Prognostic Factors for Attempted Finger Replantation and Revascularisation after Traumatic Amputation: A 16-Year Retrospective Cohort Study.

Background: The aim of this study was to evaluate the impact of variant factors on finger replantation and revascularisation after traumatic amputation, which also included duty shift and the level of main operator. Methods: To determine the prognostic factors for the survival rate of finger replantation and revascularisation after traumatic finger amputation, we retrospectively reviewed the cases of finger replantation conducted from January 2001 to December 2017. Data collected consisted of the basic information of the patients, trauma-related factors, details of the operation and treatment outcomes. Descriptive statistics and data analysis was performed to assess outcomes. Results: In total, 150 patients with 198 replanted digits were enrolled in this study. The median age of the participants was 42.5 years, and 132 (88%) patients were men. The overall successful replantation rate was 86.4%. Seventy-three (36.9%) digits had Yamano type 1 injury; 110 (55.6%), Yamano type 2 injury and 15 (7.6%), Yamano type 3 injury. In total, 73 (36.9%) digits were completely amputated and 125 (63.1%) were not. Half of the replantation procedures (101, 51.0%) were performed during night shift (16:00-00:00), 69 (34.8%) during day shift (08:00-16:00) and 28 (14.1%) during graveyard shift (00:00-08:00). Multivariate logistic regression demonstrated that the trauma mechanism and type of amputation (complete vs. incomplete) significantly affect the survival rate of replantation. Conclusions: The trauma mechanism and type of amputation (complete vs. incomplete) significantly affect the survival rate of replantation. Other factors including duty shift and the level of operator did not reach statistically significance. Further studies must be conducted to validate the results of the current study. Level of Evidence: Level III (Prognostic).

Traumatic Amputation From a Rollover Farming Incident in a 16-Year-Old.

There is very little literature on the overall management of adolescent traumatic amputation, specifically of the lower extremity. We present a case involving an adolescent patient involved in an industrial farm tractor rollover with substantial crush and degloving injuries requiring bilateral lower extremity amputations. The patient was initially assessed and acutely managed in the field before arriving at an adult level 1 trauma center having two right lower extremity tourniquets already applied and a pelvic binder in place. During his hospitalization, he was revised to bilateral above-knee amputations that required multiple debridements prior to being transferred to a pediatric trauma center due to the extent of the soft tissue injury and need for flap coverage. Our adolescent patient presented with an uncommon injury mechanism resulting in significantly mangled lower extremities highlighting the importance of a multidisciplinary approach in all aspects of the patient's prehospital, intrahospital, and posthospital care.

Predictors for Necrosis after Single-Digit Replantation: A Retrospective Analysis of 946 Patients.

BACKGROUND: Digital necrosis (DN) is a serious complication after replantation. However, predisposing factors, as reported less, remain controversial. The purpose of this study was to explore risk factors of necrosis after single-digit replantation by means of a retrospective study. METHODS: Patients who underwent single-digit replantations in our hospital between June of 2014 and October of 2020 were included. The authors regarded DN as the failure group and digital survival as the success group. The factors were conducted by univariate and multivariate analysis. RESULTS: The survival rate in our study was 78.8% (745 of 946). The results of univariate analysis showed that there were significant differences in the levels of D-dimer (first), menstrual cycle, injury level, and starting and finishing time of surgery between different groups. In multivariate analysis, age, injury level, duration of surgery, and D-dimer (first) were identified as the risk factors for DN in the entire and male population. In addition, regarding male patients, ischemia time was also found to be a risk factor for DN. In terms of female patients, the menstrual period and menopause were related to DN. CONCLUSIONS: Many factors, including age, ischemia time, injury level, menstrual period, menopause, and duration of surgery, were related to DN after digital replantation. D-dimer (first) was first found as a predicted factor for DN. In addition, these results also showed that the starting and ending times of surgery were associated with DN by univariate analysis. Preoperative measures should be taken to lower the incidence of DN. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Is Prolonged Use of Antibiotic Prophylaxis and Postoperative Antithrombotic and Antispasmodic Treatments Necessary After Digit Replantation or Revascularization?

