Level II, Diagnostic study.

No abstract

Anatomic reconstruction of the MPFL with either a gracilis or a fascia lata graft showed comparable patellofemoral pressure distributions which were closely restored compared to the native knee. Therefore, the fascia lata has shown to be a viable alternative to the gracilis tendon for reconstruction of the MPFL. However, anatomic reconstruction of the MPFL may lead to persistently altered patellofemoral contact pressure during knee flexion compared to the native knee independent of the tested graft.

The medial patellofemoral ligament (MPFL) ensures stability of the patella against lateral forces. In cases of recurrent lateral patellar luxation, surgical reconstruction of the MPFL has an important role in treating lateral patellar instability. Several biomechanical studies have presented valuable pieces of information about various techniques for re-creating this medial patellofemoral complex mainly using the gracilis tendon as an autograft. However, with the increasing number of MPFL reconstructions, there are also an increasing number of patients requiring revision MPFL reconstruction. Therefore alternative graft options may become more relevant. Furthermore, the gracilis tendon as a tubular graft may not be able to fully restore patellofemoral kinematics compared with the native MPFL. This article introduces a surgical technique using the fascia lata as an alternative graft option for the anatomic reconstruction of the MPFL.

No abstract

BackgroundMany different fixation devices are used to maintain the correction angle after medial open wedge high tibial osteotomy (MOWHTO). Each device must provide at least sufficient mechanical stability to avoid loss of correction and unwanted fracture of the contralateral cortex until the bone heals. In the present study, the mechanical stability of following different implants was compared: the TomoFix small stature (sm), the TomoFix standard (std), the Contour Lock, the iBalance and the second generation PEEKPower. Simplified loading, usually consisting of a vertical load applied to the tibia plateau, is used for experimental testing of fixation devices and also in numerical studies. Therefore, this study additionally compared this simplified experimental loading with a more realistic loading that includes the muscle forces.MethodTwo types of finite element models, according to the considered loading, were created. The first type numerically simulated the static tests of MOWHTO implants performed in a previous experimental biomechanical study, by applying a vertical compressive load perpendicularly to the plateau of the osteotomized tibia. The second type included muscle forces in finite element models of the lower limb with osteotomized tibiae and simulated the stance phase of normal gait. Section forces in the models were determined and compared. Stresses in the implants and contralateral cortex, and micromovements of the osteotomy wedge, were calculated.ResultsFor both loading types, the stresses in the implants were lower than the threshold values defined by the material strength. The stresses in the lateral cortex were smaller than the ultimate tensile strength of the cortical bone. The implants iBalance and Contour Lock allowed the smallest micromovements of the wedge, while the PEEKPower allowed the highest. There was a correlation between the micromovements of the wedge, obtained for the simplified loading of the tibia, and the more realistic loading of the lower limb at 15% of the gait cycle (Pearson’s value r = 0.982).ConclusionsAn axial compressive load applied perpendicularly to the tibia plateau, with a magnitude equal to the first peak value of the knee joint contact forces, corresponds quite well to a realistic loading of the tibia during the stance phase of normal gait (at 15% of the gait cycle and a knee flexion of about 22 degrees). However, this magnitude of the knee joint contact forces overloads the tibia compared to more realistic calculations, where the muscle forces are considered. The iBalance and Contour Lock implants provide higher rigidity to the bone-implant constructs compared to the TomoFix and the PEEKPower plates.

Purpose To evaluate the optimal graft tension angles in a medial patellofemoral ligament (MPFL) reconstruction with selective bundle tensioning in order to restore patellofemoral contact pressure distributions closest to the native state. Methods Twelve human cadaveric knee specimens were mounted with the femur on a custom‐made fixation device allowing free range of motion in the knee joint for testing. Using a sensitive pressure film (Tekscan) patellofemoral contact pressure was measured in 15° intervals during a dynamic flexion movement from 0°–90° in the native state, in cut MPFL and after MPFL‐reconstruction with a gracilis tendon. The graft was separated in two bundles and was fixed independently on the patella using two knotless anchors. Two groups were made with either the proximal or distal bundle fixed at the femur at a knee flexion angle of 30° and the corresponding other bundle subsequently fixed at the femur at 15°, 45°, 60°, 75° and 90° of knee flexion using extra‐cortical fixation and controlled tension of 2N in both groups. The sequence of the flexion angles at the graft fixation was alternated. Pressure measurements were repeated after every fixation of the graft. Results Cutting the MPFL resulted in significantly reduced patellofemoral contact pressure at all flexion angles. After MPFL reconstruction the patellofemoral contact pressure remained significantly reduced during dynamic knee flexion in all tested double‐bundle combinations (p < 0.05) except for fixation of the proximal bundle in 30° and the distal bundle in 75°. Selective evaluation of lateral patellofemoral contact pressure, however, showed significant reduction in all tested double‐bundle combinations (p < 0.05) from 15° to 90°. Evaluation of isolated medial patellofemoral pressure changes showed no significant difference in all tested combinations compared to the intact knee. Furthermore, evaluation of the isolated proximal and distal patellofemoral contact pressure also revealed a significantly reduced contact pressure in all tested double‐bundle combinations (p < 0.05) except for fixation of the proximal bundle in 30° and the distal bundle in 75°. Conclusion According to this study, selective bundle tensioning in anatomic MPFL‐reconstruction should be considered as an easy and more anatomic alternative to current popular techniques to restore patella kinematics and give clear recommendation about knee flexion angle and tension during fixation. Although tensioning two bundles separately may further improve clinical results. If performed, fixation of the graft is recommended under low tension (2N) with the proximal bundle at 30° and the distal bundle at 75° of knee flexion.

Chronic patellar tendinosis (jumper's knee) is a common problem among athletes. Conservative treatment is successful in most of the cases including, among others, the use of nonsteroidal anti-inflammatory drugs, local cryotherapy, eccentric muscle training, limitation of sports activity, and local infiltration. In approximately 10% of conservatively treated patients, conservative treatment fails and surgery is required. Different open and arthroscopic surgical techniques have been described in the literature. The presented all-arthroscopic surgical technique for the treatment of chronic patellar tendinosis includes debridement of soft tissue at the lower patellar pole and resection of the bony lower patellar pole. It leads to excellent clinical results comparable to described open treatment and provides the benefits of a minimally invasive and safe procedure with a faster recovery and return to sporting activities after surgery. An additional bony resection in case of a prominent lower patellar pole does not lead to a significant extension of the operation time and may avoid a relapse or treatment failure in selective cases. Therefore, arthroscopic treatment such as the presented technique may be the preferred method for surgical treatment of chronic patellar tendinosis.