Osseointegrated reconstruction and rehabilitation of transtibial amputees: the Osseointegration Group of Australia surgical technique and protocol for a prospective cohort study

Transtibial osseointegration following unilateral traumatic amputation: An observational study of patients with at least two years follow-up

IMPORTANCE

Most patients use a traditional socket prosthesis (TSP) to ambulate independently following transtibial amputation. However, these patients generally require prosthesis repairs more than twice annually and an entirely new prosthesis every two years. Furthermore, transtibial amputation patients have four times the skin ulceration rate of transfemoral patients, prompting more frequent prosthesis refitting and diminished use. Trans-Tibial osseointegration (TTOI) is a promising technique to address the limitations of TSP, but remains understudied with only four cohorts totaling 41 total procedures reported previously. Continued concerns regarding the risk of infection and questions as to functional capacity postoperatively have slowed adoption of TTOI worldwide.

OBJECTIVE

This study reports the changes in mobility, quality of life (QOL), and the safety profile of the largest described cohort of patients with unilateral TTOI following traumatic amputation.

DESIGN

Retrospective observational cohort study. The cohort consisted of patients with data outcomes collected before and after osseointegration intervention.

SETTING

A large, tertiary referral, major metropolitan center.

PARTICIPANTS

Twenty-one skeletally mature adults who had failed socket prosthesis rehabilitation, with at least two years of post-osseointegration follow-up.

MAIN OUTCOMES AND MEASURES

Mobility was evaluated by K-level, Timed Up and Go (TUG), and Six Minute Walk Test (6MWT). QOL was assessed by survey: daily prosthesis wear hours, prosthesis problem experience, general contentment with prosthesis, and Short Form 36 (SF36). Adverse events included any relevant unplanned surgery such as for infection, fracture, implant loosening, or implant failure.

RESULTS

All patients demonstrated statistically significant improvement post osseointegration surgery with respect to K-level, TUG, 6MWT, prosthesis wear hours, prosthesis problem experience, general prosthesis contentment score, and SF36 Physical Component Score (p < 0.01 for all). Three patients had four unplanned surgeries: two soft tissue refashionings, and one soft tissue debridement followed eventually by implant removal. No deaths, postoperative systemic complications, more proximal amputations, or periprosthetic fractures occurred.

CONCLUSIONS AND RELEVANCE

TTOI is likely to confer mobility and QOL improvements to patients dissatisfied with TSP rehabilitation following unilateral traumatic transtibial amputation. Adverse events are relatively infrequent and not further disabling. Judicious use of TTOI seems reasonable for properly selected patients.

LEVEL OF EVIDENCE

2 (Therapeutic investigation, Observational study with dramatic effect).

Transcutaneous osseointegration for amputees

Transcutaneous osseointegration for amputees (TOFA) is an evolving technology that has the potential to revolutionize the interface between the amputee and their prosthesis, showing potential at many levels of amputation. While no amputation is without its challenges, TOFA requires a highly specialized prosthesis and a multidisciplinary team that includes specialized surgeons, physical therapists, wound care teams, and social workers who guide the amputee through surgery, postoperative rehabilitation, and the chronic wound care that goes into maintaining the prosthesis. The infrastructure required to facilitate care pathways that lead to reliable, successful outcomes are unique in each health care setting, including those in advanced health care systems such as the United States and Australia. This article details the emerging evidence supporting the use of this prosthetic interface design and many of the challenges that providers face when establishing programs to offer this type of care in the United States.

Development of an evidence-based diagnostic algorithm for infection in patients with transcutaneous osseointegration following amputation

Introduction: Transcutaneous osseointegration following amputation (TOFA) confers better mobility and quality of life for most patients versus socket prosthesis rehabilitation. Peri-TOFA infection remains the most frequent complication and lacks an evidence-based diagnostic algorithm. This study's objective was to investigate preoperative factors associated with positive intraoperative cultures among patients suspected of having peri-TOFA infection in order to create an evidence-based diagnostic algorithm. Methods: We conducted a retrospective study of 83 surgeries (70 patients) performed to manage suspected lower-extremity peri-TOFA infection at a specialty orthopedic practice and tertiary referral hospital in a major urban center. The diagnosis of infection was defined as positive intraoperative cultures. Preoperative patient history (fevers, subjective pain, increased drainage), physician examination findings (local cellulitis, purulent discharge, implant looseness), and laboratory data (white blood cell count, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and external swab culture) were evaluated for association with subsequent positive intraoperative cultures using regression and area under receiver-operator curve (AUC) modeling. Results: Peri-implant limb pain (highly correlated with infection), ESR > 30 (highly correlated against infection), positive preoperative swab (moderately correlated with infection), gross implant motion (moderately correlated against infection), and erythema or cellulitis of the transcutaneous region (mildly correlated with infection) were variables included in the best AUC model, which achieved an 85 % positive predictive value. Other clinical findings and laboratory values (notably CRP and WBC) were non-predictive of infection. Conclusions: This seminal investigation to develop a preoperative diagnostic algorithm for peri-TOFA infection suggests that the clinical examination remains paramount. Further evaluation of a wider spectrum of clinical, laboratory, and imaging data, consistently and routinely collected with prospective data techniques in larger cohorts of patients, is necessary to create a robust predictive algorithm.