BACKGROUND: Ensuring the patency of repaired vessels is pivotal in improving the success rate of digit replantation. There is no consensus on how to best approach postoperative treatment for digit replantation. The influence of postoperative treatment on the risk of failure of revascularization or replantation remains unclear. QUESTIONS/PURPOSES: (1) Is there an increased risk of postoperative infection with early discontinuation of antibiotic prophylaxis? (2) How are anxiety and depression affected by a treatment protocol consisting of prolonged antibiotic prophylaxis and administration of antithrombotic and antispasmodic drugs and by the failure of a revascularization or replantation procedure? (3) Are there differences in the risk of revascularization or replantation failure based on the number of anastomosed arteries and veins? (4) What factors are associated with failure of revascularization or replantation? METHODS: This retrospective study was conducted between July 1, 2018, and March 31, 2022. Initially, 1045 patients were identified. One hundred two patients chose revision of amputation. In all, 556 were excluded because of contraindications. We included all patients in whom the anatomic structures of the amputated part of the digit were well preserved, and those with an ischemia time for the amputated part that did not exceed 6 hours. Patients in good health without any other serious associated injuries or systemic diseases and those without a history of smoking were eligible for inclusion. The patients underwent procedures that were performed or supervised by one of four study surgeons. Patients were treated with antibiotic prophylaxis (1 week); patients treated with antithrombotic and antispasmodic drugs were categorized into the prolonged antibiotic prophylaxis group. The remaining patients treated with antibiotic prophylaxis for less than 48 hours and no antithrombotic and no antispasmodic drugs were categorized into the nonprolonged antibiotic prophylaxis group. Postoperative follow-up was for a minimum of 1 month. Based on the inclusion criteria, 387 participants with 465 digits were selected for an analysis of postoperative infection. Twenty-five participants with a postoperative infection (six digits) and other complications (19 digits) were excluded from the next stage of the study, in which we assessed factors associated with the risk of failure of revascularization or replantation. A total of 362 participants with 440 digits were examined, including the postoperative survival rate, variation in Hospital Anxiety and Depression Scale scores, the association between the survival rate and Hospital Anxiety and Depression Scale scores, and the survival rate based on the number of anastomosed vessels. Postoperative infection was defined as swelling, erythema, pain, purulent discharge, or a positive bacterial culture result. Patients were followed for 1 month. The differences in anxiety and depression scores between the two treatment groups and the differences in anxiety and depression scores based on failure of revascularization or replantation were determined. The difference in the risk of revascularization or replantation failure based on the number of anastomosed arteries and veins was assessed. Except for statistically significant variables (injury type and procedure), we thought that the number of arteries, number of veins, Tamai level, treatment protocol, and surgeons would be important. A multivariable logistic regression analysis was used to perform an adjusted analysis of risk factors such as postoperative protocol, injury type, procedure, number of arteries, number of veins, Tamai level, and surgeon. RESULTS: Postoperative infection did not appear to increase without prolonged use of antibiotic prophylaxis beyond 48 hours (1% [3 of 327] versus 2% [3 of 138]; OR 2.4 [95% confidence interval (CI) 0.5 to 12.0]; p = 0.37). Intervention with antithrombotic and antispasmodic therapy increased the Hospital Anxiety and Depression Scale scores for anxiety (11.2 ± 3.0 versus 6.7 ± 2.9, mean difference 4.5 [95% CI 4.0 to 5.2]; p < 0.01) and depression (7.9 ± 3.2 versus 5.2 ± 2.7, mean difference 2.7 [95% CI 2.1 to 3.4]; p < 0.01). In the analysis based on the failure of revascularization or replantation, the Hospital Anxiety and Depression Scale scores for anxiety (11.4 ± 4.4 versus 9.7 ± 3.5, mean difference 1.7 [95% CI 0.6 to 2.8]; p < 0.01) and depression (8.5 ± 4.6 versus 7.0 ± 3.1, mean difference 1.5 [95% CI 0.5 to 2.5]; p < 0.01) were higher in the failed revascularization or replantation group than in the successful revascularization or replantation group. There was no increase in the artery-related risk of failure (one versus two anastomosed arteries: 91% versus 89%, OR 1.3 [95% CI 0.6 to 2.6]; p = 0.53). For patients with anastomosed veins, a similar outcome was observed for the two vein-related risk of failure (two versus one anastomosed vein: 90% versus 89%, OR 1.0 [95% CI 0.2 to 3.8]; p = 0.95) and three vein-related risk of failure (three versus one vein anastomosed: 96% versus 89%, OR 0.4 [95% CI 0.1 to 2.4]; p = 0.29). Factors associated with failure of revascularization or replantation included the mechanism of injury (crush: OR 4.2 [95% CI 1.6 to 11.2]; p < 0.01, avulsion: OR 10.2 [95% CI 3.4 to 30.7]; p < 0.01). Revascularization had a lower risk of failure than replantation (OR 0.4 [95% CI 0.2 to 1.0]; p = 0.04). Treatment with a protocol of prolonged antibiotics, antithrombotics, and antispasmodics was not associated with a lower risk of failure (OR 1.2 [95% CI 0.6 to 2.3]; p = 0.63). CONCLUSION: With proper wound debridement and patency of repaired vessels, prolonged use of antibiotic prophylaxis and regular antithrombotic and antispasmodic treatment may not be necessary for successful digit replantation. However, it may be associated with higher Hospital Anxiety and Depression Scale scores. Postoperative mental status is associated with digit survival. Well-repaired vessels, instead of the number of anastomosed vessels, could be critical to survival and decrease the influence of risk factors. Further research on consensus guidelines that compare postoperative treatment and the surgeon's level of expertise after digit replantation should be conducted at multiple institutions. LEVEL OF EVIDENCE: Level III, therapeutic study.

