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Restriction of greater toe dorsiflexion without degeneration of the first metatarsophalangeal joint is defined as hallux limitus. We assume that in hallux limitus the limitation of greater toe dorsiflexion takes place in the terminal stance phase because of massive tightening of the calf and plantar structures. The current study investigated the role of a tight plantar fascial structure in impairing dorsiflexion of the greater toe. For the purpose of the study, 7 lower limbs from Thiel-fixated human cadavers were evaluated. To simulate double-limb standing stance, the tibia and fibula were mounted on a materials testing machine and constantly loaded with 350N. Additionally, the tendons of the specimens were loaded using a custom-made system. The plantar fascia was fixed to a clamp and tensioned using a threaded bar. Four different tensile forces were then applied to the plantar fascia (approximately 100, 200, 300, and 350 N) and the extension of the first toe was measured. The results show a significant positive correlation between the decrease in extension of the hallux and the tension applied to the plantar fascia reaching a maximum mean decrease of 4.2° (117% compared with the untightened situation) for an applied tension of 364N.

Background Biomechanical studies have shown a higher compressive force and higher torsional stiffness for fixation with three screws compared to two screws. However, clinical data to compare these fixation techniques is still lacking. Methods A retrospective analysis of 113 patients was performed, who underwent isolated subtalar fusion between January 2006 and April 2018. Results Revision arthrodesis was required in 8% (n = 6/36) for 3-screw-fixation and 38% (n = 35/77) for 2-screw-fixation. For 3-screw-fixation, non-union, was observed in 14% (n = 5/36) compared to 35% (n = 27/77) in 2-screw fixation. Non-union (p = .025) and revision arthrodesis (p = .034) were significantly more frequent in patients with 2 screws. A body mass index ≥30 kg/m2 (p = .04, OR = 2.6,95%CI:1.1–6.3), prior ankle-fusion (p = .017,OR = 4.4,95%CI:1.3–14.5) and diabetes mellitus (p = .04,OR = 4.9,95%CI:1.1–17.8) were associated with a higher rate of revision arthrodesis. Conclusions Our findings suggest that successful subtalar fusion is more reliably achieved with use of three screws. However, future prospective studies will be necessary to further specify this recommendation.

Background context The human iliolumbar ligament connects the transverse process of L5 to the iliac crest and contributes to lumbosacral stability and has been associated with low back pain. However, different opinions exist regarding the functional relevance of the ligament. Purpose In the present study, we analyze the regional molecular composition of the ligament extracellular matrix. Study design Special attention is given to the attachment sites, to determine whether the ligament is subjected to a certain mechanical environment. Methods Iliolumbar ligament samples, extending from one enthesis to the other, were removed from 11 cadavers and fixed in methanol. Cryosections were immunolabeled with a panel of antibodies directed against collagens, glycosaminoglycans, proteoglycans, matrix proteins, and neurofilament. Results The mid-substance of the ligament labeled for all the molecules normally found in dense fibrous connective tissue including types I, III, and VI collagen, versican, dermatan -, chondroitin 4 -, and keratan sulfate. However, both entheses were fibrocartilaginous and labeled for type II collagen, aggrecan, and chondroitin 6- sulfate. A common feature was fat between the fiber bundles near the entheses. Occasionally this fat contained nerve fibers. Conclusions The existence of fibrocartilaginous entheses suggests that the insertion sites of the ligament are subject to both tensile and compressive loading—probably because of insertional angle changes between ligament and bone during loading. Our findings support the suggestion that the iliolumbar ligament might play an important role in the stabilization of the lumbosacral junction.

The precise planning of metatarsal (MT) I length in hallux valgus surgery is important. However, currently no tool exists which allows the surgeon to reliably predict this parameter.30 virtual 3-dimensional hallux valgus surgeries were performed on varied deformation models based on cadaveric feet scans. The shortening of the first ray during distal metatarsal I osteotomy for different osteotomy angles were measured. An algebraic 2-dimensional calculation was done and compared to the results obtained from the 3-dimensional models.Inadvertent shortening of the first metatarsal bone can be as much as 8 mm depending on the amount of intermetatarsal angle (IMA) correction and osteotomy angle. Comparison of the 3 dimensional simulations and the 2 dimensional model resulted in a very strong correlation (R0.99 p0.00001). Based on our findings an anterior pointing osteotomy of approximately 10° is necessary to restore the length in distal metatarsal I hallux valgus surgery.A slight misdirection of the osteotomy plane in distal hallux valgus surgery may result in relevant unwanted alterations in first metatarsal bone length and triangulation by eye is insufficient in this complex geometrical situation without appropriate planning. The present study provides surgeons a practical tool to plan and control the change of first metatarsal length during hallux valgus procedure through exact orientation of the osteotomy angle. If no alteration of length is intended, it may be generalized that an anterior direction of the cut relative to the second metatarsal bone will preserve the length of the first metatarsal bone.