Treatment of both simple and complex patella fractures is a challenging clinical problem. The aim of this study was to investigate the biomechanical performance of recently developed lateral rim variable angle locking plates versus tension band wiring used for fixation of simple and complex patella fractures.

Twelve pairs of human anatomical knees were used to simulate either two-part transverse simple AO/OTA 34C1 or five-part complex AO/OTA 34C3 patella fractures by means of osteotomies, with each fracture model created in six pairs. The complex fracture pattern was characterized by a medial and a lateral proximal fragment, together with an inferomedial, an inferolateral, and an inferior fragment mimicking comminution around the distal patellar pole. The specimens with simple fractures were pairwise assigned for fixation with either tension band wiring through two parallel cannulated screws, or a lateral rim variable angle locking plate. The knees with complex fractures were pairwise treated with either tension band wiring through two parallel cannulated screws plus circumferential cerclage wiring, or a lateral rim variable angle locking plate.

Each specimen was tested over 5000 cycles by pulling on the quadriceps tendon, simulating active knee extension and passive knee flexion within the range of 90° flexion to full knee extension. Interfragmentary movements were captured via motion tracking.

For both fracture types, the longitudinal and shear articular displacements measured between the proximal and distal fragments at the central patella aspect between 1000 and 5000 cycles, together with the relative rotations of these fragments around the mediolateral axis were all significantly smaller following the lateral rim variable angle locked plating compared with tension band wiring, p<0.01.

Lateral rim locked plating of both simple and complex patella fractures provides superior construct stability versus tension band wiring under dynamic loading.

The purposes of this study were to determine the effect of severity, wait times and patient perspective on outcomes and to create an eivdence-based prioritization tool.

Patients who received a primary hip or knee replacement were followed forward from decision date for surgery to one-year follow-up (N = 4437) and outcomes assessed according to baseline severity. At decision date for surgery, patient baseline severity was captured using the WOMAC disability questionnaire. Twelve to eighteen months after surgery, a questionnaire (WOMAC, satisfaction) was sent to patients to compare pre- and post-operative data.

The chance of a good outcome from TJR surgery gets worse as wait times get longer. Baseline severity affects outcome more than wait times. Patients with a baseline WOMAC less then 30/100 should have surgery within three months (20% patients) If surgery cannot be done within three months, then three priority levels are recommended: Priority I – One month maximum: catastrophic hip or knee joint conditions – complications that are an immediate threat to independence. Priority II – three months maximum: extreme pain and disability because of hip or knee joint condition that will be a threat to role and independence within three months (baseline WOMAC less than or equal to 30/100). Priority III – six months maximum: severe pain or disability because of hip or knee joint condition, but role and independence not threatened (baseline WOMAC over 30/100).

The priority levels and wait time thresholds recommended in this study are the result of an analysis of pre-operative severity scores, the length of the wait and post-operative outcomes and are consistent with data from other sources.