Aims. The aim of this study was to determine the association between knee alignment and the vertical orientation of the femoral neck in relation to the floor. This could be clinically important because changes of femoral neck orientation might alter chondral joint contact zones and joint reaction forces, potentially inducing problems like pain in pre-existing chondral degeneration. Further, the femoral neck orientation influences the ischiofemoral space and a small ischiofemoral distance can lead to impingement. We hypothesized that a valgus knee alignment is associated with a more vertical orientation of the femoral neck in standing position, compared to a varus knee. We further hypothesized that realignment surgery around the knee alters the vertical orientation of the femoral neck. Methods. Long-leg standing radiographs of patients undergoing realignment surgery around the knee were used. The hip-knee-ankle angle (HKA) and the vertical orientation of the femoral neck in relation to the floor were measured, prior to surgery and after osteotomy-site-union. Linear regression was performed to determine the influence of knee alignment on the vertical orientation of the femoral neck. Results. The cohort included 147 patients who underwent knee realignment-surgery. The mean age was 51.5 years (SD 11). Overall, 106 patients underwent a valgisation-osteotomy, while 41 underwent varisation osteotomy. There was a significant association between the orientation of the knee and the coronal neck-orientation. In the varus group, the median orientation of the femoral neck was 46.5° (interquartile range (IQR) 49.7° to 50.0°), while in the valgus group, the orientation was 52.0° (IQR 46.5° to 56.7°; p < 0.001). Linear regression analysis revealed that HKA demonstrated a direct influence on the coronal neck-orientation (β = 0.5 (95% confidence interval (CI) 0.2 to 0.7); p = 0.002). Linear regression also showed that realignment surgery was associated with a significant influence on the change in the coronal femoral neck orientation (β = 5.6 (95% CI 1.5 to 9.8); p = 0.008). Conclusion. Varus or valgus knee alignment is associated with either a more horizontal or a more vertical femoral neck orientation in standing position, respectively. Subsequently, osteotomies around the knee alter the vertical orientation of the femoral neck. These aspects are of importance when planning osteotomies around the knee in order to appreciate the effects on the adjacent hip joint. The concept may be of even more relevance in dysplastic hips. Cite this article: Bone Jt Open 2021;2(12):1057–1061

Total hip arthroplasty (THA) for congenital hip dysplasia (CDH) presents a challenge. In high-grade CDH, key surgical targets include cup placement in the anatomical position and leg length equality. Lengthening of more than 4 cm is associated with sciatic nerve injury, therefore shortening osteotomies are necessary. We present our experience of different shortening osteotomies including advantages and disadvantages of each technique. 89 hips, in 61 pts (28 bilateral cases), for high CDH were performed by a single surgeon from 1997 to 2022. 67 patients were female and 22 were male. Age ranged from 38 to 68 yrs. In all patients 5–8cm of leg length discrepancy (LLD) was present, requiring shortening femoral osteotomy. 12 patients underwent sequential proximal femoral resection with trochanteric osteotomy, 46 subtrochanteric, 6 midshaft, and 25 distal femoral osteotomies with simultaneous valgus correction were performed. All acetabular prostheses were placed in the true anatomical position. We used uncemented high porosity cups. Patients were followed up for a minimum of 12 months. All osteotomies healed uneventfully except 3 non-unions of the greater trochanter in the proximal femur resection group. No femoral shaft fractures in proximally based osteotomies. No significant LLD compared to the unaffected or reconstructed side. 2 patients suffered 3 and 5 degrees malrotation of the femur in the oblique sub-trochanteric group. 3 patients suffered transient sciatic nerve palsies. Shortening femoral osteotomies in the treatment of DDH are necessary to avoid injury to the sciatic nerve. In our series, we found transverse subtrochanteric osteotomies to be the most technically efficient, versatile and predictable in their clinical outcome, due to the ability to correct rotation and preserve the metaphyseal bone integrity, allowing for better initial stem stability. Distal femoral osteotomies allowed for controllable correction of valgus knee deformity

The coronal plane lower limb alignment plays an important role in the occurrence and progression in knee osteoarthritis. There have been reports of the valgus knee in patients with unilateral developmental hip dislocation (UDHD) with the relatively small sample size. Besides, few studies have analyzed the lower limb alignment of the contralateral side. The purpose of our study was to identify the coronal plane alignment of both the ipsilateral and the contralateral lower limb in patients with UDHD and find out the difference between patients with Hartofilakidis type II and III. The radiographic data of all UDHD patients who met the inclusion criteria from March 2011 to February 2017 were retrospectively reviewed, including the hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), anatomical lateral distal femoral angle (aLDFA), mechanical proximal tibial angle (MPTA) and the lateral distal tibial angle (LDTA). Besides, the femoral torsion angle was measured on the images of CT scan. The average HKA was 3.42°(range: −4.3–12.8°) on the affected side, and −2.11°(range: −11.4–5.4°) on the contralateral side (P?0.0001). The valgus lower limb alignment on ipsilateral side was most frequently seen in both Hartofilakidis type II (20cases, 51.3%) and type III groups (25cases, 67.6%), whereas for the contralateral side, the neutral alignment in type II group (27 cases, 69.2%) and varus alignment in type III group (19 cases, 51.4%) were most commonly observed. Both the mLDFA (P?0.001) and aLDFA (P?0.001) of ipsilateral side were significantly smaller than those of contralateral side. The average femoral torsion angle was 37.9°(range: 10.4–64.4°) on the affected side, and 27.1°(range: 9.7–45.5°) on the contralateral side (P?0.001). In conclusion, UDHD patients may present with lower limb malalignment on both sides. The valgus lower limb alignment is the most common deformity on ipsilateral side, which is caused by increased femoral torsion angle as well as the decreased aLDFA. The patients with Hartofilakidis type III UDHD may be more prone to present varus alignment deformity than those with Hartofilakidis type II on the contralateral side. The lower limb malalignment and deformity of ipsilateral distal femur should be considered during any surgery involving hip, knee or femur