The recovery of a patient with an amputation often comes with many challenges and complications, including low back pain (LBP), heterotopic ossification (HO), and limb pain. Low back pain has been reported in 43%–82% of individuals with amputations, with higher incidence in those with traumatic amputations.1–4 The prevalence and severity of LBP also tend to be greater in individuals with a transfemoral amputation relative to more distal levels of amputation.1,5 Previous literature has suggested that LBP in persons with amputations may be more bothersome than phantom pain or residual limb pain,5 often leading to higher levels of disability.6
There have been some attempts to identify faulty mechanics that contribute to the development of LBP in individuals with amputation. Morgenroth et al.7 found that individuals with unilateral transfemoral amputations who self-reported LBP displayed greater transverse (rotational) plane excursion in the lumbar spine during ambulation than did individuals with transfemoral amputations without LBP. Friel et al.6 found that persons with amputations and complaints of LBP displayed greater iliopsoas muscle length and less back extensor endurance compared with persons with amputations without complaints of LBP. Hendershot et al.8,9 have identified altered trunk neuromuscular behaviors in patients with unilateral amputation, affecting dynamic trunk stiffness and postural stability. Others have demonstrated increased variability in stride-to-stride trunk-pelvis gait kinematics in individuals with LBP.10,11 However, there have yet to be directional cause-effect relationships established between altered trunk-pelvis biomechanics and concomitant LBP. Furthermore, additional factors make LBP in people with amputations a multifactorial problem, including prosthetic malalignment, poor socket fit, level of amputation, poor posture, increased lumbar lordosis, leg length discrepancy, and deconditioning.4
There is an abundance of treatment options for those with LBP, ranging from medications including nonsteroidal anti-inflammatory drugs and muscle relaxants, exercise therapy, movement reeducation, core stability, and spinal manipulation.12–14 For patients presenting with nonradicular pain with suspected origin in the sacroiliac and facet joints, corticosteroid injections may have benefit as both a diagnostic and therapeutic tool, followed by radiofrequency ablation if pain cannot be altered.15 Little is known about the influence of prosthetic design and alignment on LBP for patients with bilateral transfemoral amputations.
Heterotopic ossification, the formation of excess bone in nonosseous tissues, has been a secondary complication of the residual limb reported in 80% of persons with amputations as a result of blast injuries.16 This abnormal bone growth may cause pain, difficulty with prosthetic socket fit, and skin breakdown. Symptomatic HO can be treated nonoperatively with rest, physical therapy, and/or prosthetic modifications, or it can be surgically resected.16–18 Traditionally, patients with transfemoral amputations are fit with quadrilateral sockets or ischial containment sockets. With an ischial containment socket design, the ischial tuberosity takes on most of vertical support, unloading the soft tissue of the residual limb.19 More recently, the design of subischial sockets, with trimlines that do not encroach the pelvis, have been investigated and found to allow for more hip extension range of motion during gait, along with improved speed and agility during functional tasks and increased patient satisfaction.20
Optimizing patient function and quality of life is the overarching goal of rehabilitation. Individuals with bilateral amputations struggle to become functional upright ambulators (<19%)21,22; therefore, wheelchairs often become one's primary mobility, impacting functional independence and quality of life.21–25 Predictors of successful ambulation for individuals with amputations include younger age and longer stay in rehabilitation units, whereas residual limb complications such as open wounds and infections tend to lead to less successful walking with a prosthetic device.26
The purpose of this case report is to describe a multidisciplinary approach to treat LBP in an individual with bilateral transfemoral amputations. The multidisciplinary team included physical medicine and rehabilitation physicians, orthopedic surgeons, plastic surgeons, physical therapists, certified prosthetists, and biomechanical engineers.
