Injuries observed in minimalist runners.

BACKGROUND: Minimalist runners have been shown to have a different gait pattern with lower impact forces than habitually shod runners. Running in minimalist footwear has been promoted as a means of reducing or eliminating running injuries by returning to a more natural gait. METHODS: Ten experienced runners, age 21 to 57 (mean, 43) years, were identified with injuries within 1 year of transition from traditional to minimalist running footwear. Patients were interviewed to determine their running history, injury history, transition to minimalist footwear, and their new injury including its treatment and recovery. RESULTS: Ten patients who ran with traditional footwear ran an average of 25.9 (range, 6 to 45) miles/week for an average of 18.9 (range, 1 to 40) years presented with injuries 2.8 (range 1 to 10) months after switching to minimalist footwear. Their injuries included eight metatarsal stress fractures, a calcaneal stress fracture, and a plantar fascia rupture. All patients had a successful recovery and returned to their previous level of running. CONCLUSION: Injuries including stress fractures and plantar fascia rupture have been observed in minimalist runners.

The use of flexor to extensor transfers for the correction of the flexible hammer toe deformity.

Flexor to extensor transfer is a useful means for the correction of a flexible hammer toe deformity. Although satisfaction rates have varied in the literature, this technique remains a useful tool in the surgeon's armamentarium to improve toe deformity, decrease pain, and aid in shoe wear.

Effect of post-traumatic tibiotalar osteoarthritis on kinematics of the ankle joint complex.

BACKGROUND: Knowledge of joint kinematics in the healthy and diseased joint may be useful if surgical techniques and joint replacement designs are to be improved. To date, little is known about the kinematics of the arthritic tibiotalar joint and its effect on the kinematics of the subtalar joint. MATERIALS AND METHODS: Kinematics of the ankle joint complex (AJC) were measured in six patients with unilateral post-traumatic tibiotalar osteoarthritis in simulated heel strike, midstance and toe off weight bearing positions using magnetic resonance and dual fluoroscopic imaging techniques. The kinematic data obtained was compared to a normal cohort from a previous study. RESULTS: From heel strike to midstance, the arthritic tibiotalar joint demonstrated 2.2 +/- 5.0 degrees of dorsiflexion while in the healthy controls the tibiotalar joint plantarflexed 9.1 +/- 5.3 degrees (p < 0.01). From midstance to toe off, the subtalar joint in the arthritic group dorsiflexed 3.3 +/- 4.1 degrees whereas in the control group the subtalar joint plantarflexed 8.5 +/- 2.9 degrees (p < 0.01). The subtalar joint in the arthritic group rotated externally 1.2 +/- 1.0 degrees and everted 3.3 +/- 6.1 degrees from midstance to toe off while in the control group 12.3 +/- 8.3 degrees of internal rotation and 10.7 +/- 3.8 degrees eversion (p < 0.01 and p < 0.01, respectively) was measured. CONCLUSION: The current study suggests that during the stance phase of gait, subtalar joint motion in the sagittal, coronal, and transverse rotational planes tends to occur in an opposite direction in subjects with tibiotalar osteoarthritis when compared to normal ankle controls. This effectively represents a breakdown in the normal motion coupling seen in healthy ankle joints. CLINICAL RELEVANCE: Knowledge of ankle kinematics of arthritic joints may be helpful when designing prostheses or in assessing the results of treatment interventions.

Function of anterior talofibular and calcaneofibular ligaments during in-vivo motion of the ankle joint complex.

