Geert Peersman

Cost-effectiveness of unicondylar versus total knee arthroplasty: a Markov model analysis

BACKGROUND Unicondylar knee arthroplasty (UKA) is believed to lead to less morbidity and enhanced functional outcomes when compared with total knee arthroplasty (TKA). Conversely, UKA is also associated with a higher revision risk than TKA. In order to further clarify the key differences between these separate procedures, the current study assessing the cost-effectiveness of UKA versus TKA was undertaken. METHODS A state-transition Markov model was developed to compare the cost-effectiveness of UKA versus TKA for unicondylar osteoarthritis using a Belgian payers perspective. The model was designed to include the possibility of two revision procedures. Model estimates were obtained through literature review and revision rates were based on registry data. Threshold analysis and probabilistic sensitivity analysis were performed to assess the models robustness. RESULTS UKA was associated with a cost reduction of €2,807 and a utility gain of 0.04 quality-adjusted life years in comparison with TKA. Analysis determined that the model is sensitive to clinical effectiveness, and that a marginal reduction in the clinical performance of UKA would lead to TKA being the more cost-effective solution. CONCLUSION UKA yields clear advantages in terms of costs and marginal advantages in terms of health effects, in comparison with TKA.

The influence of polyethylene bearing thickness on the tibiofemoral kinematics of a bicruciate retaining total knee arthroplasty

BACKGROUND The recently reintroduced bicruciate retaining Total Knee Arthroplasty (BCR TKA) is an effort to reproduce kinematics closer to the native knee. However, there is no data on appropriate balancing with this implant. Balancing is crucial and challenging as medial and lateral polyethylene (PE) inlays are modular, which allows for placement of different thicknesses in the medial and lateral compartments. This study aimed at providing a detailed kinematic view on balancing BCR TKA. METHODS Seven fresh frozen cadaver legs were mounted in a kinematic rig that applied squatting under application of physiologic quadriceps and hamstring forces. Additionally, specimen laxity was assessed using Lachman tests and varus/valgus stress tests. Following testing on the native knee, a BCR TKA was implanted in each specimen and all trials were repeated. Using one millimeter increments, five inlay thicknesses were tested to simulate optimal balancing, symmetric under-, and overstuffing, valgus constellation, and varus constellation. RESULTS Overall, knee kinematics following BCR TKA seem to be very close to the native knee. The changes as introduced to tibiofemoral kinematics through over- or understuffing the polyethylene inserts are affecting the system only to a minor degree and generally lack statistical significance. Reproduction of the tibial varus via PE-Inlays did not lead to kinematics much closer to the native knee. CONCLUSIONS The changes introduced to tibiofemoral kinematics by removal of the conforming meniscus and cartilage and replacement with a flat PE insert and femoral component are of more impact than different inlay sizes and their combinations for a BCR TKA.

Malrotation deformities of the lower extremity and implications on total knee arthroplasty: a narrative review

IntroductionTotal knee arthroplasty (TKA) is a successful procedure for the management of osteoarthritis (OA) of the knee. Axial plane deformities are more common than suspected in patients presenting with osteoarthritis of the knee joint. Recent research has indicated that torsional deformities could play an important role in the development of anterior knee pain (AKP).MethodsIn a narrative review of the literature, the aetiology of maltorsion deformity of the lower extremity in both, childhood and adulthood, as well as the development of postoperative femoral axial plane deformities are examined. This includes the numerous surgical interventions that have been described for the treatment of maltorsion syndrome, and the role of patient-specific instrumentation. Finally, correcting for maltorsion deformity during and its potential implications for the current clinical care pathway, in terms of both pre- and perioperative practices is discussed.Discussion and conclusionAxial plane alignment is considered the ‘third dimension’ in TKA. Correct axial alignment the lower extremity and of prosthetic components is deemed an important prerequisite for a postoperatively stable and painless knee. Identification of and, where appropriate, adjustment for any pre-existing maltorsion deformities is thought to significantly reduce the proportion of patients with residual complaints following TKA. Well-designed and well-conducted clinical studies are required to support our hypotheses.

Custom-made lateral femoral hemiarthroplasty for traumatic bone loss: A case report

We report the case of a 32-year-old male patient involved in a road traffic accident in which he sustained a grade II open supra- and intercondylar fracture of the left distal femur with substantial bone loss of the lateral femoral condyle and trochlea (AO classification type 33 C3). Normal knee function was no longer possible, as the patella was trapped within the bony defect. Existing reconstructive options such as unicondylar osteoarticular allograft, arthrodesis, and arthroplasty were considered. However, as all these techniques present significant disadvantages, particularly in young and active patients, a custom-made lateral hemiarthroplasty was designed and implanted as an alternative treatment. Follow-up at 24 months revealed an excellent, pain-free level of function and radiographs showed no signs of implant loosening or migration. This technique offers the most anatomical means of reconstruction with maximal preservation of the bone stock, thereby better facilitating any revisions that may be necessary in the future. This is an experimental technique reserved for rare indications, and currently has no long-term follow-up results associated with its use. Additional research is therefore needed before widespread adoption of this technique can take place.