Jason T. Long

Long-Term Outcome Evaluation in Young Adults Following Clubfoot Surgical Release

Background The aim of this study was to evaluate the long-term outcome of a comprehensive surgical release for congenital talipes equinovarus (CTEV). Methods Gait, strength, segmental foot motion, and outcomes questionnaire data were collected on 24 adults (21.8±2.3 y) who were surgically treated for CTEV as infants. These data were statistically compared with of 48-age group matched controls (23.2±2.4 y). Results The clubfoot group was functional in activities of daily living, although most patients did experience foot pain after a day of typical activities, such as walking, standing, using stairs and doing exercise. Lower extremity gait kinematics was similar to the control group. There were differences in segmental foot motion with the hindfoot in a more plantarflexed position relative to the tibia and the forefoot dorsiflexed, and adducted relative to the hindfoot. Ankle plantarflexion and inversion strength and range of motion was reduced in the clubfoot group in association with an increase in hip power generation during the preswing and initial swing phases of the gait cycle. Conclusions Surgical correction of CTEV was successful in providing a functional plantigrade foot as the patients reached adulthood. However, limitations included foot pain, limited foot range of motion, and weakness. Level of Evidence Level III.

Quantitative motion analysis in patients with hallux rigidus before and after cheilectomy.

The purpose of this study was to quantify changes in temporal‐spatial parameters and multisegmental foot/ankle kinematics in a group of patients with hallux rigidus following cheilectomy. Three‐dimensional motion analysis was conducted using a 15‐camera Vicon Motion Analysis System on a population of 19 patients who underwent cheilectomy for hallux rigidus. Data were analyzed using the four‐segment Milwaukee Foot Model. Preoperative and postoperative tests were compared using paired parametric methods. Results showed significant improvements in walking speed, cadence, stride length, and stance/swing ratio from preoperative to postoperative state. Altered hallux and forefoot positions preoperatively showed shifts towards normal after cheilectomy. Although clinical improvements in pain and passive range of motion were statistically significant, similar improvements in range of motion were not demonstrated during ambulatory testing. The results of this study provide insight into ambulatory improvements following cheilectomy, and suggest further study of the rehabilitation process to improve the recovery of functional range of motion.

Surgical reconstruction of posterior tibial tendon dysfunction: prospective comparison of flexor digitorum longus substitution combined with lateral column lengthening or medial displacement calcaneal osteotomy.

Posterior tibial tendon dysfunction (PTTD) may require surgical intervention when nonoperative measures fail. Different methods of bony reconstruction may supplement tendon substitution. This study compares two types of bony procedures used to reinforce reconstruction of the posterior tibial tendon-the lateral column lengthening (LCL), and the medial displacement calcaneal osteotomy (MDCO). Twenty patients with PTTD were evaluated before and after scheduled reconstruction comprised of either flexor digitorum longus (FDL) substitution combined with MDCO (MDCO group, 14 patients) or FDL substitution with LCL fusion or osteotomy (LCL group, 6 patients). Foot/ankle kinematics and temporal-spatial parameters were analyzed using the Milwaukee Foot Model, and results were compared to a previously evaluated normal population of 25 patients. Post-operatively, both patient groups demonstrated significantly improved stride length, cadence and walking speed, as well as improved hindfoot and forefoot position in the sagittal plane. The LCL group also demonstrated greater heel inversion. All post-operative subjects revealed significant improvement in the talo-MT1 angle in the A/P and lateral planes, calcaneal pitch and medial cuneiform-MT5 height. Surgical reconstruction of PTTD with either the LCL or MDCO shows comparable improvements in gait parameters, with better heel inversion seen with the LCL, but improved 1st ray plantarflexion and varus with the MDCO. Both procedures demonstrated comparable improvements in radiographic measurements.

Repeatability and sources of variability in multi-center assessment of segmental foot kinematics in normal adults

Multi-site application of biomechanical models can be a powerful tool as quantitative methods are employed to improve clinical care and to assess larger populations for research purposes. However, the use of such models depends on adequate validation to assure reliability in inter-site measures. We assessed repeatability and sources of variability associated with the assessment of segmental foot kinematics using the Milwaukee Foot Model during multiple testing sessions at two sites. Six healthy ambulators were instrumented and tested during comfortable ambulation; data were analyzed with variance components analysis using a mixed effects linear model. Results indicated that the largest source of variability was inter-subject; measurement error associated with Site and Session fell below 3.5 degrees in over 80% of position measurements and below 2.5 degrees in over 80% of ROM measurements. These findings support the continued use of the segmental foot model at multiple sites for clinical and research purposes.

