A Comprehensive Evaluation of Lateral Unicompartmental Knee Arthroplasty Short to Mid-Term Survivorship, and the Effect of Patient and Implant Characteristics: An Analysis of Data From the Dutch Arthroplasty Register.

BACKGROUND: The rarity of lateral unicompartmental knee arthroplasty (UKA) results in a lack of large cohort studies and understanding. The aim of this study is to comprehensively evaluate survivorship of lateral UKA with registry data and compare this to medial UKA. METHODS: Lateral (n = 537) and medial UKAs (n = 19,295) in 2007-2017 were selected from the Dutch Arthroplasty Register. Survival analyses were performed with revision for any reason as primary endpoint. Adjustments were made for patient and implant characteristics. Stratified analyses according to patient and implant characteristics were performed. Reasons and type of revision were grouped according to laterality and bearing design. RESULTS: The 5-year revision rate was 12.9% for lateral UKA and 9.3% for medial UKA. Multivariable regression analyses showed no significant increased risk for revision for lateral UKA (hazard ratio 0.87, 95% confidence interval 0.66-1.15). Stratified analyses showed that the effect of patient characteristics on revision was comparable between lateral and medial UKA; however, the use of mobile-bearing design for lateral UKA was associated with increased revision rate. Progression of osteoarthritis was the main reason for revision on both sides accompanied by tibia component loosening for medial UKA. Reasons and type of revision varied depending on bearing design. CONCLUSION: Similar survivorship of lateral and medial UKA was reported. Specifically, there is a notable risk for revision when using mobile-bearing designs for lateral UKA. Failure modes and type of revision depends on laterality and bearing design. These findings emphasize that surgical challenges related to anatomy and kinematics of the lateral and medial knee compartment need to be considered.

Bearing design influences short- to mid-term survivorship, but not functional outcomes following lateral unicompartmental knee arthroplasty: a systematic review.

PURPOSE: To determine survivorship and functional outcomes of fixed and mobile-bearing designs in lateral unicompartmental knee arthroplasties (UKA). METHODS: Medline, EMBASE and Cochrane databases were searched. Annual revision rate and functional outcomes were assessed for both fixed and mobile-bearing designs. RESULTS: A total of 28 studies, of which 19 fixed-bearing and 9 mobile-bearing, representing 2265 lateral UKAs were included for survivorship and functional outcome analyses. The mean follow-up of fixed and mobile-bearing studies was 7.5 and 3.9 years, respectively. Annual revision rate of fixed-bearing designs was 0.94 (95% CI 0.66-1.33) compared to 2.16 (95% CI 1.54-3.04) for mobile-bearing. A subgroup analysis of the domed shaped mobile-bearing design noted an annual revision rate of 1.81 (95% CI 0.98-3.34). Good-to-excellent functional outcomes were observed following fixed and mobile-bearing lateral UKAs; no significant differences were found. CONCLUSION: Mobile-bearing lateral UKAs have a higher rate of revision compared to fixed-bearing lateral UKAs with regard to short- to mid-term survivorship; however, the clinical outcomes are similar. Despite the introduction of the domed shaped mobile-bearing design, findings of this study suggest fixed-bearing implant design is preferable in the setting of isolated lateral osteoarthritis (OA). This systematic review was based on low to moderate evidence, therefore, future registry data are needed to confirm these findings. However, this study included a large number of patients, and could provide information regarding risk of revision and functional outcomes of mobile and fixed-bearing type lateral UKA. LEVEL OF EVIDENCE: IV.

Favourable results of a new intraoperative and postoperative filtered autologous blood re-transfusion system in total hip arthroplasty: a randomised controlled trial.

PURPOSE: A new intraoperative filtered salvaged blood re-transfusion system has been developed for primary total hip arthroplasty (THA) that filters and re-transfuses the blood that is lost during THA. This system is intended to increase postoperative haemoglobin (Hb) levels, reduce perioperative net blood loss and reduce the need for allogeneic transfusions. It supposedly does not have the disadvantages of intraoperative cell-washing/separating re-transfusion systems, such as extensive procedure, high costs and need for specialised personnel. To re-transfuse as much as blood as possible, postoperatively drained blood was also re-transfused. METHODS: A randomised, controlled, blinded, single-centre trial was conducted in which 118 THA patients were randomised to an intraoperative autologous blood re-transfusion (ABT) filter system combined with a postoperative ABT filter unit or high-vacuum closed-suction drainage. RESULTS: On average, 577 ml of blood was re-transfused in the ABT group: 323 ml collected intraoperatively and 254 ml collected postoperatively. Hb level was higher in the ABT vs the high-vacuum drainage group: 11.4 vs. 10.8 g/dl, p = 0.02 on day one (primary endpoint) and 11.0 vs. 10.4 g/dl, p = 0.007 on day three. Total blood loss was less in the autotransfusion group: 1472 vs. 1678 ml, p = 0.03. Allogeneic transfusions were needed in 3.6 % of patients in the ABT group and 6.5 % in the drainage group, p = 0.68. CONCLUSION: The use of a new intraoperative ABT filter system combined with a postoperative ABT unit resulted in higher postoperative Hb levels and less total blood loss compared with a high-vacuum drain following THA.

