Fatigue failure of the cephalomedullary nail: revision options, outcomes and review of the literature

Abstract

Cephalomedullary nail (CMN) failure is a rare entity following hip fracture treatment. However, it poses significant challenges for revision surgery, both mechanically and biologically. Nail failure rates have been reported at < 2%; however, no published studies have reported revision surgery procedures and their respective outcomes. We present a regional experience, with outcomes, of the revision options. We identified 20 fatigued CMNs that underwent four different revision procedures. Mean age was 73 ± 15.24 years, with a 3:1 female preponderance, and a median ASA grade of 3. Post-operative CMN radiographs demonstrated a significant number of fractures were fixed in varus, with reductions in neck-shaft angles post-operatively. A "poor" quality of reduction resulted in significantly earlier nail failure, compared to "adequate" and "good" (p = 0.027). Tip-Apex Distance (TAD) mean was 23.2 ± 8.3 mm, and an adequate TAD with three-point fixation was seen in only 35% of cases. Mean time to failure was 401.0 ± 237.2 days, with mean age at failure of 74.0 ± 14.8 years. Options after failure included revision CMN nail, proximal femoral locking plate (PFLP), long-stem or restoration arthroplasty, or femoral endoprosthesis. Barthel Functional Index scores showed no significant difference at 3 and 12 months post-operatively, nor any difference between treatment groups. Mean 12-month mortality was 30%, akin to a primary hip fracture mortality risk according to NICE guidelines. Mortality rates were lowest in revision nails. Subsequent revision rates were higher in the PFLP group. There is no reported evidence on the best surgical technique for managing the failed CMN, with no clear functional benefit in the options above. Good surgical technique at the time of primary CMN surgery is critical in minimising fatigue failure. After revision, overall mortality rates were equivalent to reported primary hip fracture mortality rates. Further multicentre evaluations are required to assess which technique convey the best functional outcomes without compromising 12-month mortality rates.

Parametric Finite Element Analysis of Intramedullary Nail Fixation of Proximal Femur Fractures

“…Although nail failure by either yield or fatigue is reported in fewer than 2–5% of clinical cases, the above analysis provides useful information on how fracture type and implant construct influence the maximum implant stress. Specifically in cases where a clinician suspects the patient may be slow to heal a fracture, such as with tobacco smokers and diabetics, the yield strength and fatigue life of the implant can become factors in mitigating fixation failure under the cyclic loads of gait.…”

Revision surgery due to failed internal fixation of intertrochanteric femoral fracture: current state-of-the-art

“…Additionally, they act as an intramedullary buttress to avoid excessive shaft medialization. Some advocates claim they have clinical benefits such as minimal surgical exposure, prevention of fracture hematoma, less blood loss, lower pain scores, improved functional ability and early mobilization [24,25]. Most recently, 20 failed intramedullary nail fixations were examined through 4 different revision procedures, including proximal femoral locking plates in 6 patients, intramedullary nails in 8 (40%) and prosthesis replacement in 6 [24].…”

“…Some advocates claim they have clinical benefits such as minimal surgical exposure, prevention of fracture hematoma, less blood loss, lower pain scores, improved functional ability and early mobilization [24,25]. Most recently, 20 failed intramedullary nail fixations were examined through 4 different revision procedures, including proximal femoral locking plates in 6 patients, intramedullary nails in 8 (40%) and prosthesis replacement in 6 [24]. According to the radiographic follow-up, fracture union in the repeated nailing group was observed at a mean period of 118.6 days, while the plate revision group required a longer time of 427.6 days.…”

Hip Fracture Nonunions: Diagnosis, Treatment, and Special Considerations in Elderly Patients

“…Unstable peritrochanteric femur fractures are recommended to be treated with distal interlocking screws for improved biomechanical properties, including torsional resistance [35]. Fracture reduction continues to be imperative for overall outcome, as fractures with “poor” reduction (varus malalignment on AP image, >20 degrees angulation on lateral image, or >4mm displacement) had significantly shorter time to failure than those with “adequate” or “good” reduction [39]. While choosing the correct implant specific to fracture morphology and obtaining a good reduction improve likelihood of fracture union, nonunions of peritrochanteric hip fractures unfortunately occur and various treatment options exist.…”

“…Additionally, if there is evidence of hip arthritis, THA is advocated [10, 11]. Depending on the amount of proximal femur bone stock remaining and prior stress risers along the shaft created by the previous fixation implant, a calcar-replacing implant, long stem implant, or a megaprosthesis (proximal femur replacement) may be required (Figure 2) [11, 39–41]. The majority of patients treated with calcar-replacing prostheses for intertrochanteric nonunion had significant reduction in pain and the returned ability to ambulate [40, 41].…”