Ankle biomechanics

Relationship Between the Flexion Torque of the First Metatarsophalangeal Joint and Intrinsic Foot Muscles Depends on the Ankle Joint Position

Background

Clinicians and researchers are beginning to pay attention to the importance of the intrinsic foot muscles (IFMs). Among IFMs, the abductor hallucis (AbH) is associated with foot disorders. However, so far no method for assessing the strength of the AbH has been established. In addition, previous studies have shown increased IFM activity in the plantarflexed position of the ankle. Therefore, this study tests the hypothesis that a correlation will be found between the cross-sectional area (CSA) of the AbH and the flexion torque and that the first metatarsophalangeal (MTP) joint would be stronger in the plantarflexed (PF) position of the ankle joint than in the neutral (N) position.

Methods

Eight male and 8 female patients (16 lower limbs) were included in this study to measure the CSA of IFM and the extrinsic foot muscles of the lower leg. Furthermore, the flexion torque of the first MTP joint was measured using a handheld dynamometer at the N and PF positions of the ankle joint. Correlation analysis was performed to examine the relationship between the CSA of each muscle and the flexion torque of the first MTP joint in the N and PF positions.

Results

In the N position, a correlation was found between the flexion torque of the first MTP joint and the CSA of the AbH (r = 0.818), flexor hallucis brevis (r = 0.730), and flexor hallucis longus (r = 0.726). In the PF position, a correlation was found between the flexion torque of the first MTP joint and the CSA of the AbH (r = 0.863) and flexor hallucis brevis (r = 0.680). (P < .05).

Conclusion

Overall, this study suggested that by measuring flexion torque of the first MTP joint in the PF position, AbH strength can be estimated without using any expensive equipment.

Level of Evidence

Level V, mechanism-baced reasoning.

Soft tissue coverage of the ankle: An algorithm for appropriate flap selection and the experiences of a newly established Major Trauma Network

INTRODUCTION

Replication of the thin and pliable native skin around the ankle remains a challenge for plastic surgeons treating soft tissue defects in this region. Flap reconstruction constitutes the mainstay of management of such injuries. Subsequent management often entails revisional debulking surgery to permit normal footwear and an acceptable aesthetic outcome. In light of limited elective operating capacity throughout the covid-19 pandemic, we adopted an algorithm to inform reconstruction in such injuries and limit the need for revisional surgeries. This study presents this algorithm, which considers patient age, functional status, co-morbidities, body habitus and defect location.

METHODS

Retrospective analysis of a prospectively maintained database of all patients undergoing lower limb soft tissue reconstruction over 21 months was performed. All flap-based reconstructions of ankle defects were included; direct closures and skin grafts were excluded. All trauma patients were managed via a combined orthoplastic approach as per BOA-BAPRAS standards. All patients had Computed Tomography Angiography prior to their definitive reconstruction. Lower Extremity Functional Scale (LEFS) scores were analysed for patients with over 12 months of postoperative follow up, where available.

RESULTS

71 flaps were performed in 69 patients. Open ankle fracture was the most common cause (86%); other indications included osteomyelitis and surgical wound dehiscence. Mean age was 50 (13-87 years) with a higher proportion of males to females (ratio 1.25:1). There were 26 pedicled flaps (18 Medial Plantar Artery and 8 Peroneus Brevis) and 45 free flaps (22 Anterolateral thigh, 11 Superficial Circumflex Iliac Artery Perforator, 11 Gracilis and 1 Medial Sural Artery Perforator). Mean follow-up is 13.6 months. There were three flap failures, and four patients subsequently underwent delayed below knee amputation despite successful soft tissue healing. For the patients with a minimum of 12 months follow up, LEFS scores with an average of 51% were achieved (range 15-88%). Four patients have been listed for revisional/debulking surgery.

CONCLUSION

Although soft tissue defects around the ankle can be difficult to manage, with careful planning and addressing each patient individually, supported by an algorithmic approach, good functional and aesthetic outcomes can be achieved with low rates of secondary revision surgery.

Tibiotalar and Tibiotalocalcaneal Arthrodesis with Paragon28 SilverbackTM Plating System in Patients with Severe Ankle and Hindfoot Deformity

BACKGROUND AND OBJECTIVES

The treatment of end-stage ankle osteoarthritis (OA) and associated hindfoot deformities remains a major challenge for orthopedic surgeons. Numerous techniques and surgical approaches have been proposed for tibiotalar (TT) and tibiotalocalcaneal (TTC) arthrodesis, from arthroscopic to open, as well as numerous devices proposed for internal fixation (retrograde intramedullary nails, cannulated screws, and plating systems). The aim of this study was to retrospectively analyze the results, with at least 18 months of follow-up, with Silverback^TM TT/TTC Plating System Paragon28 in a group of 20 patients with severe OA and hindfoot deformities (mainly secondary post-traumatic OA).

