Total or Partial Knee Arthroplasty Trial - TOPKAT : study protocol for a randomised controlled trial

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Fracture of the tibial baseplate in bicompartmental knee arthroplasty

Introduction. Bicompartmental knee arthroplasty (BKA) addresses combined medial and patellofemoral compartment osteoarthritis, which is relatively common, and has been proposed as a bridge between unicompartmental and total knee arthroplasty (TKA). Case Presentation. We present the case report of a young active man treated with BKA after unsuccessful conservative therapy. Four years later, loosening with fracture of the tibial baseplate was identified and the patient was revised to TKA. Discussion. Although our case is only the second fractured tibial baseplate to be reported, we believe that the modular titanium design, with two fixation pegs, is too thin to withstand daily cyclic loading powers. Light daily routine use, rather than high-impact sports, is therefore advised. Failures may also be related to the implant being an early generation and known to be technically complex, with too few implant sizes. We currently use TKA for the treatment of medial and patellofemoral compartment osteoarthritis

Popliteus impingement after TKA may occur with well-sized prostheses

To determine the mechanisms and extents of popliteus impingements before and after TKA and to investigate the influence of implant sizing. The hypotheses were that (1) popliteus impingements after TKA may occur at both the tibia and the femur, and (2) even with an apparently well-sized prosthesis, popliteal tracking during knee flexion is modified compared to the preoperative situation. The location of the popliteus in three cadaver knees was measured using computed tomography, before and after implantation of plastic TKA replicas, by injecting the tendon with radiopaque liquid. The pre- and post-operative positions of the popliteus were compared from full extension to deep flexion using normosized, oversized, and undersized implants (one size increments). At the tibia, TKA caused the popliteus to translate posteriorly, mostly in full extension: 4.1 +/- 2 mm for normosized implants, and 15.8 +/- 3 mm with oversized implants, but no translations were observed when using undersized implants. At the femur, TKA caused the popliteus to translate laterally at deeper flexion angles, peaking between 80A degrees and 120A degrees: 2 +/- 0.4 mm for normosized implants and 2.6 +/- 0.5 mm with oversized implants. Three-dimensional analysis revealed prosthetic overhang at the posterosuperior corner of normosized and oversized femoral components (respectively, up to 2.9 mm and 6.6 mm). A well-sized tibial component modifies popliteal tracking, while an undersized tibial component maintains more physiologic patterns. Oversizing shifts the popliteus considerably throughout the full arc of motion. This study suggests that both femoro- and tibio-popliteus impingements could play a role in residual pain and stiffness after TKA

Does location of patellofemoral chondral lesion influence outcome after Oxford medial compartmental knee arthroplasty?

AIMS: Medial unicompartmental knee arthroplasty (UKA) is associated with successful outcomes in carefully selected patient cohorts. We hypothesised that severity and location of patellofemoral cartilage lesions significantly influences functional outcome after Oxford medial compartmental knee arthroplasty. PATIENTS AND METHODS: We reviewed 100 consecutive UKAs at minimum eight-year follow-up (96 to 132). A single surgeon performed all procedures. Patients were selected based on clinical and plain radiographic assessment. All patients had end-stage medial compartment osteoarthritis (OA) with sparing of the lateral compartment and intact anterior cruciate ligaments. None of the patients had end-stage patellofemoral OA, but patients with anterior knee pain or partial thickness chondral loss were not excluded. There were 57 male and 43 female patients. The mean age at surgery was 69 years (41 to 82). At surgery the joint was carefully inspected for patellofemoral chondral loss and this was documented based on severity of cartilage loss (0 to 4 Outerbridge grading) and topographic location (medial, lateral, central, and superior or inferior). Functional scores collected included Oxford Knee Score (OKS), patient satisfaction scale and University College Hospital (UCH) knee score. Intraclass correlation was used to compare chondral damage to outcomes. RESULTS: All patients documented significant improvement in pain and improved functional scores at mid-term follow-up. There were four revisions (mean 2.9 years, 2 to 4; standard deviation (sd) 0.9) in this cohort, three for tibial loosening and one for femoral loosening. There was one infection that was treated with debridement and insert exchange. The mean OKS improved from 23.2 (sd 7.1) to 39.1 (sd 6.9); p < 0.001. The cohort with central and lateral grade 3 patellofemoral OA documented lower mean satisfaction with pain (90, sd 11.8) and function (87.5, sd 10.3) on the patient satisfaction scale. On the UCH scale, patients reported significantly decreased mean overall scores (7.3, sd 1.2 vs 9, sd 2.3) as well as stair climb task (3.5, sd 0.3 vs 5, sd 0.1) when cartilage lesions were located centrally or laterally on the PFJ. Patients with medial chondral PFJ lesions behave similar to patients with no chondral lesions. CONCLUSION: Topographical location and severity of cartilage damage of the patella can significantly influence function after successful Oxford medial UKA. Surgeons should factor this in when making their operative decision, and undertake to counsel patients appropriately. Cite this article: Bone Joint J 2016;98-B(10 Suppl B):11-15