Motion of the Multisegmental Foot in Hallux Valgus

Background: Hallux valgus is a common condition characterized by lateral deviation of the large toe and medial deviation of the first metatarsal. While some gait analyses of patients with hallux valgus have been performed using plantar pressures, very little is known about the kinematics of gait in this population. The purpose of this study was to evaluate triplanar kinematics in patients with hallux valgus using a multisegmental foot model. Materials and Methods: A 15-camera Vicon Motion Analysis System was used to evaluate the gait of 38 feet in 33 patients with mild to severe hallux valgus. The Milwaukee foot model was used to characterize dynamic foot and ankle kinematics and temporal-spatial parameters. Values were compared with normal subjects. Outcomes were evaluated using the SF-36 assessment tool. Results: Patients with hallux valgus showed significantly decreased velocity and stride length and prolonged stance. Significant alterations in gait kinematics were observed in various planes in all segments (hallux, forefoot, hindfoot, and tibia) of the foot and ankle, particularly in the ranges of motion of the hallux and the forefoot. Conclusion: The results demonstrate significantly altered kinematic and temporal-spatial parameters reflective of reduced ambulatory function in patients with hallux valgus. As reports describing multisegmental foot and ankle kinematics in this population are limited, this study is valuable in characterizing gait in patients with hallux valgus. Clinical Relevance: A better understanding of altered gait dynamics of the multisegmental foot in patients with hallux valgus provides valuable insight on how distal pathology affects proximal segments.

Multisegmental Foot and Ankle Motion Analysis After Hallux Valgus Surgery

Background: Gait changes in patients with hallux valgus, including altered kinematic and temporal-spatial parameters, have been documented in the literature. Although operative treatment can yield favorable clinical and radiographic results, restoration of normal gait in this population remains unclear. Segmental kinematic changes within the foot and ankle during ambulation after operative correction of hallux valgus have not been reported. The aim of this study was to analyze changes in multisegmental foot and ankle kinematics in patients who underwent operative correction of hallux valgus. Methods: A 15-camera Vicon Motion Analysis System was used to evaluate 24 feet in 19 patients with hallux valgus preoperatively and postoperatively. The Milwaukee Foot Model was used to characterize segmental kinematics and temporal-spatial parameters (TSPs). Preoperative and postoperative kinematics and TSPs were compared using paired nonparametric methods; comparisons with normative data were performed using unpaired nonparametric methods. Outcomes were evaluated using the SF-36 assessment tool. Results: Preoperatively, patients with hallux valgus showed significantly altered temporal-spatial and kinematic parameters. Postoperatively, kinematic analysis demonstrated restoration of hallux position to normal. Hallux valgus angles and intermetatarsal angles were significantly improved, and outcomes showed a significant increase in performance of physical activities. Temporal-spatial parameters and kinematics in the more proximal segments were not significantly changed postoperatively. Conclusion: Postoperative results demonstrated significant improvement in foot geometry and hallux kinematics in the coronal and transverse planes. However, the analysis did not identify restoration of proximal kinematics. Clinical Relevance: Further investigation is necessary to explore possible causes/clinical relevance and appropriate treatment interventions for the persistently altered kinematics.

Combined sagittal and coronal plane postural stability model.

We present a preliminary study of combined anterior posterior (AP) and medial lateral (ML) sway assuming a classic inverted pendulum with included subtalar movement. Based on a feedback control posture model in the sagittal plane, we have investigated parameters needed to model ML sway components. Center of pressure (COP) data was collected from a population of 8 normal adults (age 18 to 30 years) using a dual AMTI force plate system. Fourteen different sway metrics were calculated. The collected data was successfully compared to numerous simulations of the model where model parameters were varied and the goal was to reproduce both AP and ML components

Gait abnormality following amputation in diabetic patients.

Amputations of the lower extremity may result from several etiologic factors. Most amputations performed in the United States result from a dysvascular limb. A majority of the population with vascular impairment comprises people with diabetes. These individuals frequently have comorbidities that may also affect the ultimate outcome of amputation. Loss of protective sensation, propensity toward infection, and visual and balance impairment all create additional issues with postamputation gait in the population with diabetes. Amputations about the foot and ankle affect gait and energy consumption. More gait disturbances tend to be seen as amputation level becomes more proximal; however, loss of the metatarsophalangeal joints has a profound effect, regardless of the proximal level of amputation. Soft tissue balance is key to maximizing gait, particularly prevention of equinus and equinovarus deformity from unopposed plantarflexors. Orthotic, prosthetic, and shoe modifications can help minimize gait abnormalities; however alterations of ground reaction force and center of pressure may still remain.

A multisegmental foot model with bone-based referencing: Sensitivity to radiographic input parameters

We present a new kinematic model measuring the three-dimensional orientation of multiple segments of the foot and ankle. The model defines neutral alignments based on the alignments of the underlying bony segments, and indexes the orientation of skin-mounted markers to the bony anatomy using measures from weightbearing x-rays. The sensitivity of the model to these radiographic input parameters was analyzed using data from walking trials. Kinematic output in each plane was found to be most sensitive to perturbations of radiographic measurements in that same plane; however, perturbations in the coronal and transverse planes demonstrated significant carry-over into other planes. The analysis highlights the importance of accurately accounting for the underlying anatomy in measuring intersegmental kinematics.

Application of a bi-planar postural stability model in children with cerebral palsy

This study presents initial results from a bi-planar model used to investigate the neurological factors affecting balance deficits in children with diplegic cerebral palsy (CP). The model uses an inverted pendulum to describe sway in both the anteroposterior (AP) and mediolateral (ML) planes. The study presents Center of Pressure (COP) data from 17 children diagnosed with spastic diplegic CP using two standard AMTI force plates. Sway metrics in the time and frequency domains in the AP and ML planes were calculated and compared to simulations produced by the model. The proposed bi-planar model successfully reproduced sway signals acquired from experimental (clinical) data.