The challenges and complications of re-implantation of the penis following amputation.

Amputation of the penis is a rare and devastating injury. The etiologies vary from accidental, self-inflicted to attacks due to sexual jealousy and revenge. In the present era of microvascular surgery, replantation is the standard care. However, replantation of the penis comes with its own set of difficulties and complications. Knowledge of the anatomy and prior knowledge of the possible complications makes the surgeon aware of the course of events after a replantation. It helps in devising strategies to overcome these challenges methodically. We present a case of penile replant with the complications that we encountered, and the measures are taken to counter them on our way to a successful outcome. Funding: No external funding.

Rodeo Thumb: To Replant or Not.

BACKGROUND: This study investigated patient-reported outcomes after surgical treatment of rodeo thumb amputation to guide clinical decision-making. METHODS: A retrospective review was performed for rodeo thumb amputations from 2009 to 2019. Patient-reported outcomes were collected and compared by injury level, age, and treatment. Two-sided t test was used to compare continuous variables, and Pearson chi-square test was used to compare categorical data. RESULTS: The study included 37 patients. Patients with interphalangeal injuries treated with replantation had Quick Disabilities of the Arm, Shoulder and Hand questionnaire scores similar to those treated with amputation (1 versus 8; p = 0.07). There was no significant difference in percentage of patients with similar or better roping ability after treatment (40 percent versus 79 percent; p = 0.26), and similar percentages were satisfied (80 percent versus 71 percent; p = 1.00). Patients with metacarpophalangeal injuries treated with replantation and those treated with amputation had similar questionnaire scores (7 versus 10; p = 0.47). Both groups had similar roping ability after treatment (67 percent versus 56 percent; p = 1.00), and there was no statistically significant difference in satisfaction (79 percent versus 44 percent; p = 0.34). Pediatric patients had questionnaire scores similar to those of adults (6 versus 8; p = 0.42). A significantly higher percentage of pediatric patients had similar roping ability following injury than adults (100 percent versus 54 percent; p = 0.02). Most patients in both groups were satisfied (89 percent versus 61 percent; p = 0.22). CONCLUSIONS: For both interphalangeal and metacarpophalangeal injuries, patient-reported outcomes were similar regardless of treatment. Children were able to return to roping and perform at a similar or higher level at a greater rate than adults, but had similar questionnaire scores and satisfaction.

