Design and optimization of a new integrated hip and knee prosthesis structure.

BACKGROUND: Conventional hip disarticulation prostheses (HDPs) are passive devices with separate joint structures, limiting amputees' ability to control and resulting in abnormal gait patterns. This study introduces a new HDP integrating the hip and knee joints for amputees' natural gait. METHODS: The new HDP restores the physiological rotation center of the hip with a remote center of motion (RCM) structure, and simulates the knee motion with a four-bar structure. Nonlinear programming was employed to optimize the hip-knee joint structure. A hybrid multi-objective drive structure with a series-parallel connection was also designed to ensure motion synergy between the hip and knee joints. Finally, a prototype of the prosthesis was tested using the HDP test system. RESULTS: The optimization results demonstrate that the new HDP accurately restores the rotation center of the femur in amputees, with the knee's instantaneous center of rotation (ICR) trajectory closely resembling that of the human knee (Pearson correlation coefficient is 0.999). The study shows that the new HDP achieves a motion reproduction accuracy of over 95% for the human hip joint at walking speeds above 1.5 km/h, 38% higher than conventional prosthesis. Similarly, at the same walking speed, the new HDP replicates the motion of the human knee at 82.89%, surpassing conventional prosthesis by 57.85%. CONCLUSIONS: The new HDP restores symmetry and replicates synergistic movement in amputees' lower limbs, exhibiting superior movement characteristics compared to conventional prostheses. This innovative HDP has the potential to enhance the quality of life for amputees.

Targeted Muscle Reinnervation to Reduce Postoperative Pain in Patients Undergoing Hindquarter Resections.

BACKGROUND/AIM: Pre-emptive targeted muscle reinnervation (TMR) at the time of amputation results in less phantom limb pain (PLP) compared with untreated amputee controls. There is limited literature describing the technique in patients undergoing hindquarter amputation despite up to 90% of these patients reporting PLP and 50% presenting with painful neuroma. The purpose of the current study was to describe the motor nerves accessible through a primary hind-quarter amputation to be used for TMR and review pain outcomes in clinical case correlates of patients with TMR. PATIENTS AND METHODS: Six limbs were obtained from three fresh adult cadavers and proximal sensory and motor nerves were dissected. A review of patients undergoing hindquarter amputation with TMR was conducted. RESULTS: Transfers for the sciatic, femoral, and obturator nerves were identified in cadavers. In reviews of patients, they were taking narcotic and neuro-leptic pain medication for a mean of 23 days and 168 days. At most recent follow-up, no patient reported debilitating phantom pain nor pain associated with neuromas. CONCLUSION: Given the positive preliminary results in our study group as well as the accessible neuroanatomy, pre-emptive TMR should be considered at the time of surgery to limit PLP and dependence on pain medications.

Biomechanical gait analysis for a hip disarticulation prosthesis: power source for the swing phase of a hip disarticulation prosthetic limb.

[Purpose] This study aimed to clarify the power source for the swing phase of a hip disarticulation prosthetic limb using biomechanical gait analysis. [Participants and Methods] In this cross-sectional study, six participants who underwent hip disarticulation and seven healthy adults were recruited. Their gaits were assessed using the three-dimensional motion analysis and four force plates. [Results] From pre-swing to initial swing, the angle of the lumbar spine's angle changed by 9° from the flexion to extension positions. However, the power of the lumbar spine was <0.003 W/kg for the entire gait cycle. The peak value of joint moment and hip joint power on the unaffected side were 1 nm/kg and 0.7 W/kg, respectively. From pre-swing to initial swing, the prosthetic limb is pushed forward by extension of the hip joint on the intact side, while the spine returns to the flexion direction. [Conclusion] The hip extension force on the unaffected side was the main force responsible for swinging out the prosthesis, not the lumbar vertebrae's force.

Development of a Hip Joint Socket by Finite-Element-Based Analysis for Mechanical Assessment.