MATERIALS AND METHODS

The demographic characteristics and past medical history of the patients were collected and analyzed to identify the cause of the pathology. The degree of OA and deformity were quantified based on foot and ankle weight-bearing radiography and CT examination. Pre- and post-operative clinical and functional scores (ROM, VAS, AOFAS, FFI, and SF-36) and radiographic parameters (anterior distal tibial angle, tibiotalar angle, coronal tibiotalar angle, and hindfoot alignment angle) were evaluated.

RESULTS

All of the patients showed clinical and radiographic fusion at an average of 14 weeks (range 12-48), with improvement in pain and functional scores, without major surgical complications and/or infections.

CONCLUSIONS

Despite the limitations of our study, the results with this new plating system showed good results in terms of bone consolidation, post-operative complications, and improvement of pain and quality of life in patients with severe OA and deformities of the ankle and hindfoot.

Current management of trimalleolar ankle fractures

A trimalleolar ankle fracture is considered unstable and treatment is generally performed operatively. Computed tomography is important for the operative planning by providing an elaborated view of the posterior malleolus.

Trimalleolar ankle fractures have a rising incidence in the last decade with up to 40 per 100,000 people per year. With a growing number of elderly patients, trimalleolar ankle injuries will become more relevant in the form of fragility fractures, posing a particular challenge for trauma surgeons.

In patients with osteoporotic trimalleolar ankle fractures and relevant concomitant conditions, further evidence is awaited to specify indications for open reduction and internal fixation or primary transfixation of the ankle joint.

In younger, more demanding patients, arthroscopic-assisted surgery might improve the outcome, but future research is required to identify patients who will benefit from assisted surgical care.

This review considers current scientific findings regarding all three malleoli to understand the complexity of trimalleolar ankle injuries and provide the reader with an overview of treatment strategies and research, as well as future perspectives.

Cite this article: EFORT Open Rev 2021;6:692-703. DOI: 10.1302/2058-5241.6.200138

Distribution of segmental foot kinematics in patients with degenerative joint disease of the ankle

Degenerative joint disease (DJD) of the ankle is a debilitating chronic disease associated with severe pain and dysfunction resulting in antalgic gait alteration. Little information is available about segmental foot and ankle motion distribution during gait in ankle osteoarthritis. The aim of the current study was to dynamically characterize segmental foot and ankle kinematics of patients with severe ankle arthrosis requiring total ankle replacement. This was a prospective study involving 36 (19 M, 17 F) adult patients with a clinical diagnosis of ankle arthrosis ("DJD" group) and 36 (23 M, 13 F) healthy subjects ("Control" group). Motion data were collected at 120 Hz using a 3-D motion camera system at self-selected speed along a 6-m walkway and processed using the Milwaukee Foot Model (MFM). The SF-36 Health Survey and Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale were administered to evaluate functional levels. Findings include decreases in walking speed, cadence, stride length and swing phase, and reduced outcomes scores (SF-36 and AOFAS). Multisegemental motion in patients with ankle DJD demonstrates significant changes in foot mechanics characterized by altered segment kinematics and significant reduction in dynamic ROM at the tibia, hindfoot, forefoot, and hallux when compared to controls. The results demonstrate decreased temporal-spatial parameters and low outcomes scores indicative of functional limitations. Statement of clinical significance: Altered segment kinematics and reduced overall range of motion demonstrate how a single joint pathology affects kinematic distribution in the other segments of the foot and ankle and alters patients' overall gait. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1739-1746, 2018.

Development of a Robotic Assembly for Analyzing the Instantaneous Axis of Rotation of the Foot Ankle Complex

Ankle instantaneous axis of rotation (IAR) measurements represent a more complete parameter for characterizing joint motion. However, few studies have implemented this measurement to study normal, injured, or pathological foot ankle biomechanics. A novel testing protocol was developed to simulate aspects of in vivo foot ankle mechanics during mid-stance gait in a human cadaveric specimen. A lower leg was mounted in a robotic testing platform with the tibia upright and foot flat on the baseplate. Axial tibia loads (ATLs) were controlled as a function of a vertical ground reaction force (vGRF) set at half body weight (356 N) and a 50% vGRF (178 N) Achilles tendon load. Two specimens were repetitively loaded over 10 degrees of dorsiflexion and 20 degrees of plantar flexion. Platform axes were controlled within 2 microns and 0.008 degrees resulting in ATL measurements within ±2 N of target conditions. Mean ATLs and IAR values were not significantly different between cycles of motion, but IAR values were significantly different between dorsiflexion and plantar flexion. A linear regression analysis showed no significant differences between slopes of plantar flexion paths. The customized robotic platform and advanced testing protocol produced repeatable and accurate measurements of the IAR, useful for assessing foot ankle biomechanics under different loading scenarios and foot conditions.