Postoperative autologous blood transfusion drain or no drain in primary total hip arthroplasty? A randomised controlled trial.

PURPOSE: Postoperative maintenance of high haemoglobin (Hb) levels and avoidance of homologous blood transfusions is important in total hip arthroplasty (THA). The introduction of a postoperative drainage autologous blood transfusion (ABT) system or no drainage following THA has resulted in reduction of homologous blood transfusion requirements compared with closed-suction drains. The purpose of this study was to examine which regimen is superior following THA. METHODS: A randomised controlled blinded prospective single-centre study was conducted in which 100 THA patients were randomly allocated to ABT or no drainage. The primary endpoint was the Hb level on the first postoperative day. RESULTS: The postoperative collected drained blood loss was 274 (±154) ml in the ABT group, of which 129 (±119) ml was retransfused (0-400). There was no statistical difference in Hb levels on the first postoperative day (ABT vs no drainage: Hb 11.0 vs 10.9 g/dl), on consecutive days (day 3: Hb 10.7 vs 10.2, p = 0.08) or in total blood loss (1,506 vs 1,633 ml), homologous transfusions, pain scores, Harris Hip Score, SF-36 scores, length of hospital stay or adverse events. CONCLUSIONS: The use of a postoperative autologous blood retransfusion drain did not result in significantly higher postoperative Hb levels or in less total blood loss or fewer homologous blood transfusions compared with no drain.

Autologous platelet gel in total knee arthroplasty: a prospective randomized study.

PURPOSE: Total knee arthroplasty (TKA) is often associated with major postoperative blood loss, postoperative pain, and impaired wound healing. The application of autologous platelet gel (APG), prepared from the buffy coat of a unit of autologous blood, has been advocated to improve haemostasis after surgery, to decrease perioperative blood loss, diminish postoperative pain and to enhance the wound healing process. This randomized controlled pilot study was developed to assess the effects of APG after total knee arthroplasty on blood loss, wound healing, pain, range of motion, and hospital stay. METHOD: A prospective, randomized observer blind controlled trial was performed. Forty patients with only osteoarthritis of the knee were scheduled to have a TKA, and they were randomized into two groups. Patients in the treatment group were all treated with the application of autologous platelet gel after the prosthesis was implanted. Patients in the control group were treated with the same protocol but no APG was used. RESULTS: Preoperative and postoperative Hb levels showed no significant difference and allogenic blood transfusions were not given in either group. Haematomas were significantly larger in the control group than in the platelet gel group (P = 0.03). The pain score at rest was higher in the control group on the 3rd day (P = 0.04). Wound healing disturbances were seen in four patients in the control group and in no patients in the APG group (n.s.). Range of motion of the knee was similar postoperatively. Hospital stay was 6.2 days in the APG and 7.5 days in the control group (n.s.). CONCLUSION: In this prospective randomized pilot study on APG in total knee arthroplasty, differences in favour of the use of platelet gel were found, but these were subjective evaluations, marginal in effect, or did not reach statistical significance. The use of drains might have decreased the concentration of delivered platelets and may have diminished the effect. However, in this study, a statistically significant clinically important effect in favour of platelet gel application was not found. Further studies with larger numbers of patients, and without the use of drains, are warranted to investigate the possible benefits of autologous platelet gel in total knee arthroplasty.

A new CT scan method for measuring the tibial tubercle trochlear groove distance in patellar instability.

Patellar malalignment leading to objective or potential patella instability can be caused by tibial tuberosity lateralisation. This can be treated with a tuberosity medialisation. CT scan measurements are needed to assess the tibial tubercle trochlear groove distance. When using the previously described methods to determine this distance it can be difficult to determine the anatomical structures on the maximum intensity projection images, and this can lead to measurement error. This study was designed to compare the reliability of a new computer based CT measurement to the previously described method to determine the tibial tubercle trochlear groove distance. For each method, four observers measured each of 50 knees twice. The inter- and intra-observer variability for the conventional method and a new method were determined. Using the conventional method, the number of knees for which the difference between the aggregate mean of all eight measurements and the mean of duplicate measurements per observer greater than 2 mm varied among the observers between 7 and 24 for the 50 knees, while this variation between four and seven for the same 50 knees using the new method. The limits of reproducibility based on measurements from the four different observers improved by 25%, indicating that the measurement error is considerably smaller with the new method. We advise using this more accurate method to improve the selection of patients for a tuberosity medialisation.