This article evaluates a hip joint socket design by finite element method (FEM). The study was based on the needs and characteristics of a patient with an oncological amputation; however, the solution and the presented method may be generalized for patients with similar conditions. The research aimed to solve a generalized problem, taking a typical case from the study area as a reference. Data were collected on the use of the current improving prosthesis-specifically in interaction with its socket-to obtain information on the new approach design: this step constituted the work's starting point, where the problems to be solved in conventional designs were revealed. Currently, the development of this type of support does not consider the functionality and comfort of the patient. Research has reported that 58% of patients with sockets have rejected their use, because they do not fit comfortably and functionally; therefore, patients' low acceptance or rejection of the use of the prosthesis socket has been documented. In this study, different designs were evaluated, based on the FEM as scientific support for the results obtained, for the development of a new ergonomic fit with a 60% increase in patient compliance, that had correct gait performance when correcting postures, improved fit-user interaction, and that presented an esthetic fit that met the usability factor. The validation of the results was carried out through the physical construction of the prototype. The research showed how the finite element method improved the design, analyzing the structural behavioral, and that it could reduce cost and time instead of generating several prototypes.

Retrospective analysis of mortality and quality of life after hip disarticulation or hemipelvectomy: a report on 15 patients.

BACKGROUND: Hip disarticulation and hemipelvectomy are defined as major ablative amputations of the lower limb. Due to the small number of patients, little is known about the outcome and follow-up. AIMS: We aimed to assess (1) reasons for performed major ablative surgeries such as hip disarticulation and hemipelvectomy in a German center for trauma and orthopedic surgery. (2) In addition, mortality and quality of life after hip disarticulation and hemipelvectomy as well as (3) patient and treatment characteristics should be investigated. METHODS: During a period of twelve years, 15 patients underwent hip disarticulation or hemipelvectomy. Mortality, EQ-5D-3L quality of life by EQ-5D-3L and time-trade-off (TTO), VAS, cause of disarticulation, length of hospital stays, revisions, comorbidities, Charlson comorbidity index (CCI), and ASA score were evaluated retrospective for all patients. RESULTS: The overall mortality rates were 26.7% at 30 days, 60.0% after one year and 66.7% after three years. The five surviving patients reported about moderate problems in the EQ-5D-3L. The average VAS score reached 45 (range 15-65). The mean TTO was 9.8 (range 6-12). Indications for amputation were infection (n = 7), tumor (n = 6), trauma (n = 1) and ischemia (n = 1). CONCLUSION: Hip disarticulation and hemipelvectomy are followed by a high postoperative mortality. Quality of life of the affected patients is impaired in long-term follow-up. Especially amputations performed due to infections show high mortality within one month after surgery despite average young age and low CCI. Surgeons should be aware of this devastating outcome and extraordinary vigilant for these vulnerable patient cohorts.

Current Predictors of Mortality in Veteran Patients Undergoing Major Lower Extremity Amputations: Risk Factors Have Not Changed and Mortality Remains High.

Major lower extremity amputation (LEA-above the ankle) carries a high rate of mortality. In the present study, we performed an institutional review of all patients submitting to LEAs at a Veteran Administration Hospital (between 2009 and 2021) accompanied with a review of the literature.For the past 12 years, 1042 LEAs were performed in 603 patients at our hospital. The 30-day, 1-year, and 5-year mortalities were 8.5%, 28.9%, and 53.0%, respectively. Age, hypoalbuminemia, and Clavien-Dindo Class were independent predictors of mortality in all the time intervals in the analysis. Cardiac disease was not an independent predictor of mortality. In 39 studies reviewed, the average 30-day, 1-year, and 5-year mortality was 14%, 36%, and 56%, respectively. There was no difference in mortality in multiple studies analyzed. No significant temporal variation was identified between 1950 and 2000 vs. 2001 and 2021. Predictors of mortality were not substantially different from our institutional experience.The mortality rate for LEAs remains constant over time. Increasing age and hypoalbuminemia are strong predictors of short- and long-term mortality.

A hip disarticulation prostheses test system to simulate gait for prostheses evaluation.

