Paediatric and adolescent anterior cruciate ligament reconstruction surgery: results from a national cohort of 16,000 patients over 20 years

Aims Anterior cruciate ligament (ACL) surgery in children and the adolescent population has increased steadily over recent years. We used a national database to look at trends in ACL reconstruction and rates of serious complications, growth disturbance, and revision surgery, over 20 years. Methods All hospital episodes for patients undergoing ACL reconstruction, under the age of 20 years, between 1 April 1997 and 31 March 2017, were extracted by procedure code from the national Hospital Episode Statistics (HES). Population standardized rates of intervention were determined by age group and year of treatment. Subsequent rates of serious complications including reoperation for infection, growth disturbance (osteotomy, epiphysiodesis), revision reconstruction, and/or contralateral ACL reconstruction rates were determined. Results Over the 20 year period, 16,125 ACL reconstructions were included. The mean age of patients was 16.9 years (SD 2.0; 27.1% female, n = 4,374/16,125). The majority of procedures were observed in the 15 to 19 years age group. The rate of ACL reconstruction increased 29-fold from 1997 to 1998, to 2016 to 2017. Within 90 days of ACL reconstruction, the rate of reoperation for infection was 0.31% (95% confidence interval (CI) 0.23 to 0.41, n = 50/16,125) and the rate of pulmonary embolism was 0.037% (95%.CI 0.014 to 0.081, n = 6/16,125). Of those with minimum five-year follow-up following ACL reconstruction (n = 7,585), 1.00% of patients subsequently underwent an osteotomy (95% CI 0.79 to 1.25, n = 76/7,585), 0.09% an epiphysiodesis (95% CI 0.04 to 0.19, n = 7/7,585), 7.46% revision ACL reconstruction (95% CI 6.88 to 8.08, n = 566/7,585), and 6.37% contralateral ACL reconstruction (95% CI 5.83 to 6.94, n = 483/7,585). Conclusion Rates of paediatric and adolescent ACL reconstruction have increased 29-fold over the last 20 years. Despite the increasing rate in the younger population, the risk of serious complications, including further surgery for growth disturbance is very low. The results of our study provide a point of reference for shared decision making in the management of ACL injury in the paediatric and adolescent population.</p

Valgus subsidence of the tibial component in cementless Oxford unicompartmental knee replacement

The cementless Oxford unicompartmental knee replacement has been demonstrated to have superior fixation on radiographs and a similar early complication rate compared with the cemented version. However, a small number of cases have come to our attention where, after an apparently successful procedure, the tibial component subsides into a valgus position with an increased posterior slope, before becoming well-fixed. We present the clinical and radiological findings of these six patients and describe their natural history and the likely causes. Two underwent revision in the early post-operative period, and in four the implant stabilised and became well-fixed radiologically with a good functional outcome. This situation appears to be avoidable by minor modifications to the operative technique, and it appears that it can be treated conservatively in most patients. © 2014 The British Editorial Society of Bone and Joint Surgery

New instrumentation system for cementless mobile-bearing unicompartmental knee arthroplasty improves surgical performance particularly for trainees

Background Mobile-bearing medial-unicompartmental knee arthroplasty (mUKA) has a documented learning curve. New instrumentation has been designed with the aim of reducing the technical challenges of this procedure. The primary aim of this study was to evaluate the technical performance of mUKA using new (Microplasty) versus older (Phase III) instrumentation, performed by expert surgeons and trainees. Secondary aims were to evaluate functional outcome and mid-term survivorship. Methods A time-based comparative cohort study was performed between 2009 and 2015 at a high-volume centre. 273 patients (273 knees, 49.5% female) of mean age 67.8 (standard deviation 10.1) years underwent mUKA. 153 (56.0%) procedures used Microplasty instruments and 120 procedures (44.0%) used Phase III instruments. Results Non-optimal bearing usage was less frequent with Microplasty than Phase III instruments (24 knees [15.7%] versus 33 knees [27.5%], p = 0.024), with differences due to improved trainee performance. Femoral component sagittal alignment outliers were less frequent with Microplasty, but this was not statistically significant (9 knees [5.9%] versus 13 knees [10.8%], p = 0.18). Post-operative Oxford Knee Scores (OKS) were better with Microplasty (median 42 points [interquartile range 38–44]) compared to Phase III (median 39.5 points [IQR 33–44]), which was statistically significant (p = 0.023), but not clinically meaningful. The overall 5-year Kaplan-Meier (KM) survival estimate was 99.3% (95% CI 97.0–99.8%), with no differences between Microplasty and Phase III instrumentation. Conclusions New instrumentation improved the reliability of the proximal tibial resection in trainees. Further research is warranted to investigate whether Microplasty instrumentation shortens the learning curve for medial UKA

Valgus subsidence of the tibial component in cementless Oxford unicompartmental knee replacement

The cementless Oxford unicompartmental knee replacement has been demonstrated to have superior fixation on radiographs and a similar early complication rate compared with the cemented version. However, a small number of cases have come to our attention where, after an apparently successful procedure, the tibial component subsides into a valgus position with an increased posterior slope, before becoming well-fixed. We present the clinical and radiological findings of these six patients and describe their natural history and the likely causes. Two underwent revision in the early post-operative period, and in four the implant stabilised and became well-fixed radiologically with a good functional outcome. This situation appears to be avoidable by minor modifications to the operative technique, and it appears that it can be treated conservatively in most patients. © 2014 The British Editorial Society of Bone and Joint Surgery

The management of mobile bearing dislocation in the Oxford lateral unicompartmental knee replacement

This article describes a technique to manage dislocations of mobile bearing lateral unicompartmental knee replacements. When dislocations occur, the bearing usually subluxes medially over the medial wall of the tibial component into the intercondylar notch. By positioning small fragment screws with their heads above the vertical wall, thereby increasing the height of the wall, subsequent dislocations can be prevented. Seven cases treated in this manner are reported, of which one of the seven has redislocated. In the remaining six, their clinical outcomes are comparable to the outcomes of those without dislocations

Five-year results of a randomised controlled trial comparing cemented and cementless Oxford unicompartmental knee replacement using radiostereometric analysis

Background: Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR). The aim of this study was to determine if cementless UKR fixation is as good as cemented by comparing the five-year migration measured radiostereometric analysis (RSA) in a randomised controlled trial. Methods: Thirty-nine patients were randomised to receive either a cemented or a cementless Oxford UKR and were studied at intervals up to five years to assess migration with RSA and radiolucencies with radiographs. Results: During the first year there was a small and significant amount of migration, predominantly in an anterior direction, of both the cemented (0.24 mm, SD 0.32, p = 0.01) and cementless (0.26 mm, SD 0.31, p = 0.00) femoral components. Thereafter there was no significant migration in any direction. At no stage was there any significant difference between the migrations of the cemented or cementless femoral components. During the first year, particularly the first three months, the cementless tibial components subsided 0.28 mm (SD 0.19, p = 0.00). This was significantly (p = 0.00) greater than the subsidence of the cemented tibial component (0.09, SD 0.19, p = 0.28). Between the second and fifth years there was no significant migration of either cemented or cementless tibial components. At five years radiolucent lines occurred significantly less with cementless (one partial) compared to cemented (six partial and one complete) tibial components. Conclusions: As, between two and five years, there was no significant migration of cemented or cementless components, and no significant difference between them, we conclude that cementless fixation is as reliable as cemented. It may be better as there are fewer radiolucent lines.</p

Rationally mispriced assets in equilibrium

Asymmetric information, Rational expectations, Mispricing, Efficiency, D43, D51, D8,