---

Background: Valgus deformity (more than 10° valgus on anatomical measurement) is seen in about 10% of patients undergoing total knee arthroplasty (TKA). Valgus deformity is a challenge for the surgeons both for gap balancing and constraint choice.

---

Background: During a total knee arthroplasty, it is common to make a distal femoral cut based on the femoral mechanical-anatomical angle (FMA), which in most patients is six degrees. However, in patients with a higher FMA, there is not yet a consensus between surgeons regarding the degree of the cutting angle.

---

Background: There is no consensus regarding the effect of the type of deformities (valgus or varus) on the functional outcome of total knee arthroplasty (TKA). We aimed to compare the TKA outcome in varus and valgus patients to find whether different angulations of the knee could affect the functional outcome of the TKA.

---

Femoral neck stress fractures are rare and encompass 5% of all stress fractures among the young people. The bilateral cases are very rare. Coxa vara deformity and morbid obesity are some of the predisposing factors for bilateral stress fractures. The decline of neck-shaft angle will result in an increase and concentration of stress force in femoral neck giving rise to fracture. This report introduced a 35-year-old man with severe coxa vara deformity with an angle of 100 neck-shaft who had a bilateral femoral neck stress fracture and severe obesity [body mass index (BMI) >; 35 kg/m2]. The femoral neck stress fracture was a tension-type occurred due to stress in coxa vara. Based on laboratory findings, his vitamin D deficiency was severe (8.9 ng/mL) but his PTH and phosphorus levels were normal. Regarding vitamin D deficiency and previous femoral deformity, the possibility of osteomalacia in adolescence period was raised. Bilateral valgus sub-trochanteric osteotomy and fixation with a dynamic hip screw (DHS) were performed. After three months, the patient restored his walking ability and weight bearing. Valgus sub-trochanteric osteotomy and fixation with DHS are useful methods in coxa vara deformity concomitant with stress fractures and can modify the neck-shaft angle.

---

Background: Femoral neck fracture nonunion is a frequent and challenging complication, with several surgical options. 
Objectives: The present study reported the outcome of valgus osteotomy for treating femoral neck nonunion in patients aged <65 years.
Methods: This case series research included young patients who underwent valgus osteotomy for treating femoral neck nonunion or device failure of the index surgery. The fixation of the osteotomy site was performed using either a dynamic hip screw or a fixed angle blade. The union of the neck and osteotomy site (subtrochanteric region) was evaluated by monitoring callus formation in the postoperative radiographs. Limb length discrepancy, Pauwels’ angle, and the neck-shaft angle were evaluated before the surgery and at the last follow-up. Postoperative complications were extracted from the explored patients’ profiles. 
Results: Twenty patients with a Mean±SD age of 27.2±10.8 years were examined in this study‎. The Mean±SD follow-up time of the patients was 6.1±3.9 years. The femoral neck was united in 18 patients in a Mean±SD period of 5.1±2.3 months. The Mean±SD limb length discrepancy was measured as 1.3±0.8 cm before and 0.5±0.7 cm after the ‏osteotomy. The Mean±SD Pauwels’ angle was calculated as 65.5±16.9º before and 32.4±16.2º after the osteotomy. The Mean±SD neck-shaft angle was computed to be 121.9±22.8º before and 144.5±17.7º after the osteotomy. Revision surgery was performed for 6 (30%) patients. This measure included device removal in 4 and total hip arthroplasty in 2 patient.
Conclusion: Valgus osteotomy is a safe and efficient technique for managing femoral neck nonunion. Therefore‎, this approach is suggested as a good alternative for total hip arthroplasty, particularly in young and active patients‎.

---