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.

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.

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.

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.

Osseointegration Following Transfemoral Amputation After Infected Total Knee Replacement: A Case Series of 10 Patients With a Mean Follow-up of 5 Years.

Background: Management of total knee replacement (TKR) infection may sometimes prompt knee fusion (KF) or transfemoral amputation (TFA), both associated with low mobility and quality of life (QOL). Transcutaneous osseointegration for amputees provides superior mobility and QOL vs traditional socket prostheses but has not been studied for patients with a history of infected TKR. This study investigates the following hypothesis: Patients who have had TFA or KF following infected TKR achieve better mobility and QOL following transfemoral osseointegration. Material and methods: A retrospective evaluation of the prospectively maintained registry identified 10 patients who had prior infected TKR. The mobility assessments (patient daily prosthesis wear time, K-level, Timed Up and Go, 6-Minute Walk Test) and QOL surveys (Questionnaire for Persons with a Transfemoral Amputation Global, Mobility, and Problem scores) were compared preoperatively and after at least 2 years. Complications requiring an additional surgery were also evaluated. Results: Daily wear hours, K-level, and 6-Minute Walk Test and Questionnaire for Persons with a Transfemoral Amputation Global and Problem scores significantly improved (P < .05). Through 1 year, 4 patients (40%) had additional surgeries. After several years, 7 patients (70%) had at least 1 additional surgery, and 5 (50%) had multiple, for an average of 1 debridement and 1.3 soft-tissue refashionings per patient. One patient died of newly diagnosed cancer 1 year after transcutaneous osseointegration for amputees. Conclusion: Transfemoral osseointegration confers significantly better mobility and QOL vs KF or a TFA with traditional socket prostheses following infected TKR. Technique improvements to prevent subsequent surgeries may provide an increasingly streamlined experience.