning. Further, it was shown that the WOMAC and Knee Society Scores do not follow the same trends as the patients' functional knee kinematics seven years after total knee replacement surgery.

The effect of patella resurfacing in total knee arthroplasty on functional range of movement measured by flexible electrogoniometry.

BACKGROUND: The need for patella resurfacing remains an area of considerable controversy in total knee replacement surgery. There would appear to be no reported evidence on the effect of patella resurfacing on knee function, as measured by functional range of movement used in a series of tasks, in patients undergoing knee replacement. The object of this study was to measure knee joint motion during functional activities both prior to and following total knee replacement in a randomised group of patients with and without patella resurfacing and to compare these patient groups with a group of normal age-matched subjects. METHODS: The study design was a double blinded, randomised, prospective, controlled trial. The knee joint functional ranges of movement of a group of patients (n=50, mean age=70 years) with knee osteoarthritis were investigated prior to and following total knee arthroplasty (4 months and 18-24 months) along with a group of normal subjects (n=20, mean age=67). Patients were randomly allocated into two groups, those who received patella resurfacing (n=25) and those who did not (n=25). Flexible electrogoniometry was used to measure the flexion-extension angle of the knees with respect to time in eleven functional activities. FINDINGS: No statistically significant differences (alpha level 0.05) in joint excursion of the affected knee were found between patients who received patella resurfacing and those who did not. INTERPRETATION: Routine patella resurfacing in a typical knee arthroplasty population does not result in an increase in the functional range of movement used after knee replacement.

Knee joint functional range of movement prior to and following total knee arthroplasty measured using flexible electrogoniometry.

The functional ranges of movement of the knee were investigated in a group of patients with knee osteoarthritis (n = 42, mean age 70 years) before, 4 months and at 18-24 months after total knee arthroplasty and then compared with age matched normal subjects (n = 20, mean age 67 years). Flexible electrogoniometry was used to record the maximum flexion-extension angle, the minimum flexion-extension angle and flexion-extension excursions of both knees during eleven functional activities along with the active and passive knee joint range of motion measured using a manual goniometer. Over the eleven functional activities the patients pre-operatively exhibited 28% less knee joint excursion than normal age matched subjects. By 18-24 months following total knee arthroplasty only 2% of this deficit was recovered. Statistically this recovery was only significant in level walking, slope ascent and slope descent. A greater range of movement was measured in a non-weight bearing position than was used in weight bearing functional activity. It is concluded that total knee arthroplasty gives rise to little improvement in knee motion during functional activities and that functional range of movement of the knee remains limited when compared to normal knee function for a minimum of 18 months following operation.