Epidemiology of Upper-Extremity Amputations Using the National Electronic Injury Surveillance System.

BACKGROUND: Upper-extremity amputations can be devastating injuries that lead to lifelong disabilities. The purpose of our study was to review national data and identify populations at risk and injury patterns that could be targeted with prevention strategies. METHODS: Data from the National Electronic Injury Surveillance System between years 2012 and 2018 were reviewed. Injuries affecting the upper extremity resulting in amputation were included. Patient demographics, anatomical location, mechanism of injury, level of care provided, and setting of injury were recorded. Descriptive was recorded and tabulated for each category. RESULTS: There were 4,766 patients identified with amputations to the upper extremity from 2012 to 2018. The following categories are listed below: age in years, sex, race, anatomical location of injury, most common mechanisms of injury, disposition of patient, environmental location. CONCLUSIONS: Our data show that male children younger than 10 years are at the high risk for finger amputations. In addition, the majority of these injuries occur in the home. This suggests that safety prevention in the home is a significant area in need of improvement. We recommend further research in areas of home safety and injury prevention to decrease the risk of the devastating injuries.

Do Not Cut Wood with an Angle Grinder, or You Might Lose a Finger: A Retrospective Study.

Background: Angle grinders are a handheld power tool used for grinding and polishing stone, metal, and concrete. Some people, however, use them with a circular saw blade attachment for cutting wood and consequently, suffer injuries. We aimed to investigate the underlying cause and mechanisms of injuries caused by cutting wood with an angle grinder. Methods: We conducted a retrospective study using medical records from our trauma center and identified 15 patients treated for angle grinder injury between 2017 and 2018. Moreover, we contacted the National Consumer Affairs Center of Japan for further information about angle grinder injuries. Results: Nine of the 15 patients used angle grinders improperly, of which only three patients were aware of the risk of injury. The details of the nine patients were as follows: the types of injuries: complete finger amputation (n = 2), partial finger amputation (n = 1), tendon injury with phalangeal fracture (n = 5), and tendon injury alone, (n = 1); the causes of accidents: kickback (n = 7) and glove entanglement (n = 2); and the accident situations: on-the-job (n = 5) and do-it-yourself (n = 4). Conclusions: The primary cause of angle grinder injury caused by cutting wood was a lack of user knowledge that an angle grinder cannot be used as a cutting tool. Appropriate feedback from hand surgeons are necessary to urge manufacturers to take safety measures.

Replantation for multiple digit amputations: A retrospective analysis of the clinical results.

PURPOSE: Replantation of multidigit amputations is difficult to perform due to severe damage to the digits, prolonged operative time, and ischemia. This study aimed to report the clinical results of multidigit replantation. METHODS: A retrospective case series of 34 digits belonging to 12 consecutive patients who underwent multidigit replantation was conducted. Patients with injury in at least one or more amputated fingers proximal to the insertion of the flexor digitorum superficialis tendon were included. The mean follow-up duration was 18.1 months. The number of amputated digits, mechanism and zone of injury, survival rate, and clinical outcomes, including the range of motion, grip strength, and sensory recovery, at the final follow-up were reviewed and analyzed. RESULTS: The mean number of amputated digits per patient was 2.8. Complete survival was achieved in 27 of 31 digits (87.1%). The mean final percentage of total active motion of injured digits was 47.0%, and the mean percentage of grip strength was 45.9% of the contralateral uninjured side. The comparison between patients with two and three amputated digits showed that there was no significant difference in both survival rates and functional outcomes. CONCLUSIONS: The results showed that both the survival rates and functional outcomes of multidigit replantation were as good as those of single-digit replantation, and there was no significant difference for outcomes between patients with two and three amputated digits. These results suggested that all multidigit replantations should be performed regardless of the number of injured digits or amputation zones.