MATERIALS AND METHODS
The patient was a 27-year-old man, an active-duty US Navy service member, who was 72 in tall and weighed 125 lb (without prosthetic devices). He was injured by an improvised explosive device in February 2013. The patient experienced bilateral traumatic transtibial amputations, which were later revised to transfemoral amputations due to infection and extensive tissue damage. Other injuries included soft tissue injury to the right thigh and buttock, right testicular injury, and multiple left hand fractures. The patient was treated by a multidisciplinary team in the Comprehensive Combat and Complex Casualty Care (C5) Department27 at the Naval Medical Center San Diego (NMCSD). For a complete timeline of the patient's care, refer to Figure 1. In May 2013, the patient was initially fit with short prostheses (“stubbies”) with bilateral ischial containment and seal-in suction, without functional knee or ankle joints. After 3 weeks of training in stubbies, the patient transitioned to long prostheses with microprocessor (X3) knee (Ottobock, Duderstadt, Germany) components and energy-storage and return (ESAR) prosthetic feet. During his first year of care, he was treated by a physical therapy clinician on average 7.8 times per month. Physical therapy focused on therapeutic exercise, functional activities, gait training, self-care management, and pain management (soft tissue mobilization, scar desensitization, and ultrasound). In addition, the patient underwent a full-body instrumented gait analysis as part of routine rehabilitative care in September 2013 (collection 1). At 1 year postinjury, the patient had developed significant HO of his right residual limb and neuromas in the bilateral lower limbs (Figure 2). The abnormal bone growth (HO) caused residual limb pain and difficulty with prosthetic socket fit. The patient also continued to report LBP, and in February 2014, he underwent a local anesthetic and steroid injection at the sacroiliac joint, which resulted in improvement of right sacroiliac joint pain. Surgical revision of the patient's right residual limb was elected at this time. Starting in March 2014, tissue expanders were placed in his right thigh and gradually increased in size in efforts to improve soft tissue coverage of the residual limb. In June 2014 (1 year 4 months after injury), the patient underwent extensive surgical revision to excise the HO and bilateral residual limb neuromas and to remove tissue expanders. Postoperative healing was slowed due to a wound infection.
In November 2014 (6 months after the revision), the patient was refitted for prosthetic sockets. The patient began gait training in short prostheses without knee or ankle joints and similar ischial containment design to sockets previously described. The patient continued to report LBP and was then treated with oral medications, including naproxen, Valium, and Dilaudid, and subsequent corticosteroid injections at the right sacroiliac joint (November 2014). The patient reported a pain reduction from 7 of 10 to 0 of 10 after injections. The injections had a noted benefit for a limited period, which served as a diagnostic tool to localize pain origin. In an effort to find a more long-lasting solution to LBP, a multidisciplinary team strategized a treatment plan aimed at reducing lumbar lordosis and anterior pelvic tilt, which would in turn decrease overloading at sacroiliac joints and ultimately improve pain and function. Within 9 months of revision, in March 2015, the patient transitioned to standard-length prostheses but with a revised socket design. The revised sockets were double walled, with subischial containment, which provided less intrusion on pelvic alignment. It was understood that this socket design would provide less stability. The microprocessor (X3) knee components and ESAR feet were kept consistent with his first pair of long prostheses. Physical therapy frequency decreased to 2.5 visits, on average, per month during his second year of rehabilitation and later decreased to an average of 1.5 visits per month in his third year of rehabilitation. Physical therapy continued to focus on core strengthening, functional activities, gait training, and community reintegration. In addition, in the new subischial socket design concomitant to physical rehabilitation, the patient's gait was analyzed longitudinally over the subsequent 4 months, in April 2015 (collection 2), June 2015 (collection 3), and August 2015 (collection 4) (Figure 3). The socket shape and alignment were the same at collections 2 and 3. Between collections 3 and 4, proximal trim lines were lowered bilaterally and the left socket was posteriorly translated relative to the knee. Any changes in alignment were minimal and based on the patient's transition to the subischial socket design. Footwear was selected by the patient based on the activities he planned for that day and aesthetics. The patient selected shoes with a 0–3/8-in heel height, which was accommodated for using heel wedges.
