Purpose Increased femoral antetorsion influences patellofemoral joint kinematics. The aim of this study was to retrospectively evaluate the clinical outcome after derotational osteotomies and combined procedures in patients with patellofemoral instability. Methods All patients with derotational osteotomies and combined procedures in patients with patellofemoral instability and increased femoral antetorsion performed between 2007 and 2016 were retrospectively analyzed. Exclusion criteria were open growth plates, posttraumatic deformities, and a follow‐up period less than 12 months. Simple radiography and magnetic resonance imaging to evaluate cartilage lesions, trochlear dysplasia, tubercle distance, and osseous malalignment as frontal axis and torsion were performed on every patient. Patients were evaluated pre‐ and postoperatively using the visual analog scale (VAS) for pain, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, the subjective IKDC evaluation form, the Lysholm score, and the Tegner activity score. Results Out of 222 femoral osteotomies, a total of 42 patients (44 knees) met the inclusion criteria. Mean preoperative femoral antetorsion of 31° (SD ± 9°) and mean valgus malalignment of 1° (SD ± 3°) were observed. An intended derotation of 12° (SD ± 5°) was set overall. The additional procedures included correction of valgus in 50% (n = 22), MPFL reconstruction in 64% (n = 28), patellofemoral arthroplasty in 18% (n = 8), trochleoplasty in 14% (n = 6), tibial tubercle transfer in 14% (n = 6). During the mean follow‐up period of 44 months (SD ± 27, range 12–88), a total of five patients were lost to follow‐up, resulting in a follow‐up rate of 89% (n = 39). A significant pain relief from VAS 4 (SD ± 3) to VAS 2 (SD ± 2) (p = 0.006) as well as improved scores, WOMAC: from 80 (SD ± 14) to 88 (SD ± 16) (p = 0.007), Lysholm: from 46 (SD ± 21) to 71 (SD ± 24) (p < 0.001), IKDC: from 54 (SD ± 13) to 65 (SD ± 17) (p < 0.001), were observed postoperatively. During the follow‐up period, no patellar re‐dislocation was observed. Conclusion Combined derotational osteotomy is a suitable treatment for patellar instability due to torsional malformity, as it leads to a significant reduction of pain, and a significant increase of knee function with good‐to‐ excellent results in the short‐term follow‐up. Level of evidence IV.
Background:Degenerative medial meniscal tears and subsequent partial meniscal resection compromise meniscal function and lead to an overload of the medial compartment. In addition, lower limb alignment plays a key role in load distribution between the medial and lateral knee compartments, and varus alignment is a potential risk factor for medial osteoarthritis.Purpose/Hypothesis:The purpose of this biomechanical study was to investigate the effect of valgus and varus alignment on peak pressure and contact area in knees with concomitant horizontal medial meniscal tears and subsequent leaflet resection. It was hypothesized that varus alignment in combination with meniscal loss leads to the highest peak pressure within the medial compartment.Study Design:Controlled laboratory study.Methods:Six fresh-frozen human cadaveric knees were axially loaded using a 1000-N compressive load in full extension with the mechanical axis rotated to intersect the tibial plateau at 40%, 45%, 50%, 55%, and 60% of its width (TPW) to simulate varus and valgus alignment. Tibiofemoral peak contact pressure and contact area of the medial and lateral compartments were determined using pressure-sensitive foils in each of 4 different meniscal conditions: intact, 15-mm horizontal tear of the posterior horn, inferior leaflet resection, and resection of both leaflets.Results:The effect of alignment on peak pressure (normalized to the neutral axis) within the medial compartment in cases of an intact meniscus was measured as follows: varus shift resulted in a mean increase in peak pressure of 18.5% at 45% of the TPW and 37.4% at 40% of the TPW, whereas valgus shift led to a mean decrease in peak pressure of 8.7% at 55% of the TPW and 23.1% at 60% of the TPW. Peak pressure changes between the intact meniscus and resection within the medial compartment was less in valgus-aligned knees (0.21 MPa at 60% TPW, 0.59 MPa at 50% TPW, and 0.76 MPa at 40% TPW). Contact area was significantly reduced after partial meniscal resection in the neutral axis (intact, 553.5 ± 87.6 mm2; resection of both leaflets, 323.3 ± 84.2 mm2; P < .001). This finding was consistent in any alignment.Conclusion:Both partial medial meniscal resection and varus alignment led to an increase in medial compartment peak pressure. Valgus alignment prevented medial overloading by decreasing contact pressure even after partial meniscal resection. A horizontal meniscal tear did not influence peak pressure and contact area even in varus alignment.Clinical Relevance:As a clinical consequence, partial meniscal resection should be avoided to maintain the original biomechanical behavior, and the mechanical axis should be taken into account if partial meniscectomy is necessary.
LOWDFO is a safe alternative to MCWDFO. Although radiolucency of the osteotomy gap can be evident on radiographs even after 12 months, this does not reflect the clinical finding. The nonunion rate is proven to be low and comparable with the nonunion rates of MCWDFOs as well as open wedge HTOs.
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