BACKGROUND: The limited number of hip prostheses users makes it less feasible to conduct amputee tests for prosthesis development in the clinic, which restricts the development efficiency of the intelligent prostheses. OBJECTIVE: This study proposes a hip disarticulation prostheses test system (HDPTS) to supplement the amputee tests for hip disarticulation prosthesis (HDP) evaluation, which would potentially facilitate the prosthesis evaluation safety and development efficiency. METHODS: The hip trajectory of an individual with normal gait was acquired and reproduced by calculating the corresponding movement joint angle of a manipulator. Then, an HDP was fit on an amputee and on the HDPTS respectively to obtain the hip and knee joint angles of the HDP during walking. Comparing the root mean square error (RMSE) of the expected and planned trajectory, the joint angles between the amputee test and HDPTS test, to verify the feasibility and accuracy of the HDPTS for prosthesis evaluation. RESULTS: The RMSE between the expected and planned trajectory value was less than 1.20 mm (< 0.19%). The RMSE of the joint angles between the amputee test and HDPTS test were 2.18∘ (1.8%) and 3.13∘ (5.92%) for hip and knee joint respectively. CONCLUSION: The HDPTS was found accurate in hip trajectory reproduction and feasible in gait simulation for the prosthesis evaluation, which could potentially supplement the amputee test for prosthesis design thus improving prosthesis test safety and development efficiency.

Delayed femoral vein ligation reduces operative time and blood loss during hip disarticulation in patients with extremity tumors.

This study aimed to evaluate the effects of delayed femoral vein ligation on the clinical outcomes of hip disarticulation. We retrospectively reviewed 20 patients with extremity tumors (10 bone tumors and 10 soft tissue sarcomas [STS]) who underwent hip disarticulation. Patients treated for hip disarticulation with synchronous femoral vein ligation (n = 10, regular surgery group) and hip disarticulation with delayed femoral vein ligation (n = 10, delayed ligation group), respectively, were enrolled in this study. The operative time and blood loss were used to evaluate the clinical outcomes. The delayed ligation group had significantly lower operative times than the regular surgery group (P < 0.05). Total, hidden, and intraoperative blood loss were all significantly lower in the delayed ligation group than in the regular surgery group (P < 0.05). However, there were no significant differences in postoperative blood loss. In conclusion, delayed femoral vein ligation could significantly reduce the operative time, hidden blood loss, and intraoperative blood loss in patients undergoing hip disarticulation.

Hip Disarticulation in Wound Care: A Case Series.

Background: Hip disarticulation (HD) is a radical lower extremity amputation performed by carefully transecting all muscles and nerves surrounding the hip joint and separating the leg at the joint capsule. It is considered a last resort to be used as a life-preserving measure under emergent circumstances due to high rates of morbidity and mortality. Methods: This case series presents 4 patients who underwent HD. The procedure was performed due to various indications including necrotizing fasciitis, gangrene, stump necrosis from previous above-the-knee amputation, and septic joint secondary to chronic osteomyelitis, 3 of which were planned and 1 was emergent. Results: The procedure was performed successfully in all 4 patients. Furthermore, all patients were eventually discharged to home or to a long-term care facility for wound care or rehabilitation. Conclusions: Overall, HD should be reserved as a life-saving treatment for various indications including infections that fail other modalities, limb ischemia, trauma, and malignancy. Ideally, this procedure would be planned and performed on proper candidates; however, HD should still be a consideration in the emergent setting regardless of most optimal patients due to its life-saving potential.

Design of a Bio-Inspired Gait Phase Decoder Based on Temporal Convolution Network Architecture With Contralateral Surface Electromyography Toward Hip Prosthesis Control.

Inter-leg coordination is of great importance to guarantee the safety of the prostheses wearers, especially for the subjects at high amputation levels. The mainstream of current controllers for lower-limb prostheses is based on the next motion state estimation by the past motion signals at the prosthetic side, which lacks immediate responses and increases falling risks. A bio-inspired gait pattern generation architecture was proposed to provide a possible solution to the bilateral coordination issue. The artificial movement pattern generator (MPG) based on the temporal convolution network, fusing with the motion intention decoded from the surface electromyography (sEMG) measured at the impaired leg and the motion status from the kinematic modality of the prosthetic leg, can predict four sub gait phases. Experiment results suggested that the gait phase decoder exhibited a relatively high intra-subject consistency in the gait phase inference, adapted to various walking speeds with mean decoding accuracy ranging from 89.27 to 91.16% across subjects, and achieved an accuracy of 90.30% in estimating the gait phase of the prosthetic leg in the hip disarticulation amputee at the self-selected pace. With the proof of concept and the offline experiment results, the proposed architecture improves the walking coordination with prostheses for the amputees at hip level amputation.

