Femoral Neck Stress Fractures: An Updated Review.

Femoral neck stress fractures represent a relatively rare spectrum of injuries that most commonly affect military recruits and endurance athletes. If unrecognized and if proper treatment is not initiated, this condition carries potentially devastating consequences. Patients will typically present with an insidious onset, atraumatic hip, and groin pain that is relieved with rest. The condition may be initially misdiagnosed because radiographs are often normal. Magnetic resonance imaging has demonstrated superior specificity, sensitivity, and accuracy compared with other diagnostic modalities in identifying and classifying stress fractures of the femoral neck. Treatment algorithms are based on the MRI fracture morphology and presence of an intra-articular effusion. Nonsurgical management consists of a period of non-weight-bearing followed by gradual return to activity. Surgical management consists of prophylactic fracture fixation with cannulated screws to prevent fracture progression. If left untreated, patients may progress to a complete displaced femoral neck fracture, which can be associated with complications that include nonunion, osteonecrosis of the femoral head, and long-term disability. These poor outcomes emphasize the importance of early diagnosis and treatment of incomplete femoral neck stress fractures.

Non-displaced Femoral Neck Stress Fractures in Young Adults: 7-Year Outcomes of Prophylactic Fixation Versus Nonoperative Treatment.

Retrospectively compare outcomes of prophylactic fixation to nonoperative treatment of incomplete or non-displaced femoral neck stress fractures (FNSF) in young adults. Outcomes of 82 patients (mean age 21.7 years) who were diagnosed with incomplete or non-displaced FNSFs from 2002 to 2015 were compared. Forty-one underwent prophylactic fixation; the remaining were treated without surgery. Fracture characteristics and complications were recorded. Pain scores, modified Harris Hip Scores (mHHS), and Hip Outcome Scores (HOS) were obtained and compared. The average fracture line in the operative group was 67% of the femoral neck width versus 18% in the nonoperative group (p < 0.001). There was no difference in outcome scores between the two groups. Prophylactic fixation of high-risk non-displaced FNSFs resulted in similar outcome scores to non-operative management of lower-risk variants at an average of 7.3 years follow up. No patient in either group progressed to a displaced femoral neck stress fracture. (Journal of Surgical Orthopaedic Advances 29(3):173-176, 2020).

Outcomes Following the Urgent Surgical Management of Displaced Femoral Neck Stress Fractures.

OBJECTIVES: To review the clinical course, complication rates, and mid-term functional outcomes associated with the treatment of displaced femoral neck stress fractures (FNSFs). DESIGN: Retrospective Case Series. SETTING: Military Tertiary Referral Center. PATIENTS: Twenty-one operatively treated displaced FNSFs between 2002 and 2015. INTERVENTION: Urgent reduction and fixation was performed. If nonunion developed, an intertrochanteric osteotomy was performed. MAIN OUTCOME MEASUREMENTS: Nonunion, osteonecrosis (ON) of the femoral head, conversion to arthroplasty, modified Harris Hip Score, pain score, and Hip Outcome Score (HOS). RESULTS: Two (9.1%) patients developed nonunion. Both united after revision with intertrochanteric osteotomy. ON developed in one patient (4.8%) who was converted to arthroplasty. Average pain score at final follow-up was 2.0 (range 0-5). Average Modified Harris Hip Score was 84 (range 54-100). Average HOS Activities of Daily Living subscale was 80.9 (range 45.6-100). Average HOS Sport subscale was 69.8 (range 27.8-100). Larger displacement on injury films correlated with lower Modified Harris Hip Scores (P = 0.048) and lower HOS Sports Subscale Single Assessment Numeric Evaluation (P = 0.023). The need for an open reduction trended toward being a risk factor for nonunion (P = 0.081). CONCLUSIONS: This study represents the largest series of patients undergoing urgent surgery for displaced FNSFs. Nonunion and ON is found at a similar rate to what is reported in the young traumatic literature. Pain and outcome scores compare favorably to other hip pathology in young adults. Initial injury severity is variably correlated to final outcome scores. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Does Screw Location Affect the Risk of Subtrochanteric Femur Fracture After Femoral Neck Fixation? A Biomechanical Study.

BACKGROUND: Case reports suggest that there is an increased risk of subtrochanteric femur fracture after femoral neck fixation with cannulated screws when the distal-most screw is placed distal to the lesser trochanter. However, to our knowledge, there are no biomechanical data supporting this observation. QUESTIONS/PURPOSES: (1) Is there an increased risk of subtrochanteric femur fracture after femoral neck fixation with cannulated screws in normal density and osteoporotic Sawbones when the distal-most screw is started distal to the lesser trochanter? (2) Does the screw starting point position after femoral neck fixation with cannulated screws affect load to failure when normal density and osteoporotic Sawbones are loaded through their mechanical axis? METHODS: Normal density and osteoporotic Sawbones femora were instrumented with three cannulated screws in a triangular apex distal configuration with the distal-most screw starting either proximal to, at, or distal to the level of the lesser trochanter. Specimens were loaded along the mechanical axis to failure. The fracture location and ultimate load to failure were compared between groups. RESULTS: The screw start point distal to the lesser trochanter resulted in a greater proportion of subtrochanteric femur fractures compared with screw start points at or proximal to the lesser trochanter in the subset of osteoporotic specimens (three of 10 specimens versus 0 of 20 specimens; p = 0.030). No subtrochanteric femur fractures were observed in the normal density specimens. Load to failure was lower when the distal-most screw was started distal to the lesser trochanter than when it was started at or proximal to the lesser trochanter (normal density subset 13,502 ± 1980 N versus 14,675 ±1528 N; osteoporotic subset 8946 ± 1509 N versus 10,026 ± 1256 N; linear regression coefficient 1127 N [95% CI 298 to 1956 N]; adjusted r = 0.71; p = 0.009). CONCLUSIONS: A screw start point distal to the lesser trochanter was associated with subtrochanteric femur fractures in the osteoporotic subset. Additionally, there was decreased load to failure when the distal-most screw was started distal to the lesser trochanter. CLINICAL RELEVANCE: These data suggest that avoiding a screw start point distal to the level of the lesser trochanter in femoral neck fracture fixation may decrease the risk of catastrophic subtrochanteric femur fractures, especially in patients with osteoporosis. However, it should be noted that a more overall varus screw alignment could theoretically compromise the ability to achieve compression across the fracture, with attendant implications with regard to fracture union in the acute setting.