Domestic donkey bite of genitalia: an unusual etiology of penile glans amputation in Burkina Faso (case report and literature review).

A 15-years-old boy was admitted in our hospital emergency unit with complaints of injured and hemorrhagic penile glans after donkey bites. The accident occurred during domestic activity with the animal when the boy attempted to guide the donkey. After thorough physical examination, the patient presented a penile glans amputation. Tetanic prophylaxis was started. The patient benefited from hemostatic suturing, stump regularization and penile glans reconstructive surgery and there was no complication. Functional and cosmetic results were satisfactory with good quality of micturition after six months' follow-up.

Traumatic complete outer ear amputation by human bite, a forensic case report and review of the literature.

We present a case of a complete external ear amputation, caused by a human bite, that took place during a quarrel in a local farmers' market. The male victim was transferred to the Hospital. After surgical reattachment of the auricle, a forensic clinical examination was performed, as per legal obligation. During examination, the victim was found to have sustained: contusions of the orbital regions (lower eyelids), bilaterally, soft tissue oedema of the forehead (to the left of the middle line), and contusion of the right neck area. He also sustained multiple soft tissue injuries (contusions, abrasions) on the torso and on both upper and lower extremities. Clinical forensic examination of human bite injuries requires thorough description of the wound, proper photography and possibly collection of swabs for DNA identification (in case of unknown perpetrator). Nevertheless, the Forensic Pathologist is often required to perform clinical examination, only after medical care has been provided. Therefore, clinicians should be aware of the need of proper documentation and act accordingly.

Firework Injuries of the Hand: An Analysis of Treatment and Health Care Utilization.

Background: Firework injuries to the hand can be devastating due to the explosive and ballistic nature of these devices. The aim of this study was to describe the injury and treatment characteristics of patients requiring surgery for firework-related hand injuries and to investigate which factors are associated with an increased utilization of health care resources. Methods: A retrospective chart review of patients undergoing surgery for firework-related hand injuries at two American College of Surgeons level I trauma centers between 2005 and 2016 was performed. Twenty cases were identified. These patients were evaluated for demographics, injury characteristics, number and types of surgical interventions, length of stay, and utilization of health care resources. Bivariate analyses were performed to investigate which factors were associated with increased consumption of health care resources. Results: Injuries ranged from digital nerve injuries to traumatic amputation. Patients underwent a median of 3 surgical operations. More than half the patients underwent flap or skin graft coverage of a soft tissue defect. The median length of hospital stay was 7 days. Factors found to be associated with an increased utilization of surgical and hospital resources included a first web space injury, thumb fracture, and traumatic amputation of any digit. Conclusions: The morbidity inflicted by firework injuries to individual patients is substantial. Patients with severe injuries undergo a median of three surgical operations and have a long duration of initial hospital stay. Knowing which factors are associated with an increased utilization of resources can help prognosticate these preventable injuries.

A Rare Case of First Metatarsal Extrusion: Results of Treatment After 12 Months.

We present the case of a 21-year-old male with 12 months' follow-up after reimplantation of a completely extruded first metatarsal. The patient had a motorcycle accident involving his right foot and ankle, with multiple lesser metatarsal fractures, lateral malleolus fracture, and a total first metatarsal extrusion (without fracture) through a large dorso-medial forefoot wound. The extruded bone was recovered at the site of the motor vehicle accident and was transported to the hospital with the patient. Before the reimplantation surgery was undertaken, the first metatarsal was immersed in a chlorhexidine solution for 20 minutes and then washed in an antibiotic solution. Metatarsal fixation was performed with Kirschner wires; the lateral malleolus fracture was fixed with plate and screws. An external fixator was then applied. Throughout the 12-month follow-up period, there was no evidence of infection. At the present time, this case suggests that, after antiseptic cleansing and prompt surgery, extruded first metatarsal reimplantation is possible with a reasonable degree of clinical success.

