Citations

AbstractTendon‐to‐bone integration is a great challenge for tendon or ligament reconstruction regardless of use of autograft or allograft tendons. We mineralized the tendon, thus transforming the tendon‐to‐bone into a “bone‐to‐bone” interface for healing. Sixty dog flexor digitorum profundus (FDP) tendons were divided randomly into five groups: (1) normal FDP tendon, (2) CaP (non‐extraction and mineralization without fetuin), (3) CaPEXT (Extraction by Na2HPO4 and mineralization without fetuin), (4) CaPFetuin (non‐extraction and mineralization with fetuin), and (5) CaPEXTFetuin (extraction and mineralization with fetuin). The calcium and phosphate content significantly increased in tendons treated with combination of extraction and fetuin compared to the other treatments. Histology also revealed a dense mineral deposition throughout the tendon outer layers and penetrated into the tendon to a depth of 200 µm in a graded manner. Compressive moduli were significantly lower in the four mineralized groups compared with normal control group. No significant differences in maximum failure strength or stiffness were found in the suture pull‐out test among all groups. Mineralization of tendon alters the interface from tendon to bone into mineralized tendon to bone, which may facilitate tendon‐to‐bone junction healing following tendon or ligament reconstruction. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1713–1719, 2013

Many neck pain complaints are associated with degenerated discs in cervical spine. Disc degeneration (DD) consists of cascading stages of events with complex changes in disc tissue properties. This results in deterioration of the ability of the disc to perform its function normally. Several biomechanical and biochemical changes occur in the disc with degeneration. Increase in motion segment stiffness and peak stresses in the posterior annulus are some of the gross changes that occur in the disc with degeneration.

Tendons and ligaments are soft connective tissues that play an important role in the musculoskeletal system. The tendon transmits the concentrated tensions generated by the muscle to the bone, and the ligaments stabilize and guide the movement between bones connected at the articulating joints. To perform these tasks, these soft connective tissues are uniquely built to bear load transmission, but are flexible enough to allow the changing direction in their paths of alignment. To accomplish these requirements, the tendons and ligaments have a hierarchy of highly aligned collagen structures consisting of fibrils, fascicles and fibers, along with the ground substance of proteoglycans and glycolipids to form the tendon and ligament tissues.

Collagen fibers in the annulus fibrosus (AF) play a significant role in maintaining the disc mechanical behavior. In healthy discs, AF fibers are concentrically arranged in a zigzag fashion. Tensile loads are transmitted to these fibers when the disc is loaded in compression. As a result, disc bulging occurs. Initiation and progression of mild cervical disc degeneration (DD) has been the subject of clinical concern [1]. The mild DD is associated with structural interruption in laminar organization of fibers in partial AF regions and incomplete length of fibers is a major form of structural interruption in AF fibers [2]. Moreover, a loss of lamellar fiber structure contributes to the progression of spinal deformity [3]. Past research have documented the biomechanical role of complete length of fibers in governing a healthy disc behavior [4]; however, there is a lack of clear understanding as to how incomplete length of fibers in different AF regions affect overall disc biomechanics and how they may play a role in initiating the propagation of DD. The focus of the current study is to investigate the disc biomechanical response due to incomplete length of fibers in outer, middle, and inner AF regions.

ABSTRACTWe compared the mechanical force of tendon‐to‐bone repair techniques for flexor tendon reconstruction. Thirty‐six flexor digitorum profundus (FDP) tendons were divided into three groups based upon the repair technique: (1) suture/button repair using FDP tendon (Pullout button group), (2) suture bony anchor using FDP tendon (Suture anchor group), and (3) suture/button repair using FDP tendon with its bony attachment preserved (Bony attachment group). The repair failure force and stiffness were measured. The mean load to failure and stiffness in the bony attachment group were significantly higher than that in the pullout button and suture anchor groups. No significant difference was found in failure force and stiffness between the pullout button and suture anchor groups. An intrasynovial flexor tendon graft with its bony attachment has significantly improved tensile properties at the distal repair site when compared with a typical tendon‐to‐bone attachment with a button or suture anchor. The improvement in the tensile properties at the repair site may facilitate postoperative rehabilitation and reduce the risk of graft rupture. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1720–1724, 2013

ABSTRACTAnimal models of joint contracture may be used to elucidate the mechanisms of arthrofibrosis. Patients with joint contracture commonly undergo surgical capsular release. Previous animal models of joint contracture do not simulate this aspect of arthrofibrosis. We hypothesize that a surgical capsular release will decrease the severity of arthrofibrosis in this rabbit model. A capsular contracture was surgically created in 20 skeletally mature rabbits. Eight weeks later, ten rabbits underwent capsular release, which consisted of elevation of the posterior capsule through a lateral incision and manipulation under anesthesia. Ten rabbits had a sham incision, without release (control group). Immediately after release or sham surgery, extension loss (calculated by subtracting the knee extension angle (degrees) of the operative limb from the nonoperative, contralateral limb) was measured using fluoroscopy. All animals were sacrificed following 16 weeks of postoperative free cage activity. At sacrifice, joint contracture was measured using a custom, calibrated device. The histology of the posterior joint capsule was assessed at sacrifice. All animals survived both operations without complications. Immediately after surgical release or sham surgery, the average extension loss was 129.2 ± 10.7° in the control group versus 29.6 ± 8.2° in the capsular release group (p = 0.0002). Following 16 weeks of remobilization, the average extension loss of the control and capsular release animals were 49.0 ± 12.7° and 36.5 ± 14.2°, respectively (p = 0.035). There were no histological differences between the two groups. In this animal model, a surgical capsular release decreased the extension loss (flexion contracture) immediately after surgery, as well as following sixteen weeks of remobilization. There were no histological changes detected in the posterior joint capsule. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1529–1532, 2013