BACKGROUND: Despite the numerous in-vitro studies on the mechanical properties and simulated injury mechanisms of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL), the in-vivo biomechanical behavior of these two ligaments has not yet been described. METHODS: Apparent length of the ATFL and CFL was measured in four ankles in healthy male subjects between 32 and 45 years of age (two left and two right) during a dorsiflexion-plantarflexion and supination-pronation arc of motion using a combined dual-orthogonal fluoroscopic and magnetic resonance imaging technique. RESULTS: The ATFL elongated from the neutral position at 16.3 +/- 3.0 mm to 20.8 +/- 2.7 mm at maximal plantarflexion and shortened significantly from the neutral position to 13.9 +/- 2.9 mm at maximal dorsiflexion (p = 0.01). The CFL shortened from the neutral position at 28.0 +/- 2.9 mm to 26.6 +/- 2.2 mm at maximal plantarflexion (p = 0.08) and elongated significantly from the neutral position to 29.9 +/- 3.0 mm at maximal dorsiflexion (p = 0.003). The ATFL elongated significantly from 14.8 +/- 2.5 mm at maximal pronation to 17.4 +/- 3.0 mm at maximal supination (p = 0.08). At the same time, the CFL shortened from 31.0 +/- 3.8 mm at maximal pronation to 26.9 +/- 3.6 mm at maximal supination (p = 0.02). CONCLUSION: The results showed that the ATFL elongates more during plantarflexion and supination whereas the CFL increases in length with dorsiflexion and pronation. Concurrently, these data also demonstrated the reciprocal function between the two ligaments. While one shortens, the other one elongates. The different elongation of the ATFL and CFL during the same motion arc suggests that under excessive loading conditions the ATFL might be more vulnerable in plantarflexion and supination while the CFL might be more susceptible to injury in dorsiflexion and pronation. Furthermore, in the case of surgical reconstruction the grafts used to reconstruct the two ligaments may need to be tensioned at different positions of the ankle in order to reproduce their natural in vivo function.

In vivo cartilage contact deformation of human ankle joints under full body weight.

Quantitative data on in vivo deformation of articular cartilage is important for understanding the articular joint function and the etiology of degenerative joint diseases such as osteoarthritis. This study experimentally determined the in vivo cartilage thickness distribution and articular cartilage contact strain distribution in human ankle joints under full body weight loading conditions using a combined dual fluoroscopic and magnetic resonance imaging technique. The average cartilage thickness with the joint non-weight bearing was found to be 1.43 mm +/- 0.15 mm and 1.42 mm +/- 0.18 mm in the distal tibial and proximal talar cartilage layers, respectively. During weight bearing on a single leg, the strain distribution data revealed that 42.4% +/- 15.7% of the contact area had contact strain higher than 15% in the ankle joint. Peak cartilage contact strain reached 34.5% +/- 7.3%. This quantitative data on in vivo human cartilage morphology and deformation demonstrated that the cartilage may undergo large deformations under the loading conditions experienced in human ankle joints during daily activities. The in vivo cartilage contact deformation can be used as displacement boundary conditions in three-dimensional (3D) finite element models of the joint to calculate in vivo 3D articular cartilage contact stress/strain distributions.

Six DOF in vivo kinematics of the ankle joint complex: Application of a combined dual-orthogonal fluoroscopic and magnetic resonance imaging technique.

Accurate knowledge of in vivo ankle joint complex (AJC) biomechanics is critical for understanding AJC disease states and for improvement of surgical treatments. This study investigated 6 degrees-of-freedom (DOF) in vivo kinematics of the human AJC using a combined dual-orthogonal fluoroscopic and magnetic resonance imaging (MRI) technique. Five healthy ankles of living subjects were studied during three in vivo activities of the foot, including maximum plantarflexion and dorsiflexion, maximum supination and pronation, and three weight-bearing positions in simulated stance phases of walking. A three-dimensional (3D) computer model of the AJC (including tibia, fibula, talus, and calcaneus) was constructed using 3D MR images of the foot. The in vivo AJC position at each selected position of the foot was captured using two orthogonally positioned fluoroscopes. In vivo AJC motion could then be reproduced by coupling the orthogonal images with the 3D AJC model in a virtual dual-orthogonal fluoroscopic system. From maximum dorsiflexion to plantarflexion, the arc of motion of the talocrural joint (47.5 +/- 2.2 degrees) was significantly larger than that of the subtalar joint (3.1 +/- 6.8 degrees). Both joints showed similar degrees of internal-external and inversion-eversion rotation. From maximum supination to pronation, all rotations and translations of the subtalar joint were significantly larger than those of the talocrural joint. From heel strike to midstance, the plantarflexion contribution from the talocrural joint (9.1 +/- 5.3 degrees) was significantly larger than that of the subtalar joint (-0.9 +/- 1.2 degrees). From midstance to toe off, internal rotation and inversion of the subtalar joint (12.3 +/- 8.3 degrees and -10.7 +/- 3.8 degrees, respectively) were significantly larger than those of the talocrural joint (-1.6 +/- 5.9 degrees and -1.7 +/- 2.7 degrees). Strong kinematic coupling between the talocrural and subtalar joints was observed during in vivo AJC activities. The contribution of the talocrural joint to active dorsi-plantarflexion was higher than that of the subtalar joint, whereas the contribution of the subtalar joint to active supination-pronation was higher than that of the talocrural joint. In addition, the talocrural joint demonstrated larger motion during the early part of stance phase while the subtalar joint contributes more motion during the later part of stance phase. The results add quantitative data to an in vivo database of normals that can be used in clinical diagnosis, treatment, and evaluation of the AJC after injuries.