Evaluating hip disarticulation outcomes in a 51-patient series.

Background: Hip disarticulations are proximal lower extremity amputations with high postoperative complication and mortality rates. The purpose of the study was to evaluate hip disarticulation outcomes at our institution. Targeted Muscle Reinnervation (TMR) is an effective surgical technique shown to reduce pain in amputees. A secondary goal of the study was to evaluate the impact of implementing TMR on this patient population. Methods: A retrospective review was performed for patients who underwent hip disarticulation with and without TMR between 2009 and 2020. Information on one-year mortality, thirty-day complication rates, operation times, surgical charges, and pain scores was collected. Results: Fifty-one patients underwent hip disarticulation, eight of which had TMR performed at the time of their hip disarticulation. The one-year mortality rate was 37% with 30-day infection, readmission, reoperation, and rates of 37%, 39%, and 27% respectively. The thirty-day major complication rate was 47% overall but not statistically significantly different between groups. There were no differences between groups with regard to 30-day readmission, reoperation, and infection rates. Conclusions: Our results represent one of the largest series of hip disarticulation outcomes. Performing TMR at the time of hip disarticulation did not negatively affect outcomes and may be a beneficial adjunct to improve pain. Further research is warranted.

Necrotizing Fasciitis After Total Hip Arthroplasty: A Rare Case Presentation.

BACKGROUND: Necrotizing fasciitis (NF) is a life-threatening disease. Arthroplasty patients with underlying or preexisting conditions and chronic medication use are prone to infection. The current report aimed to present a 53 years old female patient who developed necrotizing fasciitis one month after total hip arthroplasty. CASE PRESENTATION: On the postoperative 15th day, she had wound discharge. She was given oral anti- biotherapy. At postoperative 1 month, her complaints increased. At emergency service, she experienced extreme pain in her lower extremity with pseudoparalysis, and a hip X-ray revealed gas images. She used prednisolone for 10 years and insulin for 15 years because of pemphigus vulgaris and diabetes mellitus. Clinical and laboratory findings led us to the diagnosis of necrotizing fasciitis. Despite aggressive treatment, including debridement, prosthesis removal, and antibiotherapy, unfortunately, the patient died 13 days after admission. CONCLUSION: Patients with an immune suppressive condition, long-term corticosteroid use, or multiple underlying diseases should be closely monitored after total hip arthroplasty surgery to avoid such a devastating complication.

Gait Analysis of Hip Disarticulation Amputees Based on Kinematic Parameters and Plantar Pressure Measurement / 医用生物力学

Objective To analyze the gait characteristics of hip disarticulation amputees, and analyze the reasons for their differences from normal gait, so as to assist clinical diagnosis and evaluation. Methods Through the portable human motion capture device and plantar pressure analysis system, the kinematics and plantar pressure information of 5 hip amputees were collected and compared with 15 healthy volunteers in control group. Gait differences between the amputees and normal subjects and between the affected leg side and the healthy leg side of the amputees were compared. Results The proportion of double-support period for hip amuptees was higher than that of normal gait. Step length, step time, loading response period, mid support period, pre-swing period, proportion of the swing period for the affected leg side and healthy leg side of hip amputees showed significant differences with those of control group. The relative symmetry index of the gait for hip amputees was 0.60±0.05. Compared with the affected leg side, the support period of the healthy leg side was extended, the step length was shortened, the ground reaction force was greater than that of the affected leg side, and the center of pressure trajectory shifted to the affected leg side. Conclusions The gait of hip amputees is significantly different from that of normal people. Hip amputees have weak walking ability, poor gait symmetry, and they lack of continuity in the body’s center of gravity. The results provide experimental basis and theoretical analysis for the design of mechanical structure and control system of novel hip prosthesis.

[Design and simulation of dynamic hip prosthesis based on remote motion center mechanism].