Complications of high volume circumcision: glans amputation in adolescents; a case report.

BACKGROUND: The past four years has seen a rapid roll-out of male medical circumcision services in South Africa in response to clinical trials showing circumcision prevents HIV acquisition in heterosexual men. Clinics conduct substantial numbers of circumcisions per day. We report three cases of glans amputation in adolescents attending high volume clinics where modified Models of Optimising Volume and Efficiency (MOVE) are implemented. CASE PRESENTATIONS: Three cases of glans amputation in young healthy men that presented for voluntary medical male circumcision. The procedures were performed by highly experienced medical officers in two cases. All these cases shared characteristics: younger males with immature genitalia, forceps guided circumcision, and likely operator fatigue. Voluntary male medical circumcision programs should include regular monitoring and evaluation and training of operators to ensure high quality surgical techniques such as working in clean areas and taking frequent breaks. CONCLUSION: Circumcision is a relatively simple medical procedure, however regular training and quality control in high volume Male Medical Circumcision sites is essential to prevent rare catastrophic adverse events.

Glandular amputation by strangulating tied suture: a case report of late-onset complication in the Plastibell circumcision technique.

BACKGROUND: Circumcision is considered to be a procedure with minimal morbidity but may be associated with catastrophic complications in inexpert hands. CASE PRESENTATION: We presented a 9-year-old boy with a past medical history of circumcision at the age of one year with Plastibell clamp who was referred with severe chronic penile injury due to neglected plastibell string. After string removal under a loupe magnification (4×), we saw a deep circular injury at distal penile shaft which led to painless glandular autoamputation 45 days later. The patient was managed conservatively with daily urethral self-dilation until future reconstructive surgery. CONCLUSION: This complication emphasized the importance of the follow-up visit by a physician for any probable string remnant.

Traumatic amputations caused by drone attacks in the local population in Gaza: a retrospective cross-sectional study.

BACKGROUND: Little data exist to describe the use and medical consequences of drone strikes on civilian populations in war and conflict zones. Gaza is a landstrip within the Palestinian territories and the home of 2 million people. The median age in Gaza is 17·2 years and almost half of the population is below the age of 14 years. We studied the prevalence and severity of extremity amputation injuries caused by drone strikes compared with those caused by other explosive weapons among patients with amputations attending the main physical prosthesis and rehabilitation centre in Gaza. METHODS: In this retrospective cross-sectional study, we recruited patients from the Artificial Limb and Polio Centre (ALPC) in Gaza city in the Gaza strip with conflict-related traumatic extremity amputations. Patients were eligible if they had one or more amputations sustained during a military incursion in Gaza during 2006-16 and had an available patient record. Each patient completed a self-reporting questionnaire of the time and mechanism of injury, subsequent surgeries, comorbidities, and their socioeconomic status, and we collected each patient's medical history, recorded the anatomical location of their amputation or amputations, and interviewed each patient to obtain a detailed description of the incursion or incursions that led to their amputation injury. We classified the severity of amputations and number of subsequent surgeries on ordinal scales and then we determined the associations between these outcomes and the mechanism of explosive weapon delivery (drone strike vs other) using ordinal logistical regression. FINDINGS: We collected data on 254 patients from APLC who had sustained an amputation injury. Of these patients, 234 (92%) were male and 43 (17%) were aged 18 years or younger at the time of injury. The age of participants was representative of the Gaza population, with a median age at inclusion was 28 years (IQR 23-33), and the median age at the time of injury was 23 years (IQR 20-29). 136 (54%) amputation injuries were caused by explosive weapons delivered by drone strikes, with explosives delivered by tanks being the next most common source of amputation injury (28 [11%]). Adjusted for age and sex, drone-delivered weapons caused significantly more severe injuries than explosives delivered by other mechanisms (eg, military jet airplanes, helicopters, tank shelling, and naval artillery; odds ratio [OR] 2·50, 95% CI 1·52-4·11; p=0·0003). Compared with all other types of weapons, the patients whose injuries were caused by drone strikes needed significantly more subsequent surgical operations to treat their amputation injuries than those injured by other weapons (OR 1·93, 1·19-3·14; p=0·008). INTERPRETATION: Drone strikes were the most commonly reported cause of amputation injury in our study population and were associated with more severe injuries and more additional surgeries than injuries caused by other explosive weapons. Limitations of our study include the self-reported nature of the mechanism of injury and number of subsequent surgeries and selection bias from not incorporating amputation injuries from individuals who died immediately or due to complications. The increasing use of drones needs to be addressed, rather than passively accepted, by the international community. This study fills a gap in our knowledge of the civilian consequences of modern warfare and we believe it is also relevant to the growing populations that are being exposed to drone warfare and for health-care personnel treating these people. FUNDING: None.

