Background Primary metatarsalgia of the lesser metatarsals is common and caused by mechanical overload of the affected metatarsal heads. Increased metatarsal length generally is believed to be a factor in the development of primary metatarsalgia. However, there is no clear biomechanical evidence supporting this theory. Questions/purposes We asked whether metatarsal length correlated with plantar-loading parameters under the corresponding metatarsal heads. Patients and Methods We prospectively followed two groups of patients 46 (51 feet) with and 45 (51 feet) without metatarsalgia. Each foot was physically examined and underwent standardized full-weightbearing radiography and dynamic pedobarography to assess maximal peak pressure and maximal force under the first, second, and third metatarsal heads. We correlated the relative length of the first and third metatarsals with the corresponding two plantar-loading parameters. We compared maximal peak pressure and maximal force in patients with metatarsalgia with those of symptom-free patients.Results The relative length of the first and third metatarsals did not correlate (r \ 0.13) with the maximal peak pressure or maximal force under the corresponding metatarsal heads. Maximal force under the first metatarsal head was decreased in the metatarsalgia group. There was no difference in maximal peak pressure between the metatarsalgia and nonmetatarsalgia groups. Conclusions Relative metatarsal length had no influence on plantar-loading parameters. Shortening of a symptomatic ray to decrease plantar-loading parameters cannot be supported from a biomechanical rationale.

Acute Achilles tendon ruptures are common sports injuries; however, treatment remains a clinical challenge. Studies show a superior effect of early mobilization and full weight bearing on tendon healing and clinical outcome; however, few data exist on structural and biomechanical characteristics in the early healing phase. This study investigated the histological and biomechanical characteristics of early mobilization and full weight bearing in an Achilles tendon rupture model. Eighty rats underwent dissection of a hindpaw Achilles tendon; 40 rats were treated conservatively and 40 underwent open repair of the transected Achilles tendon by suturing. Early mobilization and full weight bearing were allowed in both groups. At 1, 2, 4, and 8 weeks after tenotomy, tensile strength, stiffness, thickness, tissue characteristics (histological analysis), and length were determined. Dissected Achilles tendons healed in all animals during full weight-bearing early mobilization. One and 2 weeks after tenotomy, rats in the operative group showed increased tensile strength and stiffness compared with the nonoperative group. Repair-site diameters were increased at 1, 2, and 8 weeks after tenotomy. Tendon length was decreased in the operative group throughout observation, whereas the nonoperative group showed increased structural characteristics on the cellular level and a more homogeneous collagen distribution. Surgical treatment of dissected rat Achilles tendons showed superior biomechanical characteristics within the first 2 weeks. Conservative treatment resulted in superior histological findings but significant lengthening of the tendon in the early healing phase (weeks 1-8).

IntroductionAccessory ossicles of the foot are a common finding. Although mostly asymptomatic, they can gain clinical relevance by trauma or stress on the complex biomechanical system of the foot. There are few reports on the entity of symptomatic calcaneus secundarius. Furthermore, the current literature does not address the need for awareness of calcaneus secundarius as a differential diagnosis in cases of persistent posttraumatic ankle pain.Case presentationWe present the case of a 51-year-old Indo-European man with a medical history of persistent load-dependent ankle pain over 3 decades. At presentation after an acute ankle sprain, we diagnosed a traumatized calcaneus secundarius. Surgical excision led to a complete recovery. More than 1 year postoperative he is still asymptomatic.ConclusionsWith the presented case and review of the literature we demonstrate the clinical relevance of calcaneus secundarius. Depending on size and alignment, calcaneus secundarius can alter the biomechanics in the subtalar region generating pain at the ankle. If a patient has persistent sinus tarsi syndrome, a painful limited subtalar range of motion or repetitive ankle sprains, then calcaneus secundarius should be considered in differential diagnosis. Likewise when a fracture of the anterior process of the calcaneus or a calcaneonavicular coalition is suspected, calcaneus secundarius should be considered a possible diagnosis by all clinicians confronted with foot and ankle pain.