A novel handheld robotic-assisted system for unicompartmental knee arthroplasty: surgical technique and early survivorship.

Technology, including robotics, has been developed for use in unicompartmental knee arthroplasty (UKA) to improve accuracy and precision of bone preparation, implant positioning, and soft tissue balance. The NAVIO™ System (Smith and Nephew, Pittsburgh, PA, United States) is a handheld robotic system that assists surgeons in planning implant positioning based on an individual patient\u27s anatomy and then preparing the bone surface to accurately achieve the plan. The surgical technique is presented herein. In addition, initial results are presented for 128 patients (mean age 64.7 years; 57.8% male) undergoing UKA with NAVIO. After a mean of follow-up period of 2.3 years, overall survivorship of the knee implant was 99.2% (95% confidence interval 94.6-99.9%). There was one revision encountered during the study, which was due to persistent soft tissue pain, without evidence of loosening, subsidence, malposition or infection. These initial results suggest a greater survivorship than achieved in the same follow-up time intervals in national registries and cohort studies, though further follow-up is needed to confirm whether this difference is maintained at longer durations

The wear of fixed and mobile bearing unicompartmental knee replacements

Unicompartmental knee replacements (UKR) are an option for surgical intervention for the treatment of single-compartment osteoarthritis. The aim of this study was to compare the wear of a low-conformity fixed-bearing UKR with a conforming mobile bearing UKR under two kinematic conditions, to investigate the effect of implant design and kinematics on wear performance in a physiological knee wear simulator. Under both sets of kinematic conditions, the relatively low-conforming fixed UKR showed lower wear, compared with the more conforming anterior-posterior sliding mobile bearing. However, it should be noted that differences in materials between the two designs also contribute to the relative wear performance of the bearings. The combined wear of the medial and lateral bearings of the fixed-bearing UKR as a ‘total knee’ were significantly reduced compared with a fixed-bearing total knee replacement studied under the same kinematic condition

Comparison of Open Wedge High Tibial Osteotomy versus Unicondylar Knee Replacement for Medial Knee Osteoarthritis

Introduction: Medial knee osteoarthritis is a source of debilitating pain. Varus malalignment is associated with a 4-fold increase in unicompartmental osteoarthritis. Current non-surgical treatments include patient education, weight loss, analgesics. Two contemporary surgical treatment options for medial knee osteoarthritis are available and each procedure has its merits. These are based on different principles: high tibial osteotomy (OW- HTO) where correction of knee angular deformity with slight valgus overcorrection is the goal and unicondylar knee replacement (UKA) surgery’s aim in replacing damaged articular surface. Aim: To review clinical outcomes of two matched populations between open wedge high tibial osteotomy (OW-HTO) and unicondylar knee (UKA). Material and Methods: This was a prospective study of two matched populations at two different centres, employing different techniques for managing medial knee compartment osteoarthritis. The OW-HTO centre had recruited 19 patients over February 2012 to December 2013. The TomoFix® knee osteotomy. The unicondylar knee replacement (UKA) centre had 22 patients over June 2012 to August 2013 and used the Oxford™ partial knee system in these operations. Conclusion: In conclusion, this study shows that open wedge high tibial osteotomy and unicondylar knee replacements have no significant differences in oxford scores at 6 weeks and 6 months

Valutazione cinematica intraoperatoria con utilizzo del navigatore e postoperatoria con rsa dinamica nelle protesi totali di ginocchio