The rotation center of traditional hip disarticulation prosthesis is often placed in the front and lower part of the socket, which is asymmetric with the rotation center of the healthy hip joint, resulting in poor symmetry between the prosthesis movement and the healthy lower limb movement. Besides, most of the prosthesis are passive joints, which need to rely on the amputee's compensatory hip lifting movement to realize the prosthesis movement, and the same walking movement needs to consume 2-3 times of energy compared with normal people. This paper presents a dynamic hip disarticulation prosthesis (HDPs) based on remote center of mechanism (RCM). Using the double parallelogram design method, taking the minimum size of the mechanism as the objective, the genetic algorithm was used to optimize the size, and the rotation center of the prosthesis was symmetrical with the rotation center of the healthy lower limb. By analyzing the relationship between the torque and angle of hip joint in the process of human walking, the control system mirrored the motion parameters of the lower on the healthy side, and used the parallel drive system to provide assistance for the prosthesis. Based on the established virtual prototype simulation platform of solid works and Adams, the motion simulation of hip disarticulation prosthesis was carried out and the change curve was obtained. Through quantitative comparison with healthy lower limb and traditional prosthesis, the scientificity of the design scheme was analyzed. The results show that the design can achieve the desired effect, and the design scheme is feasible.

Regaining Gait Using an Early Postoperative Hip Prosthesis: A Case Report of an Elderly Woman.

BACKGROUND: Hip prostheses are generally avoided in elderly patients because of cognitive decline and/or reduced muscle strength. The present report describes the case of an elderly woman who regained gait using a prosthesis prescribed during the early postoperative phase following hip disarticulation. CASE: A 78-year-old woman suffered from a pathological fracture caused by liposarcoma of the left thigh. Before hospitalization, the patient was fully independent in her activities of daily living, including gait. The right and left handgrip strengths were 12.9 and 14.2 kg, respectively, and the patient had no signs of cognitive decline. Radical treatment involving hip disarticulation was scheduled. Before surgery, the possibility of fitting a hip prothesis that would allow the patient to walk was discussed, to which she consented. On postoperative day 23, the patient was fitted with a hip prosthesis and began gait training. On day 31, she was able to walk using a fixed walker and, eventually, using a crutch. DISCUSSION: The present case demonstrated the successful reacquisition of gait using a hip prothesis prescribed during the early postoperative phase after amputation, suggesting that the applicability of hip prostheses may be widely considered even for elderly patients.

Soft tissue reconstruction after pelvic amputation: The efficacy and reliability of free fillet flap reconstruction.

BACKGROUND: The majority of hindquarter amputation defects can be reconstructed with local anterior or posterior thigh flaps. Less than 5% of soft tissue defects require free flap reconstruction after tumour resection. Lower extremity fillet flap is described for reconstructing such defects, but the majority of publications are case reports or short single institutional series. There is a lack of data regarding the oncological outcomes of this highly selected patient group. METHODS: Three tertiary sarcoma units treated twelve patients with hindquarter amputation or hip disarticulation for oncological indications with a free flap reconstruction of the soft tissue defect. RESULTS: The median age of patients was 60 (range 12-76) years. Bone resection was carried out through the SI-joint in six patients and through the sacrum in five patients, with one patient undergoing hip disarticulation. Nine patients had R0 resection margin and three had R1 resection. The median surgical time and flap ischaemia time was 420 (249-650) and 89 (64-210) min, respectively. Median hospital and ICU stay was 18 (10-42) and 3 (1-8) days, respectively. Median blood loss was 2400 (950-10000) ml. There were three returns to theatre due to vascular compromise, with one total flap loss due to arterial thrombosis. Overall survival was 58% (95%CI 28-91%) both at 1-year and at 3-years. DISCUSSION: Carefully selected patients requiring hindquarter amputation with extensive soft tissue defect necessitating free flap reconstruction can be reconstructed with a lower extremity free fillet flap with low rate of local wound complications. Survival of these patients is similar to that in patients requiring less extensive resection.

Design and optimization of a hip disarticulation prosthesis using the remote center of motion mechanism.

BACKGROUND: Hip disarticulation prostheses (HDPs) are not routinely seen in clinical practice, and traditional hip prostheses rotate around an axis at the front side of the pelvic socket. OBJECTIVE: This study proposes a mechanism to restore the rotation center to the acetabulum of the amputated side and uses comparative experiments with traditional HDP to verify the validity of the novel design. METHODS: A double parallelogram design of HDP based on a remote center of motion (RCM) mechanism was presented in this paper. Optimization was achieved by a genetic algorithm with the maximal integral size and minimal driving force of the mechanism. RESULTS: The prototype was developed by final optimal results and tested by a hip disarticulated amputee. Testing results revealed that the RCM-HDP improved the range of motion of the hip prosthesis by 78%. The maximal flexion of the assorted prosthetic knee was closer to the sound side than a traditional HDP by 15%. CONCLUSION: The proposed RCM-HDP promoted the kinematic performance and symmetry of the hip prosthesis compared to the traditional design.

