The influence of limb alignment and transfemoral amputation technique on muscle capacity during gait.

Many factors influence successful outcomes following transfemoral amputation. One factor is surgical technique. In this study, the influence of limb alignment and surgical technique on a muscle's capacity to generate force was examined using musculoskeletal modeling. Non-amputee and transfemoral amputee models were analyzed while hip adduction, femur length, and reattached muscle wrap position, tension and stabilization technique were systematically varied. With muscle tension preserved, wrap position and femur length had little influence on muscle capacity. However, limb alignment, muscle tension and stabilization technique notably influenced muscle capacity. Overall, myodesis stabilization provided greater muscle balance and function than myoplasty stabilization.

Falls in a Young Active Amputee Population: A Frequent Cause of Rehospitalization?

Falls occur in up to 50% of amputees within a single year of their operation and up to 40% of these falls result in injury. However, there is a lack of data evaluating falls in a young, active amputee population despite an estimated 58% of persons living with an amputation being under the age of 65. The authors evaluated an amputee population (n = 393) with a mean age of 25.53 years. Overall incidence, prevalence, fall characteristics, and risk factors were calculated for falls resulting in rehospitalization. An incidence of 1.92 per 1,000 person years with a prevalence of 2.04% was found with 87.5% occurring within the first 6 months following definitive amputation. Of the patients rehospitalized, 75% required at least 1 surgical procedure. Infectious complications had the most significant morbidity requiring a mean of 5 operative procedures. Those that delayed evaluation (mean = 13 days) vs. those that presented 0 to 1 day from a fall were significantly more at risk of an infectious complication (p = 0.03). This study is the first to report such a relationship, and emphasizes the need for at-risk patients to seek early medical attention as this may minimize the risk of infection and obviate the need for surgical intervention.

Reoperation after combat-related major lower extremity amputations.

OBJECTIVE: Complication rates leading to reoperation after trauma-related amputations remain ill defined in the literature. We sought to identify and quantify the indications for reoperation in our combat-injured patients. DESIGN: Retrospective review of a consecutive series of patients. SETTING: Tertiary Military Medical Center. PATIENTS/PARTICIPANTS: Combat-wounded personnel sustaining 300 major lower extremity amputations from Operations Iraqi and Enduring Freedom from 2005 to 2009. INTERVENTION: We performed a retrospective analysis of injury and treatment-related data, complications, and revision of amputation data. Prerevision and postrevision outcome measures were identified for all patients. MAIN OUTCOME MEASUREMENTS: The primary outcome measure was the reoperation on an amputation after a previous definitive closure. Secondary outcome measures included ambulatory status, prosthesis use, medication use, and return to duty status. RESULTS: At a mean follow-up of 23 months (interquartile range: 16-32), 156 limbs required reoperation leading to a 53% overall reoperation rate. Ninety-one limbs had 1 indication for reoperation, whereas 65 limbs had more than 1 indication for reoperation. There were a total of 261 distinct indications for reoperation leading to a total of 465 additional surgical procedures. Repeat surgery was performed semiurgently for postoperative wound infection (27%) and sterile wound dehiscence/wound breakdown (4%). Revision amputation surgery was also performed electively for persistently symptomatic residual limbs due to the following indications: symptomatic heterotopic ossification (24%), neuromas (11%), scar revision (8%), and myodesis failure (6%). Transtibial amputations were more likely than transfemoral amputations to be revised due to symptomatic neuromata (P = 0.004; odds ratio [OR] = 3.7; 95% confidence interval [95% CI] = 1.45-9.22). Knee disarticulations were less likely to require reoperation when compared with all other amputation levels (P = 0.0002; OR = 7.6; 95% CI = 2.2-21.4). CONCLUSIONS: In our patient population, reoperation to address urgent surgical complications was consistent with previous reports on trauma-related amputations. Additionally, persistently symptomatic residual limbs were common and reoperation to address the pathology was associated with an improvement in ambulatory status and led to a decreased dependence on pain medications.

Risk factors for and results of late or delayed amputation following combat-related extremity injuries.

