What Are the Factors Associated With Revision Surgery on the Residual Limb and Functional Results in Patients With Posttraumatic Lower Limb Amputations?

Background: Lower limb amputations performed after trauma are associated with a high risk of revision surgery. While the factors influencing revision surgery in the upper limbs have been studied, no studies have analyzed these factors in the lower limbs. Existing explanations for these revision surgeries are unclear, often leaving patients uninformed. Surgeons also lack the tools to explain the factors that influence repeat operations to patients. Therefore, the aim of this study was to provide surgeons with some answers so they can inform their patients undergoing posttraumatic lower limb amputation, whether military or civilian.

Questions/purposes: (1) What was the survivorship of the initial amputation free from any revision surgery? (2) What patient- and injury-related factors were associated with revision amputation? (3) Do these factors influence functional outcomes in these patients?

Methods: A single-center, retrospective study was conducted between January 2010 and February 2020 on patients who had undergone traumatic lower limb amputation. Between January 2010 and February 2020, 322 patients underwent amputation or were followed up at Percy Military University Hospital. Thirty-one patients had undergone amputation at another center, 178 had undergone amputation for nontraumatic reasons, and 27 patients had only upper limb amputations. Of those remaining, 1 died before 6 months, and 6% (5 of 86) were not fitted with a prosthesis, leaving 99% (85 of 86) for survivorship free from revision analysis and 93% (80 of 86) for functional endpoints analysis in this retrospective study at a median of 6.5 years (IQR 5 to 9) following the index amputation. The median age at the time of amputation was 31 years (IQR 26 to 52), 85% (72 of 85) of patients were men, and 31% (26 of 85) were military personnel. Revision surgery was defined as surgery performed at or after 6 months to ensure that the residual limb was healed and fitted with a prosthesis. Revision procedures performed before 6 months (median 2 [IQR 0 to 7]) were considered as part of the initial residual limb formation surgery. We performed Kaplan-Meier survivorship analysis for the time free from revision amputation from 6 months after amputation. We considered the competitive risk of death using a Fine-Gray model by an ascending stepwise procedure. To answer our third research question, we performed a chart review and assessed patients' use of prostheses and assistive devices and the percentage of patients who returned to work. An ordinal logistic regression was used to analyze the factors influencing functional outcome using an ascending stepwise procedure.

Results: A total of 85 patients (94 limbs) were included, of whom 25 (27 limbs) underwent a revision surgery on the residual limb > 6 months after amputation. Kaplan-Meier survival estimates indicated that 5 years after the initial amputation 64% (95% confidence interval 53% to 77%) of the patients remained free from revision surgery on their residual limb. Factors associated with increased odds of revision amputation were smoking (subdistribution HR 2.6 [95% CI 1.2 to 5.8]; p = 0.02) and an age of > 50 years (subdistribution HR 0.3 [95% CI 0.1 to 0.8]; p = 0.01). Ninety-four percent (80 of 85) of patients were fitted with prostheses, and 40% (32 of 80) of patients used material or human assistance for simple activities of daily living. Seventy-one percent of patients (57 of 80) had returned to work. Ordinal logistic regression revealed an association between preinjury sports activity and the absence of need for assistance in daily activities (OR 9 [95% CI 2.9 to 31.8]; p < 0.001).

Conclusion: Smoking appeared to be an associated risk factor for residual limb revision surgery in posttraumatic lower limb amputations and is potentially modifiable. Being at least 50 years of age seemed to be associated with a lower incidence of revision surgery, which is probably linked to lower functional demands made on limbs beyond this age. Our study showed a remarkable rate of fitting with a prosthetic device, with an improved functional result if the patient was athletic before the trauma. These results provide more precise information on the care pathway to be considered for each patient. A study with a much larger sample would make it possible to assess the risk factors for the occurrence of each complication involving revision surgery.

Level of evidence: Level III, therapeutic study.