Design and simulation of dynamic hip prosthesis based on remote motion center mechanism / 生物医学工程学杂志

The rotation center of traditional hip disarticulation prosthesis is often placed in the front and lower part of the socket, which is asymmetric with the rotation center of the healthy hip joint, resulting in poor symmetry between the prosthesis movement and the healthy lower limb movement. Besides, most of the prosthesis are passive joints, which need to rely on the amputee's compensatory hip lifting movement to realize the prosthesis movement, and the same walking movement needs to consume 2-3 times of energy compared with normal people. This paper presents a dynamic hip disarticulation prosthesis (HDPs) based on remote center of mechanism (RCM). Using the double parallelogram design method, taking the minimum size of the mechanism as the objective, the genetic algorithm was used to optimize the size, and the rotation center of the prosthesis was symmetrical with the rotation center of the healthy lower limb. By analyzing the relationship between the torque and angle of hip joint in the process of human walking, the control system mirrored the motion parameters of the lower on the healthy side, and used the parallel drive system to provide assistance for the prosthesis. Based on the established virtual prototype simulation platform of solid works and Adams, the motion simulation of hip disarticulation prosthesis was carried out and the change curve was obtained. Through quantitative comparison with healthy lower limb and traditional prosthesis, the scientificity of the design scheme was analyzed. The results show that the design can achieve the desired effect, and the design scheme is feasible.

Static Finite Element Analysis on Hip Disarticulation Prosthesis Socket-Residual Limb in Stance Phase / 医用生物力学

Objective To study mechanical properties of the interface between hip residual limb and hip socket during the stance phase by using the finite element analysis (FEA) method, so as to provide the theoretical basis for structure optimization and design of hip socket, as well as the research basis for comfort evaluation of hip socket. Methods According to CT scan images of the patient’s residual limb, the model of bone, soft tissues and socket was reconstructed by reverse modeling. The distribution of normal stress and shear stress on the interface between hip residual limb and hip socket was analyzed and a pressure acquisition module system was designed to verify the stress distribution condition. Results The interfacial stress between hip residual limb and hip socket was mainly distributed in the waist and the bottom of the residual limb, and the interfacial stress was more evenly distributed in the rest of the residual limb. The results of finite element calculation were in good agreement with the system measurement results of pressure acquisition module. Conclusions In order to improve force transfer and safety and comfort of the hip socket, it is necessary to fully consider stress condition of the waist and bottom of the residual limb, as well as the coordination degree between residual limb and hip socket.

Targeted muscle reinnervation following external hemipelvectomy or hip disarticulation: An anatomic description of technique and clinical case correlates.

BACKGROUND: Targeted muscle reinnervation (TMR) has been shown to decrease or prevent neuropathic pain, including phantom and residual limb pain, after extremity amputation. Currently, a paucity of data and lack of anatomical description exists regarding TMR in the setting of hemipelvectomy and/or hip disarticulations. We elaborate on the technique of TMR, illustrated through cadaveric and clinical correlates. METHODS: Cadaveric dissections of multiple transpelvic exposures were performed. The major mixed motor and sensory nerve branches were identified, dissected, and tagged. Amputated peripheral nerves were transferred to identified, labeled target motor nerves via direct end-to-end nerve coaptations per traditional TMR technique. A retrospective review was completed by our multi-institutional teams to include examples of clinical correlates for TMR performed in the setting of hemipelvectomies and hip disarticulations. RESULTS: A total of 12 TMR hemipelvectomy/hip disarticulation cases were performed over a 2 to 3-year period (2018-2020). Of these 12 cases, 9 were oncologic in nature, 2 were secondary to traumatic injury, and 1 was a failed limb salvage in the setting of chronic refractory osteomyelitis of the femoral shaft. CONCLUSIONS: This manuscript outlines the technical considerations for TMR in the setting of hemipelvectomy and hip disarticulation with supporting clinical case correlates.