External devices increasing bone quality in animals: A systematic review

Background: Osteoporosis can reduce bone quality and increase the risk of fractures. In addition to pharmacological approaches, physical activity, and implanted devices, external devices can also be detected in the literature as a technique to strengthen bones. This type of intervention arises to be particularly promising because it minimizes the invasiveness of therapy. Methods: A systematic review of the technologies involved in such devices was carried out to identify the most fruitful ones in improving bone quality. This review, according to the PRISMA Statement, focuses on studies involving animals, and excludes pharmaceutical approaches. Findings: The animal models and devices used, their settings, interventions, outcomes measured, and consequent effect on bone quality are reported for each detected technology. Ultrasound and laser arose to be the most studied technologies in the literature, even if they have yet to be proved to have a significant effect on bone quality. Interpretation: External devices for bone quality improvement offer a non-invasive approach that causes minimum discomfort to the patient. This review aimed to detect which technologies reported in the literature significantly affect bone quality. The results showed that several technologies are currently used to improve bone quality. However, each study measures different outcomes and uses different measurement methods, device settings, and interventions. This lack of standardization and the reduced number of articles found do not allow for proper quantitative comparisons.

Transcutaneous osseointegration for amputees with burn trauma

OBJECTIVE

Transcutaneous osseointegration for amputees (TOFA) surgically implants a prosthetic anchor into the residual limb's bone, enabling direct skeletal connection to a prosthetic limb and eliminating the socket. TOFA has demonstrated significant mobility and quality of life benefits for most amputees, but concerns regarding its safety for patients with burned skin have limited its use. This is the first report of the use of TOFA for burned amputees.

METHODS

Retrospective chart review was performed of five patients (eight limbs) with a history of burn trauma and subsequent osseointegration. The primary outcome was adverse events such as infection and additional surgery. Secondary outcomes included mobility and quality of life changes.

RESULTS

The five patients (eight limbs) had an average follow-up time of 3.8 ± 1.7 (range 2.1-6.6) years. We found no issues of skin compatibility or pain associated with the TOFA implant. Three patients underwent subsequent surgical debridement, one of whom had both implants removed and eventually reimplanted. K-level mobility improved (K2 +, 0/5 vs 4/5). Other mobility and quality of life outcomes comparisons are limited by available data.

CONCLUSION

TOFA is safe and compatible for amputees with a history of burn trauma. Rehabilitation capacity is influenced more by the patient's overall medical and physical capacity than their specific burn injury. Judicious use of TOFA for appropriately selected burn amputees seems safe and merited.

Design trends in actuated lower-limb prosthetic systems: a narrative review

INTRODUCTION

Actuated lower limb prostheses, including powered (active) and semi-active (quasi-passive) joints, are endowed with controllable power and/or impedance, which can be advantageous to limb impairment individuals by improving locomotion mechanics and reducing the overall metabolic cost of ambulation. However, an increasing number of commercial and research-focused options have made navigating this field a daunting task for users, researchers, clinicians, and professionals.

AREAS COVERED

The present paper provides an overview of the latest trends and developments in the field of actuated lower-limb prostheses and corresponding technologies. Following a gentle summary of essential gait features, we introduce and compare various actuated prosthetic solutions in academia and the market designed to provide assistance at different levels of impairments. Correspondingly, we offer insights into the latest developments of sockets and suspension systems, before finally discussing the established and emerging trends in surgical approaches aimed at improving prosthetic experience through enhanced physical and neural interfaces.

EXPERT OPINION

The ongoing challenges and future research opportunities in the field are summarized for exploring potential avenues for development of next generation of actuated lower limb prostheses. In our opinions, a closer multidisciplinary integration can be found in the field of actuated lower-limb prostheses in the future.