Total ankle arthroplasty in the rheumatoid patient

Total ankle replacement in the rheumatoid patient is a feasible and effective treatment for ankle arthritis. The benefits of ankle prosthesis are good pain relief, acceptable function, and patient satisfaction. It is a joint-sparing procedure for restoring functionality. All investigators of total ankle replacement feel that, as clinicians gain experience with the procedure and related products, difficulties and risks associated with the procedure will decline. Following an early history of failure and poor patient satisfaction, more recent results have shown promise.

Kinematic changes of the foot and ankle in patients with systemic rheumatoid arthritis and forefoot deformity

Minimal published data exist characterizing the effect of rheumatoid arthritis of the forefoot (RA) on multi-segmental gait kinematics. The purpose of this study was to examine specific changes in segmental foot motion in patients with RA as compared to persons without foot/ankle pathology. This was a cross-sectional, descriptive study consisting of 22 preoperative adult patients (29 feet) diagnosed with RA and 25 adult patients with no known foot pathology (Control). All RA patients were evaluated by the same orthopaedic surgeon. This group consisted of 20 women and 2 men with a mean age of 54 years (range, 17-76 years). The Control cohort consisted of 13 men and 12 women with a mean age of 41 years (range, 27-73 years). Foot and ankle motion data for the RA population were obtained using a 15-camera Vicon Motion Analysis System (Vicon Motion Systems, Inc., Lake Forest, CA). Anterior-posterior, lateral, and modified coronal radiographic views were obtained to relate marker position to underlying bony anatomy. Temporal and three-dimensional kinematic parameters were obtained via the 4-segment Milwaukee Foot Model. Quantitative comparisons of range of motion values during the seven phases of gait were made between RA and Control ankles using unpaired nonparametric methods. The RA group showed significant differences (p < 0.001) as compared to Controls with prolonged stance time, shortened stride length, increased cadence, and a walking speed that was 80% of Control. Overall, kinematic data in the RA cohort showed significant differences (p < 0.001) in motion for tibial, hindfoot, and forefoot motion as compared to Controls. The effect of RA on segmental foot motion is poorly understood. This study characterized the effect that RA has on motion about the foot and ankle during gait, providing insight into this pathology to improve quantitative assessment, treatment planning, and rehabilitative care.

Preoperative gait characterization of patients with ankle arthrosis

The purpose of this study was to evaluate the kinematic changes that occur about the foot and ankle during gait in patients with degenerative joint disease (DJD). By comparing a normal adult population with what was found in the DJD population we determined how the motion of theses groups differed, thereby characterizing how this pathology affects foot and ankle motion. A 15-camera Vicon Motion Analysis System was used in conjunction with weight bearing radiographs to obtain three-dimensional motion of the foot and ankle during ambulation. The study was comprised of 34 patients and 35 ankles diagnosed with DJD (19 men and 15 women) of the ankle and 25 patients with normal ankles (13 men and 12 women). Dynamic foot and ankle motion was analyzed using the four-segment Milwaukee Foot Model (MFM). The data from this model resulted in three-dimensional (3D) kinematic parameters in the sagittal, coronal, and transverse planes as well as spatial-temporal parameters. Patient health status was evaluated using the SF-36 Health Survey and American Orthopaedics Foot and Ankle Society (AOFAS) hindfoot scores. The DJD group showed significant differences (p<0.001) as compared to normals with prolonged stance time, shortened stride length, reduced cadence and a walking speed which was only 66.96% of normal. Overall, kinematic data in the DJD cohort showed significant differences (p<0.001) in all planes of motion for tibial, hindfoot and forefoot motion as compared to normals. The average preoperative AOFAS hindfoot score was 26. DJD of the ankle results in decreased range of motion during gait. This decreased range of motion may be related to several factors including bony deformity, muscle weakness, and attempts to decrease the pain associated with weight bearing. To date there has not been a study which describes the effect of this disease process on motion of the foot and ankle. These findings may prove to be useful in the pre-operative assessment of these patients.

Ankle fractures

Although ankle injuries are common, it is imperative for the treating physician to be able to identify the mechanism of injury and accurately restore the normal anatomy of the ankle joint. Attention must be given to restoring the normal alignment and length of the fibula because of its dominant role in controlling talar stability. The medial ankle must not be overlooked, with the role of the deltoid taken into consideration. With a thorough understanding of the anatomy, biomechanics, mechanism of injury, and fixation techniques, repair of the damaged ankle joint can lead to rewarding outcomes for the patient and physician.