The constitutional knee anatomy in the coronal plane includes the distal femoral joint line obliquity (DFJLO) which in most patients is in slight valgus positioning. Despite this native anatomy, the mechanical positioning of the femoral component during primary total knee arthroplasty (TKA) often ignores the native DFJLO opting to place the femur in a set degree of valgus that varies upon the practitioner's practice and experience. Unfortunately, this technique is likely to generate high rate of distal lateral femoral overstuffing. This anatomical mismatch might be a cause of anterior knee pain and therefore partly explain the adverse functional outcomes of mechanically aligned (MA) TKA. Our study aims at assessing the relationship between constitutional knee anatomy and clinical outcomes of MA TKA. We hypothesized that a negative relationship would be found between the constitutional frontal knee deformity, the distal femoral joint line obliquity, and functional outcomes of MA TKA with a special emphasize on patellofemoral (PF) specific outcomes. One hundred and thirteen patients underwent MA TKA (posterior-stabilized design) for primary end-stage knee osteoarthritis. They were prospectively followed for one year using the New KSS 2011 and HSS Patella score. Residual anterior knee pain was also assessed. Knee phenotypes using anatomical parameters (such as HKA, HKS, DFJLO and LDFA (Lateral distal femoral angle)) were measured from preoperative and postoperative lower-limb EOS® images (Biospace, Paris, France). We assessed the relationship between the knee anatomical parameters and the functional outcome scores at 1 year postoperatively.Introduction
Methods
The alternative kinematic alignment (KA) technique for total knee arthroplasty (TKA) aims at restoring the native joint line orientation and laxity of the knee. The goal is to generate a more physiological prosthetic knee enabling higher functional performance and satisfaction for the patient. KA TKA have only been reported so far with cruciate retaining and posterior-stabilised designs. Similarly, medial pivot design for TKA has been recently developed to enable more natural knee kinematics and antero-posterior stability. The superiority of KA technique and medial pivot implant design is still controversial when compared to current practice. Our study aims to assess the value of KA TKA when performed with medial pivot implants. We conducted a retrospectively matched case-control study. Clinical data was prospectively collected on patients as part of an ongoing ODEP study. Thirty-three non-selected consecutive KA TKAs performed by the lead author were matched to a control group of 33 measured resection with mechanically aligned (MA) TKAs performed by other consultant surgeons. Patients were matched for sex, age, BMI and pre-operative Oxford Knee Score (OKS). Pre-operative median OKS was 21 points (max 48), mean age was 69, mean BMI 31, and there were 21 female patients in both arms. The medial pivot GMK Sphere implant (Medacta, Switzerland) was used in all cases. OKS and EQ-5D scores were measured pre-operatively and at 1-year post-op. Patient outcome satisfaction scores were assessed at 1-year follow-up using a visual analogic scale (VAS). Pre- and post-operative knee radiographs were analysed using TraumaCad software.Introduction
Methods