Bone density changes after five or more years of unilateral lower extremity osseointegration: Observational cohort study

Context

Rehabilitation following lower extremity amputation presents multiple challenges, many related to the traditional prosthesis (TP) socket. Without skeletal loading, bone density also rapidly decreases. Transcutaneous osseointegration for amputees (TOFA) surgically implants a metal prosthesis attachment directly into the residual bone, facilitating direct skeletal loading. Quality of life and mobility are consistently reported to be significantly superior with TOFA than TP.

Objective

To investigate how femoral neck bone mineral density (BMD, g/cm²) changes for unilateral transfemoral and transtibial amputees at least five years following single-stage press-fit osseointegration.

Methods

Registry review was performed of five transfemoral and four transtibial unilateral amputees who had dual x-ray absorptiometry (DXA) performed preoperatively and after at least five years. The average BMD was compared using Student's t-test (significance p < .05). First, all nine Amputated versus Intact limbs. Second, the five patients with local disuse osteoporosis (ipsilateral femoral neck T-score < -2.5) versus the four whose T-score was greater than -2.5.

Results

The average Amputated Limb BMD was significantly less than the Intact Limb, both Before Osseointegration (0.658 ± 0.150 vs 0.929 ± 0.089, p < .001) and After Osseointegration (0.720 ± 0.096 vs 0.853 ± 0.116, p = .018). The Intact Limb BMD decreased significantly during the study period (0.929 ± 0.089 to 0.853 ± 0.116, p = .020), while the Amputated Limb BMD increased a not statistically significant amount (0.658 ± 0.150 to 0.720 ± 0.096, p = .347). By coincidence, all transfemoral amputees had local disuse osteoporosis (BMD 0.545 ± 0.066), and all transtibial patients did not (BMD 0.800 ± 0.081, p = .003). The local disuse osteoporosis cohort eventually had a greater average BMD (not statistically significant) than the cohort without local disuse osteoporosis (0.739 ± 0.100 vs 0.697 ± 0.101, p = .556).

Conclusions

Single-stage press-fit TOFA may facilitate significant BMD improvement to unilateral lower extremity amputees with local disuse osteoporosis.

What Are Risk Factors for and Outcomes of Late Amputation After Treatment for Lower Extremity Sarcoma: A Childhood Cancer Survivor Study Report

BACKGROUND

Although pediatric lower extremity sarcoma once was routinely treated with amputation, multiagent chemotherapy as well as the evolution of tumor resection and reconstruction techniques have enabled the wide adoption of limb salvage surgery (LSS). Even though infection and tumor recurrence are established risk factors for early amputation (< 5 years) after LSS, the frequency of and factors associated with late amputation (≥ 5 years from diagnosis) in children with sarcomas are not known. Additionally, the resulting psychosocial and physical outcomes of these patients compared with those treated with primary amputation or LSS that was not complicated by subsequent amputation are not well studied. Studying these outcomes is critical to enhancing the quality of life of patients with sarcomas.

QUESTIONS/PURPOSES

(1) How have treatments changed over time in patients with lower extremity sarcoma who are included in the Childhood Cancer Survivor Study (CCSS), and did primary treatment with amputation or LSS affect overall survival at 25 years among patients who had survived at least 5 years from diagnosis? (2) What is the cumulative incidence of amputation after LSS for patients diagnosed with pediatric lower extremity sarcomas 25 years after diagnosis? (3) What are the factors associated with time to late amputation (≥ 5 years after diagnosis) in patients initially treated with LSS for lower extremity sarcomas in the CCSS? (4) What are the comparative social, physical, and emotional health-related quality of life (HRQOL) outcomes among patients with sarcoma treated with primary amputation, LSS without amputation, or LSS complicated by late amputation, as assessed by CCSS follow-up questionnaires, the SF-36, and the Brief Symptom Inventory-18 at 20 years after cancer diagnosis?