Three outcome measures were utilized in this case: Oswestry Disability Index (ODI), Short Musculoskeletal Function Assessment Questionnaire (SMFA), and the Patient Reported Outcomes Measurement Information System (PROMIS)–Global Health (GH). The ODI is a validated measure of disability associated with LBP. Scores on the ODI can range from 0% to 100%, where a higher score indicates a higher degree of functional limitation and disability related to LBP.28 The SMFA is a 46-item questionnaire that aims to assess functional status and how bothered one is from functional problems. This scale has been found to have excellent reliability, content, and construct validity.29 A decrease in score is representative of improvement.29 The PROMIS-GH Scale is a 10-item survey that measures health-related quality of life with respect to physical and mental domains; an increase in score is indicative of improvement. This scale has been found to have good construct validity.30 Self-report measures were not recorded before HO resection. Responses on the ODI, SMFA, and PROMIS-GH were obtained at each of collections 2, 3, and 4.
In each of the three-dimensional gait analyses performed throughout treatment, the following protocol was applied. A 12-camera motion capture system (Motion Analysis Corporation, Santa Rosa, CA, USA) was used to collect three-dimensional kinematic data. Marker trajectories were sampled at 120 Hz and low pass filtered at 6 Hz. Two Canon V1 video cameras (Digital West Imaging, San Diego, CA, USA) were used to collect reference videos. The patient was outfitted with a six-degree-of-freedom marker set (27 tracking, eight calibrations). Pelvis motion was tracked with bilateral markers on the anterior superior and posterior superior iliac spine. Trunk motion was tracked with C7 spinous process, bilateral manubrium, and bilateral acromion. Lower-limb motion was tracked with rigid clusters of four markers attached to the lateral thigh and lateral shank using layered Coban, as well as with three markers on the foot (posterior calcaneus, lateral base of the fifth metatarsal, and second metatarsal head). Joint axes of the knee and ankle were estimated using single markers placed medially and laterally on the prosthetic mechanical knee axis and on the approximate prosthetic foot proximal end during a static calibration trial with patient standing in a T-pose (arms abducted to 90°, elbows in full extension, and forearms pronated) with a comfortable base of support. Static alignment measurements were calculated from this standing T-pose. The patient was then asked to walk at a self-selected velocity across a 10-m walkway multiple times until a minimum of six strides (footstrike to footstrike) per left/right leg were collected.
Kinematic data were first quality-checked in Cortex (Motion Analysis Corp., Santa Rosa, CA, USA) and then exported to Visual3D (C-Motion, Inc., Germantown, MD, USA). Kinematic analysis was limited to the trunk and pelvis, using an X-Y-Z (sagittal, frontal, transverse) Euler rotation sequence to measure rotation of trunk and pelvis relative to the laboratory, and of the trunk relative to the pelvis. Values during static standing were extracted as the average over one second. In each gait trial, joint angles were normalized relative to standing values, and joint excursion was calculated as maximum minus minimum over the gait cycle. Intercycle excursion values were reduced to intercycle average and standard deviation. Spatiotemporal parameters were also calculated using Visual3D and included walking velocity, cadence, step width, step length, and single limb stance time.
The patient's ODI improved from moderate (26%) to minimal (6%) disability between collection 2 and collection 3. A score of minimal disability (10%) was maintained through collection 4 (Table 1). The patient demonstrated improvements in all subscores of the SMFA and PROMIS-GH from collection 2 to collection 3, maintained through collection 4 (Table 1). The patient's report of LBP reduced from 4 of 10 pain to no pain within 2 months of ambulating with the subischial containment sockets. Reduction in pain, without the need for pain management medications or corticosteroid injections, has demonstrated long-lasting effects through June 2016.
For standing alignment, the greatest magnitude of change in joint angle was in the sagittal plane. The angle of the trunk relative to the pelvis progressively decreased over time in the amount of extension from 27.8°, 26.7°, 20.4°, to 18.8° from collections 1 through 4. This decrease is attributed to pelvic repositioning, as the trunk remained vertical throughout all collections (0.1°–3.5°) (Table 2, Figure 3).
