Different Kinematics of Knees with Varus and Valgus Deformities.

Few data exist of kinematics of knees with varus and valgus deformities combined with osteoarthritis. The purpose of this study was to reveal different (1) tibiofemoral kinematics, (2) medial and lateral gaps, and (3) condylar liftoff of osteoarthritic knees with either varus or valgus deformity before and after total knee arthroplasty (TKA). For this purpose, 40 patients for TKA were included in this study, 23 knees with varus deformity and 17 knees with valgus deformity. All patients underwent computer navigation, and kinematics was assessed before making any cuts or releases and after implantation. Osteoarthritic knees with valgus deformity showed a significant difference in tibia rotation relative to the femur with flexion before and after TKA, whereas knees with varus deformity did not. Knees with a valgus deformity showed femoral external rotation in extension and femoral internal rotation in flexion, whereas knees with a varus deformity revealed femoral internal rotation in extension and femoral external rotation in flexion. In both groups, gaps increased after TKA. Condylar liftoff was not observed in the varus deformity group after TKA. In the valgus deformity group, condylar liftoff was detected after TKA at knee flexion of 50 degrees and more. This study revealed significant differences in tibiofemoral kinematics between osteoarthritic knees with a varus or valgus deformity before and after TKA. Valgus deformities showed a paradoxic movement pattern. These in vivo intraoperative results need to be confirmed using fluoroscopic or radiographic three-dimensional matching before and after TKA.

Postural Stability after Unicondylar Knee Arthroplasty and Patient-Specific Interpositional Knee Spacer.

Purpose and Hypothesis. Knee osteoarthritis results, inter alia, in decreased postural stability. After arthroplasty, postural stability recovers, but it is unclear whether this can be ascribed to a reduction of pain or to the preserving of receptor-rich intraarticular soft tissue and natural knee kinematics. The objective of this study was to evaluate whether an unicondylar knee arthroplasty provides better results regarding postural stability or a patient-specific knee spacer. Methods. In this comparative study, we assessed functional results and postural stability 16 months after 20 unicondylar knee arthroplasties (group A) and 20 patient-specific interpositional knee device implantations (group B). Patients were evaluated using the KSS and WOMAC score. Postural stability was analysed during single leg stance on a force platform (Biodex Balance System). Results. Concerning postural stability, range of motion (ROM), and KSS 16 months after the procedure, there were no significant differences between both groups. Conclusion. Successful treatment of knee osteoarthritis restores postural stability to the level of the contralateral side, regardless of the implant device.

Periarticular injections with continuous perfusion of local anaesthetics provide better pain relief and better function compared to femoral and sciatic blocks after TKA: a randomized clinical trial.

PURPOSE: Combined femoral and sciatic nerve blocks for post-operative pain management following total knee arthroplasty (TKA) improve patient satisfaction, decrease narcotic consumption and improve pain. However, accompanying motoric weakness can cause falls and related complications. We wonder whether peri-capsular injections in combination with intra-articular perfusion of local anaesthetics would result in equal or less pain without the related complications of nerve blocks. The objective of the study was to verify these aspects in a prospective randomized trial comparing both treatments. METHODS: Fifty TKA patients randomly received either a femoral (continuous) and a sciatic (single-shot) nerve block (CFNB group, 25 knees) or periarticular infiltrations and a continuous post-operative intra-articular infusion (PIAC group, 25 knees). VAS for pain, pain medication consumption, functional assessment, straight leg raising as well as KSS were recorded post-operatively for 6 days. RESULTS: VAS (p < 0.001) and KSS (p = 0.05) were significantly better for PIAC. There was increased pain following CFNB compared to PIAC. Catheters stayed for 4 days, a pain 'rebound' occurred after removing in CFNB but not after PIAC. There was no difference in regard to knee function (n.s.), but straight leg raising was significant better following PIAC. There were two falls in patients with CFNB. CONCLUSION: Peri-capsular injections combined with an intra-articular catheter provide better pain control, no rebound pain with better function and might decrease the risk of complications related to motor weakness. LEVEL OF EVIDENCE: I.

Prospective single-arm, multi-center trial of a patient-specific interpositional knee implant: early clinical results.

BACKGROUND: The treatment of unicompartmental arthritis in younger patients is challenging. The aim of this study is to report final safety and efficacy analysis results for the iForma patient-specific interpositional device, which is designed for the treatment of isolated medial or lateral compartment arthritis of the knee. METHODS: From June 2005 to June 2008 78 subjects (42 men, 36 women) received an iForma implant. The mean age was 53 years, the mean Body Mass Index 29.0. We surveyed the WOMAC scores, the visual analog pain scale and the Knee Society Scores. RESULTS: The mean follow up was 16.4 months. The mean WOMAC knee scores increased from 48.3 before surgery to 71.3 after 24 months. A reduction in pain was achieved for all five pain measures using a standard visual analog scale (VAS). Knee Society Knee Score improved from 39.2 before to 61.9 24 month after surgery. The Knee Society Function Scores improved form preoperative 64.5 to 82.5 2 years postoperative. The preoperative range of motion could be restored. The overall revision rate was 24%. 15 implants were removed early, 4 knees were revised without implant removal. CONCLUSION: Within narrow indication of patients with unicompartmental disease, the iForma device can provide improvement in knee function and reduction in pain, however, with a significant higher risk of early revision compared to traditional arthroplasty. Respecting this limitation it may be an alternative option for arthritic patients with unicompartmental disease who have contraindications to High Tibial Osteotomy or are too young for knee replacement; the iForma device further has the distinct advantage of time and cost saving compared to those procedures.