How To Improve Patient Selection in Individuals With Lower Extremity Amputation Using a Bone-anchored Prosthesis
Authors: van Vliet-Bockting Charlotte , Atallah Robin , Frölke Jan Paul M. , Leijendekkers Ruud A. 
Published: January 2025

Background
Many patients with a lower limb socket-suspended prothesis experience socket-related problems, such as pain, chronic skin conditions, and mechanical problems, and as a result, health-related quality of life (HRQoL) is often negatively affected. A bone-anchored prosthesis can overcome these problems and improve HRQoL, but these prostheses have potential downsides as well. A valid and reliable tool to assess potential candidates for surgery concerning a favorable risk-benefit ratio between potential complications related to bone-anchored prostheses and improvements in HRQoL is not available yet. Having this information may inform treating physicians and patients when deciding whether to pursue bone-anchored prostheses.

Questions/purpose
In this study, we asked: (1) What is the difference in HRQoL at 6, 12, and 24 months among patients who underwent lower limb bone-anchored prosthesis treatment after using a socket-suspended prosthesis preoperatively? (2) What factors are associated with change in HRQoL 24 months after lower limb bone-anchored prosthesis treatment? (3) Which complications occurred within 24 months after lower limb bone-anchored prosthesis treatment? (4) What factors are associated with minor to severe complications within 24 months after lower limb bone-anchored prosthesis treatment?

Methods
A total of 206 patients who underwent lower limb bone-anchored prosthesis treatment (femoral or tibial) at the Radboud University Medical Center between May 2014 and September 2020 were included in this study. Of those, 8% (17 of 206) were lost to follow-up at 24 months without meeting a study endpoint (not attending the clinic unrelated to the bone-anchored prosthesis, re-amputation), and another < 1% (1 of 206) died prior to 24 months, leaving 92% (189 of 206) of the original group who had a follow-up time of at least 24 months. The mean ± SD age was 54.3 ± 12.7 years, and 72% were men. Amputation levels included 64% (139 of 218) transfemoral amputation, 3% (7 of 218) knee exarticulation, 32% (70 of 218) transtibial amputation, 0.5% (1 of 218) foot amputation, and 0.5% (1 of 218) osseointegration implant after primary amputation. Causes of amputation included 52% (108 of 206) trauma, 8% (17 of 206) oncology, 19% (38 of 206) dysvascular, 12% (25 of 206) infection, 1% (2 of 206) congenital, and 8% (16 of 206) other. Primary outcomes were generic HRQoL (Short-Form 36 health survey mental component summary [MCS] and physical component summary [PCS] scores), disease-specific HRQoL (Questionnaire for Persons with a Transfemoral Amputation global score), and complication occurrence (infection, implant complications such as loosening or breakage, stoma-related problems, periprosthetic fracture, and death). Multivariable multiple regression was used to develop association models. These models demonstrated which group of characteristics were associated with change in HRQoL at 24 months of follow-up and occurrence of complications within 24 months of follow-up. Assessments were carried out at baseline (preoperative while using a socket-suspended prosthesis) and after 6, 12, and 24 months of bone-anchored prosthesis use.

Results
Generic HRQoL PCS score improved 25% (β 9 [95% confidence interval (CI) 7 to 11]) at 6 months and maintained that improvement at the 12-month (β 9 [95% CI 7 to 11]) and 24-month (β 8 [95% CI 7 to 10]) follow-up visit compared with baseline (p < 0.001). The generic HRQoL MCS score did not change compared with baseline. Disease-specific HRQoL improved 77% (β 30 [95% CI 25 to 34]), 85% (β 33 [95% CI 28 to 37]), and 72% (β 28 [95% CI 24 to 33]) at 6-month, 12-month, and 24-month follow-up, respectively, compared with baseline (p < 0.001). Patients with the following group of characteristics were more likely to experience a better physical generic HRQoL at 24 months of follow-up: younger patients with a lower physical generic HRQoL, and a traumatic cause of amputation combined with a lower activity level. Patients with the following group of characteristics were more likely to experience a better disease-specific HRQoL at 24 months of follow-up: dysvascular cause of amputation, lower prosthetic comfort combined with a lower activity level, and lower prosthetic comfort combined with a lower or higher activity level. In addition, patients with an average mobility level were more likely to experience less improvement in disease-specific HRQoL at 24 months of follow-up. Infections were the most common complications in the total cohort (116 events in 206 patients), of which the majority consisted of soft tissue infections (98% [114 of 116]). Bone infection did not occur. Septic implant loosening occurred in 1% (2 of 214) of total implants (3% [2 of 66] of tibial implants), both treated with transfemoral amputation. Younger and higher functioning patients had the lowest risk of minor complications within 24 months of follow-up. Women, older patients, patients with a lower activity level, and older patients with more time since amputation had the highest risk of minor complications within 24 months of follow-up. Patients with a higher disease-specific HRQoL had the highest risk of moderate or severe complications within 24 months of follow-up.

Conclusion
In agreement with earlier research, this study confirmed that generic HRQoL and disease-specific HRQoL improved after bone-anchored prosthesis use. Additionally, this study confirmed that bone-anchored prosthesis has a relatively low likelihood of severe complications but with a high occurrence of minor complications. These were often successfully treated with nonsurgical interventions. Patients who have a favorable risk-benefit ratio between improvements in HRQoL and potential treatment-related complications are most eligible for a bone-anchored prosthesis. These findings may be helpful to patients and treating physicians to aid in patient selection and to inform patients about potential short-term expectations of treatment.

Level of Evidence
Level III, therapeutic study.