We studied patients with combat-related injuries that required delayed amputation at least 4 months after the initial injury due to dysfunction, persistent pain, and patient desires. Late amputations were performed 22 times in 22 patients (21 men, 1 woman) since 2003. Fourteen patients underwent transtibial amputation, 5 transfemoral amputations, 1 knee disarticulation, and 2 transradial amputations. The primary indications for late amputation were neurologic dysfunction in 6 patients, persistent or recurrent infection in 6, neurogenic pain in 3, non-neurogenic pain in 5, and a globally poor functional result in 2. Sixteen of 22 patients reported multiple indications for electing to undergo amputation, with an average of 2.1 specific indications per patient. At final clinical follow-up an average of 13 months after amputation, all patients reported subjectively improved function and reported that they would undergo amputation again under similar circumstances. When medically and functionally practicable, every effort is given to limb salvage following severe combat-related extremity injuries. There is no single risk factor that increases the likelihood of delayed amputation, but the combination of complex pain symptoms with neurologic dysfunction appears to increase the risk, particularly if the initial insult is a severe hindfoot injury or distal tibia fracture. With appropriately selected and counseled patients, elective late amputation results in a high degree of patient satisfaction and subjectively improved function.

Imaging of synovial chondromatosis with radiologic-pathologic correlation.

Primary synovial chondromatosis represents an uncommon benign neoplastic process with hyaline cartilage nodules in the subsynovial tissue of a joint, tendon sheath, or bursa. The nodules may enlarge and detach from the synovium. The knee, followed by the hip, in male adults are the most commonly involved sites and patient population. The pathologic appearance may simulate chondrosarcoma because of significant histologic atypia, and radiologic correlation to localize the process as synovially based is vital for correct diagnosis. Radiologic findings are frequently pathognomonic. Radiographs reveal multiple intraarticular calcifications (70%-95% of cases) of similar size and shape, distributed throughout the joint, with typical "ring-and-arc" chondroid mineralization. Extrinsic erosion of bone is seen in 20%-50% of cases. Computed tomography (CT) optimally depicts the calcified intraarticular fragments and extrinsic bone erosion. Magnetic resonance (MR) imaging findings are more variable, depending on the degree of mineralization, although the most common pattern (77% of cases) reveals low to intermediate signal intensity with T1-weighting and very high signal intensity with T2-weighting with hypointense calcifications. These signal intensity characteristics on MR images and low attenuation of the nonmineralized regions on CT scans reflect the high water content of the cartilaginous lesions. CT and MR imaging depict the extent of the synovial disease (particularly surrounding soft-tissue involvement) and lobular growth. Secondary synovial chondromatosis can be distinguished from primary disease both radiologically (underlying articular disease and fewer chondral bodies of variable size and shape) and pathologically (concentric rings of growth). Treatment of primary disease is surgical synovectomy with removal of chondral fragments; recurrence rates range from 3% to 23%. Malignant transformation to chondrosarcoma is unusual (5% of cases) and, although difficult to distinguish from benign disease, is suggested by multiple recurrences and marrow invasion. Recognizing the appearances of primary synovial chondromatosis, which reflect their underlying pathologic characteristics, improves radiologic assessment and is important to optimize patient management.

Heterotopic ossification following traumatic and combat-related amputations. Prevalence, risk factors, and preliminary results of excision.

BACKGROUND: Although infrequently reported in amputees previously, heterotopic ossification has proven to be a common and problematic clinical entity in our recent experience in the treatment of traumatic and combat-related amputations related to Operation Enduring Freedom and Operation Iraqi Freedom. The purpose of the present study was to report the prevalence of and risk factors for heterotopic ossification following trauma-related amputation as well as the preliminary results of operative excision. METHODS: We identified 330 patients with a total of 373 traumatic and combat-related amputations who had been managed at our centers between September 11, 2001 and November 30, 2005. We reviewed the medical records and radiographs of 187 patients with 213 amputations who had adequate radiographic follow-up. Additional analysis was performed for twenty-four patients with twenty-five limbs that required excision of symptomatic lesions. The mechanism and zone of injury, amputation level, timing of excision, use of prophylaxis against recurrence, and other confounding variables were examined. Outcomes were assessed by determining clinical and radiographic recurrence rates, perioperative complications, preoperative and follow-up pain medication requirements, and the ability to be fit with a functional prosthesis. RESULTS: Heterotopic ossification was present in 134 (63%) of 213 residual limbs, with twenty-five lesions requiring excision. A final amputation level within the zone of injury was a risk factor for both the development and the grade of heterotopic ossification (p < 0.05). A blast mechanism was predictive of occurrence (p < 0.05) but did not correlate with grade. All patients who had been managed with excision were tolerating the prosthetic limb at an average of twelve months of follow-up. Twenty-three limbs demonstrated no evidence of recurrence, and two limbs had development of clinically asymptomatic, radiographically minimal recurrences. Six patients experienced wound-related complications that required reoperation, and two patients required subsequent minor revision surgery. There was a significant decrease in the use of pain medication following surgery (p < 0.05). CONCLUSIONS: Heterotopic ossification following trauma-related amputation is more common than the literature would suggest, particularly following amputations that are performed within the initial zone of injury and those that are due to blast injuries. Many patients are asymptomatic or can be successfully managed with modification of the prosthesis. For patients with refractory symptoms, surgical excision is associated with low recurrence rates and decreased medication requirements, with acceptable complication rates.