Failure of Indomethacin and Radiation to Prevent Blast-induced Heterotopic Ossification in a Sprague-Dawley Rat Model.

BACKGROUND: Although use of nonsteroidal antiinflammatory drugs and low-dose irradiation has demonstrated efficacy in preventing heterotopic ossification (HO) after THA and surgical treatment of acetabular fractures, these modalities have not been assessed after traumatic blast amputations where HO is a common complication that can arise in the residual limb. QUESTIONS/PURPOSES: The purpose of this study was to investigate the effectiveness of indomethacin and irradiation in preventing HO induced by high-energy blast trauma in a rat model. METHODS: Thirty-six Sprague-Dawley rats underwent hind limb blast amputation with a submerged explosive under water followed by irrigation and primary wound closure. One group (n = 12) received oral indomethacin for 10 days starting on postoperative Day 1. Another group (n = 12) received a single dose of 8 Gy irradiation to the residual limb on postoperative Day 3. A control group (n = 12) did not receive either. Wound healing and clinical course were monitored in all animals until euthanasia at 24 weeks. Serial radiographs were taken immediately postoperatively, at 10 days, and every 4 weeks thereafter to monitor the time course of ectopic bone formation until euthanasia. Five independent graders evaluated the 24-week radiographs to quantitatively assess severity and qualitatively assess the pattern of HO using a modified Potter scale from 0 to 3. Assessment of grading reproducibility yielded a Fleiss statistic of 0.41 and 0.37 for severity and type, respectively. By extrapolation from human clinical trials, a minimum clinically important difference in HO severity was empirically determined to be two full grades or progression of absolute grade to the most severe. RESULTS: We found no differences in mean HO severity scores among the three study groups (indomethacin 0.90 ± 0.46 [95% confidence interval {CI}, 0.60-1.19]; radiation 1.34 ± 0.59 [95% CI, 0.95-1.74]; control 0.95 ± 0.55 [95% CI, 0.60-1.30]; p = 0.100). For qualitative HO type scores, the radiation group had a higher HO type than both indomethacin and controls, but indomethacin was no different than controls (indomethacin 1.08 ± 0.66 [95% CI, 0.67-1.50]; radiation 1.89 ± 0.76 [95% CI, 1.38-2.40]; control 1.10 ± 0.62 [95% CI, 0.70-1.50]; p = 0.013). The lower bound of the 95% CI on mean severity in the indomethacin group and the upper bound of the radiation group barely spanned a full grade and involved only numeric grades < 2, suggesting that even if a small difference in severity could be detected, it would be less than our a priori-defined minimum clinically important difference and any differences that might be present are unlikely to be clinically meaningful. CONCLUSIONS: This work unexpectedly demonstrated that, compared with controls, indomethacin and irradiation provide no effective prophylaxis against HO in the residual limb after high-energy blast amputation in a rat model. Such an observation is contrary to the civilian experience and may be potentially explained by either a different pathogenesis for blast-induced HO or a stimulus that overwhelms conventional regimens used to prevent HO in the civilian population. CLINICAL RELEVANCE: HO in the residual limb after high-energy traumatic blast amputation will likely require novel approaches for prevention and management.