Posterior tibial tendon insufficiency: which ligaments are involved?

BACKGROUND: The pathology manifested in posterior tibial tendon insufficiency (PTTI) is not limited to the posterior tibial tendon. The association of ligament failure with deformity has been discussed in numerous publications, but extensive documentation of the structures involved has not been performed. The purpose of this observational study was to identify the pattern of ligament involvement using standardized, high-resolution magnetic resonance imaging (MRI) in a series of 31 consecutive patients diagnosed with PTTI compared to an age matched control group without PTTI. METHOD: The structures evaluated by MRI were the posterior tibial tendon, superomedial and inferomedial components of the spring ligament complex, talocalcaneal interosseous ligament, long and short plantar ligaments, plantar fascia, deltoid ligament, plantar naviculocuneiform ligament, and tarsometatarsal ligaments. Structural derangement was graded on a five-part scale (0 to IV) with level 0 being normal and level IV indicating a tear of more than 50% of the cross-sectional area of the ligament. Standard flatfoot measurements taken from preoperative plain standing radiographs were correlated with the MRI grading system. RESULTS: Statistically significant differences in frequency of pathology in the PTTI group and controls were found for the superomedial calcaneonavicular ligament (p < 0.0001), inferomedial calcaneonavicular ligament (p < 0.0001), interosseous ligament (p = 0.0009), anterior component of the superficial deltoid (p < 0.0001), plantar metatarsal ligaments (p = 0.0002) and plantar naviculocuneiform ligament (p = 0.0006). The ligaments with the most severe involvement were the spring ligament complex (superomedial and inferomedial calcaneonavicular ligaments) and the talocalcaneal interosseous ligament. CONCLUSION: Ligament involvement is extensive in PTTI, and the spring ligament complex is the most frequently affected. Because ligament pathology in PTTI is nearly as common as posterior tibial tendinopathy, treatment should seek to protect or prevent progressive failure of these ligaments.

Reconstruction of the chronically failed deltoid ligament: a new technique.

BACKGROUND: Chronic deltoid ligament insufficiency that results in valgus tilt of the talus within the ankle mortise (stage IV adult acquired flatfoot) represents a difficult and so far unsolved problem in foot and ankle surgery. If left uncorrected, the deltoid failure with malalignment predisposes to early ankle arthritis and the need for ankle arthrodesis or possibly ankle arthroplasty. METHODS: Five consecutive patients with deltoid ligament insufficiency resulting in a valgus tilt were treated with a deltoid reconstruction. Reconstruction of the deltoid ligament was done by passing a peroneus longus tendon graft through a bone tunnel in the talus from lateral to medial and then through a second tunnel from the tip of the medial malleolus to the lateral tibia. RESULTS: At a minimum 2-year followup, all patients had correction of the talar tilt. One patient had 9 degrees of valgus tilt remaining compared to 15 degrees preoperatively, and the procedure was considered a failure. The remaining four patients had correction of the valgus tilt to 4 degrees or less. CONCLUSION: Although not uniformly successful, deltoid ligament reconstruction using a tendon graft through appropriate bone tunnels can reconstruct the deltoid ligament and correct the valgus talar tilt. Successful results were achieved when combined with correction of flatfoot deformity, which is considered a necessary part of the procedure.