From the archives of the AFIP: Imaging of synovial sarcoma with radiologic-pathologic correlation.

Synovial sarcoma is the fourth most common type of soft-tissue sarcoma, accounting for 2.5%-10.5% of all primary soft-tissue malignancies worldwide. Synovial sarcoma most often affects the extremities (80%-95% of cases), particularly the knee in the popliteal fossa, of adolescents and young adults (15-40 years of age). Despite its name, the lesion does not commonly arise in an intraarticular location but usually occurs near joints. Histologic subtypes include monophasic, biphasic, and poorly differentiated; the cytogenetic aberration of the t(X;18) translocation is highly specific for synovial sarcoma. Although radiographic features of these tumors are not pathognomonic, findings of a soft-tissue mass, particularly if calcified (30%), near but not in a joint of a young patient, are very suggestive of the diagnosis. Cross-sectional imaging features are vital for staging tumor extent and planning surgical resection; they also frequently reveal suggestive appearances of multilobulation and marked heterogeneity (creating the "triple sign") with hemorrhage, fluid levels, and septa (creating the "bowl of grapes" sign). Two features associated with synovial sarcoma that may lead to an initial mistaken diagnosis of a benign indolent process are slow growth (average time to diagnosis, 2-4 years) and small size (< 5 cm at initial presentation); in addition, these lesions may demonstrate well-defined margins and homogeneous appearance on cross-sectional images. Synovial sarcoma is an intermediate- to high-grade lesion, and, despite initial aggressive wide surgical resection, local recurrence and metastatic disease are common and prognosis is guarded. Understanding and recognizing the spectrum of appearances of synovial sarcoma, which reflect the underlying pathologic characteristics, improve radiologic assessment and are important for optimal patient management.

Differentiating clinical and radiographic features of enchondroma and secondary chondrosarcoma in the foot.

BACKGROUND: Enchondroma is the most common benign tumor of the bones of the foot. Chondrosarcoma in this area is relatively rare with malignant transformation from enchondroma occurring rarely. In contrast to similar tumors in the appendicular skeleton, it is difficult to distinguish between these two tumors when they occur in the foot. METHODS: We reviewed the medical records and radiographs of all patients with enchondroma and chondrosarcoma arising from enchondroma (secondary chondrosarcoma) from the radiologic archives at the Armed Forces Institute of Pathology (AFIP) and identified those patients with tumors involving the bones of the foot. There were 755 patients with enchondroma of which 34 (4.8%) involved the foot; there were 340 patients with secondary chondrosarcoma and 14 (4.1%) involved the foot. We compared clinical and radiographic features of both these lesions. We also compared interobserver differences not only for diagnosis but also for the presence of scalloping, fracture, cortical destruction, and mineralized matrix. RESULTS: Size and location were statistically significant variables differentiating the two tumors (p = 0.03). Enchondromas had a mean size of 2.7 cm(2). Lesions that occurred in the hindfoot and midfoot were more likely to be malignant compared to those in the forefoot. In comparing interobserver reliability, most disagreement occurred regarding the presence or absence of matrix with the examiners concurring only 51% of the time. With regard to diagnosis, the examiners' accuracy was 71% and 80%. Their accuracy increased only to 83% when they agreed. CONCLUSION: Our findings suggest that it is difficult to differentiate enchondroma from secondary chondrosarcoma in the foot. Concern for malignant change is warranted for cartilage bone tumors of the foot if they exceed 5 cm(2), or if they arise in the midfoot or hindfoot. In these cases, we recommend either biopsy or close clinical followup.

The "floating ankle": a pattern of violent injury. Treatment with thin-pin external fixation.

The "floating ankle" is an underappreciated pattern of injury that results from violent trauma and/or blast injuries in military personnel. It is characterized by an intact ankle mortise with a distal tibia fracture and an ipsilateral foot fracture, creating instability around the ankle. This pattern of injury may be the result of the military boot, which both protects the foot from immediate amputation or further injury and renders the distal tibia susceptible to fracture at the boot top. Four patients with open floating ankle injuries were treated with thin-pin circular fixation with good results. Two patients required bone transport for segmental loss. All patients are ambulatory without assistance or bracing. Thin-pin external fixation is a reasonable approach to this complex injury pattern, especially in the presence of marked soft tissue compromise with or without segmental bone loss.