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Background: Disruption of the distal tibia and fibula articulation or syndesmosis can occur without fracture, and isolated syndesmotic disruption is often treated operatively. Following syndesmotic screw removal, a period of protected weight-bearing usually follows to allow the screw holes to heal. Our hypothesis was that supplementing transsyndesmotic fixation with a one-third tubular plate would potentially increase the torsional stiffness about the ankle, thus reducing the risk of fracture after screw removal and potentially allowing a faster return to weight-bearing and sport., Methods: Ten pairs of fresh frozen cadaveric specimens were divided into 2 groups. In group 1 (7 pairs), each left extremity underwent the placement, and subsequent removal, of a 4.5-mm transsyndesmotic screw in a tricortical fashion. The matching right extremity underwent the same procedure but with the addition of a one-third tubular plate, which remained in situ after screw removal. In group 2 (3 pairs), the left specimens had a screw placed and removed while the right limbs remained intact. All specimens were tested under an axial preload and a torsional load until failure., Results: In group 1, the results demonstrated an increase in torsional stiffness in 5 of 7 specimens with supplemental fixation of a one-third tubular plate. In group 2, the presence of the screw hole alone reduced the torsional stiffness in all specimens tested when compared with intact specimens. However, neither of these differences were statistically significant., Conclusion: From this study, we can conclude that the use of supplementary one-third tubular plate fixation demonstrated a trend toward increasing the torsional stiffness following transsyndesmotic screw removal., Clinical Relevance: We believe the trend toward improved stiffness justifies the continued use of our technique, although further studies are necessary to confirm it.

Background: To prevent hemorrhage, fibrin clot formation, and subsequent activation of the inflammatory response, surgical preparation for articular cartilage regeneration should avoid penetration of the subchondral bone plate., Hypothesis: Current surgical procedures with ring curettes do not violate the subchondral bone plate., Study Design: Controlled laboratory study., Methods: The subchondral bone plates of normal human (n = 5) or sheep (n = 12) cadaver femoral condyles were prepared in vitro using either traditional debridement for autologous chondrocyte implantation/transplantation (ACI/ACT) or a modified approach aimed at deliberately violating the subchondral bone plate (ie, brute force). Effects were analyzed by light microscopy. In addition, subchondral bone plates of osteoarthritic (OA) human knees undergoing total knee arthroplasty (n = 5) or normal sheep knees (n = 5) were prepared in vivo. To approximate normal/regular wear, in humans, only OA samples with maximally grade 3A (International Cartilage Repair Society score) were used., Results: In both human and sheep (in vitro), no penetration of the subchondral bone plate was observed by either standard preparation or brute force. In vivo, standard preparation of human or sheep knees also did not violate the tidemark line. Human and sheep specimens prepared by brute force, however, occasionally showed areas with an open bone marrow space., Conclusion: Traditional debridement techniques for ACI/ACT using a ring curette do not violate the normal subchondral bone plate in vitro or in vivo. Even in OA knee joints, the bone plate is only violated by brute force. Therefore, the standard technique appears suitable for studies on cartilage regeneration in cases of traumatic and possibly even osteoarthritic defects., Clinical Relevance: The described surgical preparation technique is the traditional debridement technique for the ACI/ACT. The classic indication for the ACI/ACT is an articular cartilage injury, common in athletes.

Background: Medial opening wedge distal tibial osteotomy, a relatively new technique for treatment of intermediate ankle joint arthritis, is a technically demanding procedure that requires preoperative planning to determine the size of the wedge that will restore anatomic alignment of the joint surface. The purpose of this study was to facilitate the preoperative planning process for distal tibial osteotomy by determining angular correction obtained with various wedge heights., Methods: Measurements of the distal tibia were taken from cadaver specimens to develop a database of average distal tibial widths. A distal tibial osteotomy was then done on the cadaver specimens with the placement of wooden block wedges of various heights at the osteotomy site. Preoperative and postoperative radiographic measurements of the joint surface angle were obtained on all specimens. The measured amount of angular change was compared to the mathematically predicted angular change using the formula tan theta = H/W., Results: The mathematical model accurately predicted the amount of measured angular correction of the distal tibial articular surface. There was an approximate 2-degree angular change of the articular surface per millimeter of wedge height. As the tibial width increased, a smaller amount of angular correction per millimeter of wedge height was noted, and as wedge height increased with the same tibial width, less angular correction was obtained per millimeter of wedge height., Conclusion: With appropriate preoperative planning, an accurate prediction can be made as to the amount of ankle joint correction that should be obtained with surgery. The size of the wedge that will provide the desired amount of correction can be accurately determined preoperatively.

Tendon transfer techniques in the foot and ankle are used for tendon ruptures, deformities, and instabilities. This fresh cadaver study compares the tendon fixation strength in 10 paired specimens by performing a tendon to tendon fixation technique or using 7 x 20-25 mm bioabsorbable interference-fit screw tendon fixation technique. Load at failure of the tendon to tendon fixation method averaged 279N (Standard Deviation 81N) and the bioabsorbable screw 148N (Standard Deviation 72N) [p = 0.0008]. Bioabsorbable interference-fit screws in these specimens show decreased fixation strength relative to the traditional fixation technique. However, the mean bioabsorbable screw fixation strength of 148N provides physiologic strength at the tendon-bone interface.

The purpose of this study was to compare the initial fixation strengths of bioabsorbable screws for tendon transfers in the foot and ankle when the pilot hole size varied. A 7 x 20 mm screw was used with 5.5 mm and 6.5 mm drill holes, and a 5 x 20 mm screw was used with 3.9 mm and 4.5 mm drill holes. Biomechanical testing was performed on each tendon transfer in cadaver specimens. A paired t-test showed no significant difference in pullout strength when pilot hole size varied between 79 to 93% of the screw size for the 7 mm screw and 78 to 90% of the screw size for the 5 mm screw. Previous studies have found a critical value of tendon tension equaling 50 N with passive dorsiflexion of the foot. With an average value of approximately 170 N, the 7 mm screw provided three times the requisite strength. The 5 mm screw provided 1.5 times the requisite strength, but the transfer was technically more difficult.

The bone density of cadaveric specimens is highly variable and has a significant effect on the results of biomechanical testing but it is not often assessed before testing is performed in the lab. Bone mineral density (BMD) tests such as dual X-ray absorptiometry (DXA) are widely available, easy to perform and correlate highly and significantly with bone strength in many modes of failure. We present the results of two different studies performed on cadaveric foot and ankle specimens. In these studies the results vary significantly according to BMD, and this effect is not always eliminated with the use of matched pairs of cadaveric specimens.