METHODS

The CCSS is a long-term follow-up study that began in 1994 and is coordinated through St. Jude Children's Research Hospital. It is a retrospective study with longitudinal follow-up of more than 38,000 participants treated for childhood cancer when younger than 21 years at one of 31 collaborating institutions between 1970 and 1999 in the United States and Canada. Participants were eligible for enrollment in the CCSS after they had survived 5 years from diagnosis. Within the CCSS cohort, we included participants who had a diagnosis of lower extremity sarcoma treated with primary amputation (547 patients with a mean age at diagnosis of 13 ± 4 years) or primary LSS (510 patients with a mean age 14 ± 4 years). The LSS cohort was subdivided into LSS without amputation, defined as primary LSS without amputation at the time of latest follow-up; LSS with early amputation, defined as LSS complicated by amputation occurring less than 5 years from diagnosis; or LSS with late amputation, defined as primary LSS in study patients who subsequently underwent amputation 5 years or more from cancer diagnosis. The cumulative incidence of late amputation after primary LSS was estimated. Cox proportional hazards regression with time-varying covariates identified factors associated with late amputation. Modified Poisson regression models were used to compare psychosocial, physical, and HRQOL outcomes among patients treated with primary amputation, LSS without amputation, or LSS complicated by late amputation using validated surveys.

RESULTS

More study participants were treated with LSS than with primary amputation in more recent decades. The overall survival at 25 years in this population who survived 5 years from diagnosis was not different between those treated with primary amputation (87% [95% confidence interval [CI] 82% to 91%]) compared with LSS (88% [95% CI 85% to 91%]; p = 0.31). The cumulative incidence of amputation at 25 years after cancer diagnosis and primary LSS was 18% (95% CI 14% to 21%). With the numbers available, the cumulative incidence of late amputation was not different among study patients treated in the 1970s (27% [95% CI 15% to 38%]) versus the 1980s and 1990s (19% [95% CI 13% to 25%] and 15% [95% CI 10% to 19%], respectively; p = 0.15). After controlling for gender, medical and surgical treatment variables, cancer recurrence, and chronic health conditions, gender (hazard ratio [HR] 2.02 [95% CI 1.07 to 3.82]; p = 0.03) and history of prosthetic joint reconstruction (HR 2.58 [95% CI 1.37 to 4.84]; p = 0.003) were associated with an increased likelihood of late amputation. Study patients treated with a primary amputation (relative risk [RR] 2.04 [95% CI 1.15 to 3.64]) and LSS complicated by late amputation (relative risk [RR] 3.85 [95% CI 1.66 to 8.92]) were more likely to be unemployed or unable to attend school than patients treated with LSS without amputation to date. The CCSS cohort treated with primary amputation and those with LSS complicated by late amputation reported worse physical health scores than those without amputation to date, although mental and emotional health outcomes did not differ between the groups.

CONCLUSION

There is a substantial risk of late amputation after LSS, and both primary and late amputation status are associated with decreased physical HRQOL outcomes. Children treated for sarcoma who survive into adulthood after primary amputation and those who undergo late amputation after LSS may benefit from interventions focused on improving physical function and reaching educational and employment milestones. Efforts to improve the physical function of people who have undergone amputation either through prosthetic design or integration into the residuum should be supported. Understanding factors associated with late amputation in the setting of more modern surgical approaches and implants will help surgeons more effectively manage patient expectations and adjust practice to mitigate these risks over the life of the patient.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Osseointegration for Lower-Extremity Amputees: Operative Considerations from the Plastic Surgeon's Perspective

➢

Osseointegration for lower-extremity amputees, while increasing in frequency, remains in its relative infancy compared with traditional socket-based prostheses.

➢

Ideal candidates for osseointegration have documented failure of a traditional prosthesis and should be skeletally mature, have adequate bone stock, demonstrate an ability to adhere to a longitudinal rehabilitation protocol, and be in an otherwise good state of health.

➢

Lowering the reoperation rate for soft-tissue complications depends heavily on surgical technique and on the implant device itself; the current gold standard involves a smooth implant surface for dermal contact as well as maximal skin resection to prevent skin breakdown against the prosthesis. This may include the need for thighplasty to optimize skin reduction.

➢

Interdisciplinary peripheral nerve management, such as targeted muscle reinnervation, performed in tandem with a plastic surgery team can treat existing and prevent future symptomatic neuromas, ultimately improving pain outcomes.

Association Between Osseointegration of Lower Extremity Amputation and Mortality Among Adults

IMPORTANCE

Transcutaneous osseointegration post amputation (TOPA) creates a direct linkage between residual bone and an external prosthetic limb, providing superior mobility and quality of life compared with a socket prosthesis. The causes and potential risks of mortality after TOPA have not been investigated.

OBJECTIVE

To investigate the association between TOPA and mortality and assess the potential risk factors.