Eleven fresh-frozen cadaver foot specimens were tested to define changes in tarsal alignment associated with flatfoot, or pes planus, a common clinical problem. The three-dimensional position of four bones (talus, calcaneus, navicular, and first metatarsal) relative to the fixed tibia was determined with a magnetic tracking system in the intact foot and flatfoot conditions. In the flatfoot, the average metatarsal-to-talar position difference was 11.7° ± 4.4° in abduction ( P < 0.0001), 10.4° ± 3.6° in dorsiflexion ( P < 0.0001), and 10.9° ± 6.0° in eversion ( P < 0.0001) compared with the intact foot. The average calcaneal-to-talar position difference was 2.2° ± 2.6° in abduction ( P = 0.0171) and 2.7° ± 2.0° in eversion ( P = 0.0012) compared with the intact foot. The average navicular-to-talar position difference was 13.6° ± 5.0° in abduction ( P < 0.0001), 10.5° ± 6.6° in dorsiflexion ( P = 0.0004), and 8.1° ± 3.8° in eversion ( P < 0.0001) compared with normal. The average talar-to-tibial position difference was −8.2° ± 3.2° in dorsiflexion ( P < 0.001) compared with the intact foot. The average arch height difference was 6.0 ± 2.7 mm ( P < 0.0001) less than the normal condition. The deformity associated with flatfoot is complex and occurs in multiple joints and in all three planes. An understanding of the normal and pathologic (flatfoot) conditions is necessary to surgically restore appropriate alignment and function in hindfoot reconstruction operations.

A major limitation of operations commonly performed for acquired flatfoot is inadequate correction of alignment. The authors defined the efficacy of two operations, deltoid ligament reconstruction and flexor digitorum longus tendon transfer, for treatment of posterior tibial tendon dysfunction with flatfoot deformity. Twelve fresh-frozen foot specimens were used. A flatfoot deformity was created, and, to simulate the midstance phase of gait, loads were applied axially to the plantar surface of the foot and to appropriate tendons. Foot position improved substantially after deltoid ligament reconstruction but not after flexor digitorum longus tendon transfer. The average increase in arch height after deltoid ligament reconstruction was 10.3 ± 8.9 mm and after flexor digitorum longus tendon transfer, −0.6 ± 2.0 mm. Mean arch height after deltoid ligament reconstruction was 2.2 ± 1.7 mm less than intact arch height and, after flexor digitorum longus tendon transfer, 13.2 ± 9.0 mm less than intact arch height. Improvement in metatarsal-talar, calcaneal-talar, and talar-tibial positions was significantly greater after deltoid ligament reconstruction than after flexor digitorum longus tendon transfer. Although the authors do not advocate clinical use, the deltoid ligament reconstruction was more effective than flexor digitorum longus tendon transfer in restoring arch alignment in flatfoot.

We defined the mechanical behavior of the foot after an operation for treatment of the flatfoot deformity, subtalar arthrodesis, and compared results with those from flexor digitorum longus tendon transfer. Twelve fresh-frozen human foot specimens were used. Supporting elements were sectioned to create a flatfoot deformity. To simulate midstance phase of gait, loads were applied axially to the plantar foot and to five tendons. Reduction of deformity in metatarsal-talar, calcaneal-talar, and talar-tibial positions was achieved and was significantly greater after subtalar arthrodesis operation than after flexor digitorum longus transfer.

We defined the relative contributions of six ligaments in stabilizing the arch of the foot: plantar aponeurosis, long-short plantar ligaments, plantar calcaneonavicular ligament (spring ligament), medial talocalcaneal ligament, talocalcaneal interosseous ligament, and tibionavicular portion of the deltoid ligament. Nineteen fresh-frozen human foot specimens were used. A load of 445 N was applied axially to simulate standing-at-ease posture. Three-dimensional positions of tarsal bones before and after ligament sectioning were determined with the use of a magnetic tracking device. The motions were presented in the form of screw axis displacements, quantitating rotation, and axis of rotation orientation. After sectioning one structure, the arch did not collapse on any specimen and there was no obvious change by visual inspection. There were, however, measurable changes in tarsal bone position. Metatarsal-to-talus total rotation difference was greatest with spring ligament and deltoid ligament sectioning, with an average of 2.1° ± 1.7° and 2.0° ± 0.2° difference, respectively. Calcaneus-to-talus rotation difference was greatest with talocalcaneal interosseous ligament sectioning, with an average of 1.7° ± 1.5°. The spring ligament, deltoid ligament, and talocalcaneal interosseous ligament were most important for arch stability.