Restoring a correct implant kinematics and providing a good ligament balance and patellar tracking is mandatory to improve clinical and functional outcome after a Total Knee Replacement. Surgical navigation systems are a reliable and accurate tool to help the surgeon in achieving these goals. The aim of the present study was to use navigation system with an intra-operative surgical protocol to evaluate and determine an optimal implant kinematics during a Total Knee Replacement

In vivo kinematics of medial unicompartmental osteoarthritic knees during activities of daily living

Few studies exist describing unicompartmental osteoarthritic knee kinematics. Moreover, the role of the anterior cruciate ligament (ACL) in the determination of knee kinematics has not been fully described. The objective of the current study was to analyze the in vivo kinematics of knees with medial osteoarthritis (OA) and intact ACL during closed and open chained motion. Eight patients scheduled for UKA diagnosed with primary medial OA underwent knee CT-scans and video-fluoroscopy. Fluoroscopic analysis included stair climbing, chair rising and leg extension. Three-dimensional bone positions were obtained from each image by iterative procedures using a CAD-model-based shape-matching technique. Patterns of axial rotation and anterior-posterior (AP) motion of the medial and lateral femoral condyle were obtained with specific software. The femur reported an overall external rotation relative to the tibia from extension to flexion in all tasks. Average AP translation of the medial femoral condyle were smaller in open-chained tasks than in weight-bearing conditions. Average AP motion of the lateral femoral condyle reported an overall posterior translation with knee flexion. The absent natural "screw-home" mechanism and the lack of medial condyle posterior translation was explained by bone-cartilage defects and meniscal degeneration. Relevant findings were the kinematic pattern differences between weight-bearing and open chained activities, suggesting that in biphasic muscle contraction and unloaded conditions, the function of the cruciate ligaments was not physiological. The kinematics of knees with medial OA and intact ACL differed from healthy knees.Few studies exist describing unicompartmental osteoarthritic knee kinematics. Moreover, the role of the anterior cruciate ligament (ACL) in the determination of knee kinematics has not been fully described. The objective of the current study was to analyze the in vivo kinematics of knees with medial osteoarthritis (OA) and intact ACL during closed and open chained motion. Eight patients scheduled for UKA diagnosed with primary medial OA underwent knee CT-scans and video-fluoroscopy. Fluoroscopic analysis included stair climbing, chair rising and leg extension. Three-dimensional bone positions were obtained from each image by iterative procedures using a CAD-model-based shape-matching technique. Patterns of axial rotation and anterior-posterior (AP) motion of the medial and lateral femoral condyle were obtained with specific software.The femur reported an overall external rotation relative to the tibia from extension to flexion in all tasks. Average AP translation of the medial femoral condyle were smaller in open-chained tasks than in weight-bearing conditions. Average AP motion of the lateral femoral condyle reported an overall posterior translation with knee flexion.The absent natural "screw-home" mechanism and the lack of medial condyle posterior translation was explained by bone-cartilage defects and meniscal degeneration. Relevant findings were the kinematic pattern differences between weight-bearing and open chained activities, suggesting that in biphasic muscle contraction and unloaded conditions, the function of the cruciate ligaments was not physiological. The kinematics of knees with medial OA and intact ACL differed from healthy knees

Spontaneous osteonecrosis of the knee. Treatment and evolution

We performed a retrospective study on 21 patients affected by unilateral spontaneous osteonecrosis of the femoral condyle. Fifteen were women and 6 men. Their average age was 66.9 years. In ten cases the onset of pain was sudden, with a clear previous history of trauma in two of them. Gait pain, effusion, and joint locking were the most frequent clinical symptoms. At the time of diagnosis, 7 patients presented with grade I necrosis, 8 grade II, 1 grade III, and 5 grade IV, following Koshino's classification [11]. The average percentage of osteonecrosis was 36.8%. Six patients underwent conservative treatment with physical exercises and nonsteroidal anti-inflammatory drugs. We performed arthroscopy alone in 4 patients, arthroscopy and drilling in 8, valgus high tibial osteotomy in 2, and total knee arthroplasty in 1. The overall results after an average follow-up 41 months were excellent and good in 76.2% of the cases, fair in 14.3%, and poor in 9.5%. An associated medial meniscus tear was found in half of the patients who underwent surgery. In patients diagnosed with grade III and IV osteonecrosis, no increase in the percentage of necrosis was observed