Long-term outcomes of distal locking in extracapsular fractures treated with trochanteric Gamma3 nails

Abstract

Background: Few publications have assessed long-term results of distal locking of short endomedullary nails for extracapsular hip fracture. Virtually all of them focus on immediate differences. Criteria for the use of static or dynamic locking are unclear in most nailing systems, and use is advised in unstable fracture patterns or with risk of bell-clapper effect, but often influenced by the "orthopaedic school".

Materials and methods: This is a historical cohort study on patients diagnosed and operated in 2014 and followed up until endpoint, considered as consolidation or major complication, plus evaluation of overall long-term survival. They were categorised as static distal locking (ST) or dynamic distal locking (DN). Both are comparable, except for all stable pre-operative classifications, Fracture Mobility Score (FMS) at discharge, and immediate post-operative loading, all of which were in favour of DN.

Results: Consolidation took place in > 95% of patients, with a non-statistically significant delay trend in ST. Less than 6% in both ST and DN had major complications, with no differences. Most cases suffered early cut-out. Significant fracture collapse was the most frequent minor complication. There were more statistically significant minor and total complications in ST. Infection, without differences, can precede cut-out. Lateral thigh pain was similar and could be related to back-out. In DN, 21.1% of cases were truly dynamised. We did not find differences in mobility or in long-term survival.

Conclusions: Any type of distal locking seems to be safe for consolidation, despite a slightly longer consolidation time in static locking. Early cut-out was the main complication, while others were very infrequent, which is an advantage over helical blade devices. There was a higher rate of minor and overall mechanical complications in ST, but infection and lateral thigh pain were similar. Most non-traumatic mechanical complications occurred around 5-6 weeks. About one in five of the DN truly dynamised, with all cases occurring before 8 weeks. Mobility until endpoint and overall long-term survival were not influenced by the locking mode used.

Level of evidence: Therapeutic study, level 2b.

Keywords: Consolidation; Cut-out; Distal locking; Gamma3; Intertrochanteric fracture; Mechanical complications; Risk factor.

Fig. 1

Organisation chart. ECF, extracapsular fracture; HUS, Hospital Universitario de Salamanca; Sx., surgery; POS, poor overall status; THA, total hip arthroplasty; ST, static locking mode; DN, dynamic locking mode; UL, unlocked mode

Fig. 2

Patients’ mobility (Fisher’s exact test). FMS, Fracture Mobility Score

Fig. 3

Patients’ survival