DESIGN, SETTING, AND PARTICIPANTS

This observational cohort study included all patients with amputation of a lower extremity who underwent TOPA between November 1, 2010, and October 31, 2021, at a specialty orthopedic practice and tertiary referral hospital in a major urban center. Patients lived on several continents and were followed up as long as 10 years.

EXPOSURES

Transcutaneous osseointegration post amputation, consisting of a permanent intramedullary implant passed transcutaneously through a stoma and connected to an external prosthetic limb.

MAIN OUTCOMES AND MEASURES

Death due to any cause. The hypotheses tested-that patient variables (sex, age, level of amputation, postosseointegration infection, and amputation etiology) may be associated with subsequent mortality-were formulated after initial data collection identifying which patients had died.

RESULTS

A total of 485 patients were included in the analysis (345 men [71.1%] and 140 women [28.9%]), with a mean (SD) age at osseointegration of 49.1 (14.6) years among living patients or 61.2 (12.4) years among patients who had died. Nineteen patients (3.9%) died a mean (SD) of 2.2 (1.7) years (range, 58 days to 5 years) after osseointegration, including 17 (3.5%) who died of causes unrelated to osseointegration (most commonly cardiac issues) and 2 (0.4%) who died of direct osseointegration-related complications (infectious complications), of which 1 (0.2%) was coclassified as a preexisting health problem exacerbated by osseointegration (myocardial infarction after subsequent surgery to manage infection). No deaths occurred intraoperatively or during inpatient recuperation or acute recovery after index osseointegration (eg, cardiopulmonary events). Kaplan-Meier survival analysis with log-rank comparison and Cox proportional hazards regression modeling identified increased age (hazard ratio, 1.06 [95% CI, 1.02-1.09]) and vascular (odds ratio [OR], 4.73 [95% CI, 1.35-16.56]) or infectious (OR, 3.87 [95% CI, 1.31-11.40]) amputation etiology as risk factors. Notable factors not associated with mortality risk included postosseointegration infection and male sex.

CONCLUSIONS AND RELEVANCE

These findings suggest that patients who have undergone TOPA rarely die of problems associated with the procedure but instead usually die of unrelated causes.

Clinical Basis for Creating an Osseointegrated Neural Interface

As technology continues to improve within the neuroprosthetic landscape, there has been a paradigm shift in the approach to amputation and surgical implementation of haptic neural prosthesis for limb restoration. The Osseointegrated Neural Interface (ONI) is a proposed solution involving the transposition of terminal nerves into the medullary canal of long bones. This design combines concepts of neuroma formation and prevention with osseointegration to provide a stable environment for conduction of neural signals for sophisticated prosthetic control. While this concept has previously been explored in animal models, it has yet to be explored in humans. This anatomic study used three upper limb and three lower limb cadavers to assess the clinical feasibility of creating an ONI in humans. Anatomical measurement of the major peripheral nerves- circumference, length, and depth- were performed as they are critical for electrode design and rerouting of the nerves into the long bones. CT imaging was used for morphologic bone evaluation and virtual implantation of two osseointegrated implants were performed to assess the amount of residual medullary space available for housing the neural interfacing hardware. Use of a small stem osseointegrated implant was found to reduce bone removal and provide more intramedullary space than a traditional implant; however, the higher the amputation site, the less medullary space was available regardless of implant type. Thus the stability of the endoprosthesis must be maximized while still maintaining enough residual space for the interface components. The results from this study provide an anatomic basis required for establishing a clinically applicable ONI in humans. They may serve as a guide for surgical implementation of an osseointegrated endoprosthesis with intramedullary electrodes for prosthetic control.

Transtibial Osseointegration for Patients with Peripheral Vascular Disease: A Case Series of 6 Patients with Minimum 3-Year Follow-up

The management of peripheral vascular disease (PVD) can require amputation. Osseointegration surgery is an emerging rehabilitation strategy for amputees. In this study, we report on 6 patients who had PVD requiring transtibial amputation (PVD-TTA) and either simultaneous or subsequent osseointegration (PVD-TTOI).

Methods

Six patients (aged 36 to 84 years) with transtibial amputation and preexisting PVD underwent osseointegration between 2014 and 2016 and were followed for 3 to 5 years. Pre- and postoperative clinical and functional outcomes (pain, prosthesis wear time, mobility, walking ability, and quality of life) and adverse events (infection, fracture, implant failure, revision surgery, additional amputation, and death) were prospectively recorded.