During gait, excursion of the trunk relative to the pelvis decreased by 4.6° in the sagittal plane, 6.4° in the frontal plane, and 4.0° in the transverse plane from collection 1 to collection 4. Excursion of the trunk and pelvis (relative to the lab) decreased in all planes with the exception of frontal plane trunk motion (increased by 1.4°) from collection 1 to 4. The overall change in the trunk and pelvis excursions exceeds the previously reported minimal detectable change,31 indicating clinically relevant magnitudes of change. Intercycle variability was low (<3°) within each collection in all planes, with the most variability in the transverse plane (Table 3).
Spatiotemporal variables during gait remained relatively unchanged over the patient's course of rehabilitation regardless of time, socket design, or LBP (Table 2). Self-selected gait velocity ranged from 1.02 to 1.06 m/second, cadence ranged from 102 to106 steps/minute, and stride length ranged from 114 to 124 cm. Step width narrowed after the HO resection and with the revised socket design, from 19.9 cm at collection 1 to 14.3 cm at collection 4. Bilateral single limb stance time did not change across time; fairly equal time was spent in single limb stance between limbs. Step length was persistently asymmetric, with the right step longer than the left step throughout rehabilitation (Table 4).
A multidisciplinary approach is crucial in providing optimal care through the rehabilitation of a patient with an amputation.32,33 In C5 at NMCSD, wounded service members have access to a multidisciplinary team with expertise in amputation rehabilitation.27 This particular case demonstrated the positive outcomes that can result from this approach.
Various medical professionals provided treatment, along with valuable insight, that played a role in the success of this case. Extensive orthopedic and plastic surgery were necessary to reshape the patient's residual limbs. Having a pain-free, cylindrical residual limb is ideal for prosthetic socket fit. The use of a subischial containment socket places increased stress on upper-leg soft tissue structures compared to traditional designs. Therefore, residual limb shape, pliability, weight-bearing tolerance, and minimization of soft tissue deficits (reduction in grafted skin tissue) were important aspects to consider before transitioning this patient to a subischial containment socket. The primary intention of this treatment approach was to improve static and dynamic spinopelvic alignment, in efforts to reduce LBP believed to have a sacroiliac joint etiology as indicated by diagnostic and therapeutic effect of corticosteroid injections.
Three-dimensional motion capture provided objective outcomes during gait and standing posture that demonstrated treatment success for sagittal plane correction. This patient demonstrated a 9.5° decrease in anterior pelvic tilt (pelvis relative to lab) during standing, greater than a suggested minimal detectable threshold for clinically significant intersession change.31 The improvement in spinopelvic alignment likely contributed to improvement in pain, with additional contributions from improved core stability as a result of physical therapy treatment. The patient also exhibited decreases in trunk-pelvis relative excursions, suggesting improved neuromuscular control of core musculature. Decreased relative transverse plane rotational excursion with the corresponding decrease in reported LBP as observed for this patient agrees with previous research comparing mechanics of individuals with unilateral transfemoral amputations with LBP to those without LBP.7
Improvements in alignment were even more meaningful based on the patient's subjective report of improvement in LBP and functioning. Alignment changes were most likely heavily influenced by the subischial socket design. These alignment changes, along with the HO and neuroma excisions and physical therapy treatment, all contributed to the patient's improvement in reports of LBP.
The success of this treatment approach with socket modification was also largely due in part to the age, body composition, length and state of residual limbs, and level of fitness of the patient. Caution is advised on use of this socket design for older, less fit patients with amputations due to a decrease in stability. Without a strong core, balance and stability will be further compromised. The results from this case study are difficult to generalize at this point in time. Future research should experiment with this minimal socket design on patients of different ages and with varying body composition.
A subischial socket design utilized by a patient with bilateral transfemoral amputations paired with comprehensive physical therapy rehabilitation and gait training improved trunk-pelvis mechanics during standing and ambulation, which in turn led to a decrease in LBP and improved quality of life. Expertise from various medical professionals on a multidisciplinary team was integral in this treatment approach and achievement of functional outcomes. Results from this case study are difficult to generalize at this point. Future research should examine the effects of subischial socket design on bilateral transfemoral patients across a greater cohort of subjects.
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