Osteotomies are performed in patients with lower limb malalignment, usually associated with osteoarthritis of the knee or instability. The surgery realigns the mechanical axis of the leg by either an opening or closing wedge procedure with the goal of decreasing symptoms, improving function, and delaying the progression of osteoarthritis.

The 103 patients that had undergone osteotomy surgery were studied prospectively, and data was analysed one year post surgery. We examined subjective outcomes, patient history and surgical variables using backwards stepwise multiple regression models to determine whether there were any associations between these.

Subjective outcomes from a total of 103 osteotomy patients at one year post surgery were compared to patient history and surgical variables. All categories of KOOS and WOMAC scores were improved after surgery.

The multivariate models showed that variables significantly influencing the outcomes were pre-operative flexion, pre-operative weight, the size of the HTO plate used and tourniquet time.

Greater pre-operative flexion; lower weight; larger plate used, indicating larger corrections; and lower tourniquet times were shown to result in improved scores. Not all variables influenced all categories of the scores. While flexion and pre-operative weight influenced across the categories of both scores, plate size influenced KOOS pain and symptoms and tourniquet time influenced KOOS sport and quality of life.

Knee flexion and body weight were the most influential variables when considering KOOS and WOMAC outcome scores as a measure of success. The size of the correction may have influenced the pain and symptom scores because patients with greater malalignment may have initially had worse symptoms and their perception of their current function and pain is affected by their previous levels of pain and function. Osteotomy results in improved function and pain scores and our results indicate that there are several variables which significantly influence patient outcomes and may be of greater importance than other variables.

Anterior Cruciate Ligament (ACL) reconstruction is a well established procedure for restoration of stability following ACL rupture. Several methods exist for fixation of soft tissue grafts on the tibia, without general agreement about the optimal method. This study compared two different methods of tibial fixation using hamstring grafts in ACL reconstruction.

113 consecutive patients were randomized into two groups at the time of surgery. In group one, fixation was with a metal interference screw (RCI) and staples and in group two, with a polyethylene screw and sheath (Intrafix). Evaluation of outcomes was conducted using KT-1000 arthrometer, Lysholm, IKDC subjective and Mohtadi scores.

7 reinjuries occurred within the time frame of the study, mostly related to sporting injuries, with 5 in group 2. 81% of remaining participants were successfully followed at 2 years post surgery. No significant difference in mean KT-1000 side-to-side measurements was found between groups at an average follow-up of 30 months (1.5 ± 1.9mm and 1.8 ± 1.9mm, respectively; p > 0.05). The mean Lysholm score for group one was 65.2 ± 15.5 preoperatively and 90.8 ± 9.5 postoperatively; for group two these scores were 62.0 ± 20.7 preoperatively and 88.8 ± 14.3 postoperatively. This improvement in scores after surgery was similar for both groups and was not significantly different between groups (p > 0.05). Both the IKDC subjective and Mohtadi scores showed significant (p < 0.05) improvements postoperatively compared with pre-operatively but no significant difference between fixation groups.

There were no significant differences between the two groups for any outcome value, with both methods of graft fixation producing good results. The newer Intra-fix device had a higher reinjury rate but this was not significantly different from the screw and staple fixation, and on all other outcome measures the Intrafix device was equivalent to an interference screw and staples for tibial-sided graft fixation in ACL reconstruction.

Multi-ligament knee injuries require complex surgery. Hinged external fixators propose to control the tibio-femoral relationship, protect reconstructions and allow early mobilisation. However, a uniaxial hinge may be too simplistic for such a complex joint. We investigated the influence of an external fixation device on ligament strains and joint contact forces.

Six fresh frozen cadaveric lower limbs (41–56 years old) were obtained. Displacement transducers (Microstrain, USA) were attached to mid-substance lateral (LCL) and medial collateral (MCL) ligaments, and the anterior and posterior cruciate (PCL) ligaments through minimal soft tissue incisions. Joint pressures were measured by transducers (Tekscan) introduced in the medial and lateral compartments through small sub-meniscal arthrotomies. Flouroscopic imaging was used to construct the hinged fixator centred over the epicondylar axis. Ligament tensile strains and joint contact forces were determined through a passive arc of 20 to 110 degrees of flexion and extension, with and without the external fixator (ExFix^™, EBI Biomet Australia).

The application of the external fixation device resulted in minimal change in the mean peak percentage strain of the PCL, MCL and ACL ligaments, while the LCL peak percentage strain decreased. Generally the peak percentage strain for each ligament occurred at or near the same flexion angle in both the un-instrumented and instrumented case within each limb, but the peak percentage strain flexion angles varied significantly across limbs. Peak joint contact forces increased significantly (p < 0.05) in the lateral compartment after attachment of the external fixation device. There was no difference seen in the medial compartment joint contact forces.

This study shows that a uniaxial hinged external fixator can be used in a multi-ligament reconstructed knee to maintain joint congruence and allow early postoperative rang of motion without compromising the results of reconstructions or repairs.

Understanding of mechanical factors influencing knee joint loading is crucial for insight into OA progression and development of prevention and treatment strategies. High tibial osteotomy (HTO) changes knee alignment. Forces and moments should also be altered and reduce loading on one compartment.

15 subjects undergoing high tibial osteotomy were enrolled in the study. Markers were placed on prominent anatomical landmarks to indicate 12 body segments. Three dimensional positions of each marker were calculated using fourteen cameras (Eagle 8 mm, Motion Analysis Corp.) recording at 100Hz and a motion analysis system (EvaRT4.6, Motion Analysis Corp.). Three-dimensional external moments and inter-segmental joint forces were calculated using inverse dynamics in the Kintrak^™ software. Kinematic and kinetic data from