Results

All patients' mobility improved following osseointegration. Three patients initially had required the use of a wheelchair, precluding baseline walking tests; the other 3 were classified as K level 1 or 2, with mean baseline Timed Up and Go (TUG) test = 14.0 ± 2.2 s and 6-Minute Walk Test (6MWT) = 262 ± 75 m. At the time of the latest follow-up, all patients were K level 2 or 3; mean TUG = 12.7 ± 7.2 s and 6MWT = 353 ± 148 m. Four patients wore their prosthesis ≥16 hours daily. Three patients had superficial soft-tissue infections. One other patient experienced recurrent infections 2.8 years after osseointegration requiring debridements and transfemoral amputation; the patient died 2 days following surgery from myocardial infarction caused by coronary atherosclerosis.

Conclusions

All 6 patients who underwent PVD-TTOI in this case series survived through 2 years. Patients who initially had used a wheelchair achieved and maintained independent, unaided ambulation until PVD-related impairments in the contralateral leg occurred in 1 patient. Patients previously using a traditional socket prosthesis reported improvement in mobility and quality of life. One patient's death underscores the importance of careful patient selection. However, marked improvement in the other 5 patients suggests cautious optimism that PVD-TTA is not an absolute osseointegration contraindication. Conscientious further investigation seems appropriate.

Level of Evidence

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Virtual implantation technique to estimate endoprosthetic contact of percutaneous osseointegrated devices in the tibia

Percutaneous osseointegrated (OI) devices have an endoprosthesis attached to the residual bone of an amputated limb, then pass permanently through the skin to be connected to the distal prosthetic componentry outside of the body. Whether the bone-anchoring region of current OI endoprostheses are cylindrical, and/or conical, they require intimate bone-endoprosthesis contact to promote stabilizing bone attachment. However, removing too much cortical bone to achieve more contact leads to thinner and, subsequently, weaker cortical walls. Endoprostheses need to be designed to balance these factors, namely maximizing the contact, while minimizing the volume of bone removed. In this study, 27 human tibias were used to develop and validate a virtual implantation method. Then, 40 additional tibias were virtually implanted with mock cylindrical and conical bone-anchoring regions at seven residual limb lengths to measure resultant bone-endoprosthesis contact and bone removal. The ratio of bone-endoprosthesis contact to bone volume removed showed the conical geometry had more contact area per volume bone removed for all amputation levels (p ≤ 0.001). In both mock devices, cortical penetration of the endoprosthesis at 20% residual length occurred in 74% of cases evaluated, indicating that alternative endoprosthesis geometries may be needed for clinical success in that region of bone.

Preoperative femoral abduction angle correlates with initial postoperative lateral hip pain after transcutaneous osseointegrated prosthetic system (TOPS) in transfemoral amputees

PURPOSE

To analyse whether a preoperative femoral abduction angle (FAA) correlates with postoperative initial lateral hip pain (LHP) in above-knee amputees (AKA) treated with transcutaneous osseointegrated prosthetic system (TOPS).

METHODS

Pre- and postoperative long-leg radiographs of eighteen unilateral AKA (mean age 51.55y ± 12.16) were retrospectively measured. FAA was measured on both sides. Pain intensity of LHP was measured by numeric rating scale (NRS) preoperatively and every week for four weeks from the first day of weight loading. Pearson's r was calculated for correlation. Furthermore, odds ratio for LHP ≥ 5/10 NRS and relative FAA > 13° was calculated.

RESULTS

FAA significantly decreased in the postoperative period (pre/post. 15.33° ± 4.22; p < 0.001). Median LHP was 0/10 NRS (min.0, max.3) preoperatively and 4/10 NRS (min.2, max. 7, p < 0.001) postoperatively after first loading. Interestingly, it decreased within four weeks to a median of 0.5/10 NRS (min.0, max. 3) without intervention. A strong correlation was seen on the amputated side between preoperative FAA and LHP after loading (r = 0.835, p < 0.001), as well as the relative FAA to LHP after loading (r = 0.732, p < 0.001) and between the gap of pre- to postoperative FAA and LHP. Odds ratio for LHP ≥ 5/10 and relative FAA > 13° was 6.4 (95%CI = 0.55; 74.89).

CONCLUSION

The preoperative FAA strongly correlates with postoperative LHP. Surgeons should be aware of high risk of LHP that can limit prosthetic training. High preoperative FAAs should be realised in the decision meeting of TOPS implantation and pre-rehabilitative reduction of the FAA should be taken into consideration.