Does the proximal screw type affect stress and strain in pastern arthrodesis with locking plate in horses?

The implantation of unicortical cortex screws in the proximal hole of locking compression plates (LCP) has been recommended for proximal interphalangeal (PIP) arthrodesis in horses to prevent fractures resulting from stress risers in the proximal phalanx (P1). However, this cortex screw fixation technique may limit efficient dorsal compression of the PIP joint by the plate, potentially affecting the stability of the construct. In this study, we aimed to measure stress and strain in P1 and the plate using an ex vivo model of PIP arthrodesis in horses. We employed various implantation methods and proximal screw types in conjunction with two 5.5 mm transarticular cortex screws. Ten pairs of equine forelimbs were divided into four groups based on proximal screw placement: GUC (unicortically placed cortex screw), GBC (bicortically placed cortex screw), GUL (unicortically placed locking screw), and GBL (bicortically placed locking screw). We calculated the magnitude and direction of strain, strain ratio, and stress using strain gauges during an axial compression mechanical testing. The palmar surface of P1 exhibited higher stress and strains than the dorsal surface, with the plate part located at the articular level suffered more stress than the proximal part. Both the implantation method and proximal screw type significantly influenced the analyzed parameters. The GUC promoted greater changes in strain direction in the proximal portion of the P1. Bicortical placement of a cortex screw appears to be the most suitable option for filling the proximal hole of the LCP, because it allows effective dynamic compression via the plate and prevents abrupt shifts in the direction of the forces acting on the proximal part of P1 during loading.

Normal anatomic reference of pastern and coffin joints in Egyptian buffalo (Bubalus bubalis): A compared atlas of cross-sectional anatomy, magnetic resonance imaging and computed tomography.

The purpose of this study was to describe normal magnetic resonance imaging and computed tomographic anatomy of pastern and coffin joints in Egyptian buffalo using cadaveric distal limbs. This study was achieved using twelve fresh cadaveric distal limbs from adult healthy buffaloes of both sexes. These cadaveric limbs were scanned using a 1 Tesla MRI scanner and CT scanner, injected with red latex, frozen at -20°C for 1 week, and then sectioned into sagittal, dorsal and transverse slices. The obtained MR and CT images were selected to be matched with their corresponding anatomical cross-sections for identification and evaluation of the clinically correlated anatomical structures of the pastern and coffin joints. The difference in signal intensities on CT and MRI scans amongst the tissues allowed clear differentiation of major bone and soft tissue structures of the pastern and coffin joints. CT provided a high spatial resolution of bone and soft tissue structures, however, MRI allowed a better and higher resolution and definition between soft tissues. The current study provided a normal CT and MRI anatomic reference which could help veterinary clinicians for interpretation and diagnosis of the clinically affected pastern and coffin joints in buffalo.

Effects of tenectomy of the medial head of the deep digital flexor on the hindlimbs of healthy horses / Efeitos da tenectomia da cabeça medial do tendão flexor digital profundo nos membros posterior de cavalos saudáveis

The tenectomy of the medial head of the deep digital flexor (TMHDDF) is a minimally studied surgery used in cases of dorsal subluxation of the proximal interphalangeal joint of the hindlimb in horses. The TMHDDF was evaluated in six healthy horses by the degree of lameness, perimeter of the surgical site, the angle of the distal articular joints, and the linear and angular measures of the hoof. Thus, TMHDDF of the right hindlimb was performed and the contralateral limb was used as a control. Both, right and left limbs were evaluated before surgery, as well as at 15, 30, and 60 days after surgery aiming to evaluate the effects of the surgical procedure in healthy limbs. Data were compared by analysis of variance regarding days and limbs. Values below the significant level (P< 0.05) were analyzed using the Tukey's test. TMHDDF caused a mild increase of the toe length and the height of lateral heel (0.2cm in both), as well as a decrease of the angle of the proximal interphalangeal joint (2°) when comparing the left hindlimb to the right hindlimb, 30 and 60 days after surgery. Overall, TMHDDF did not cause significant changes in the evaluated variables up to the 60 days of surgery.(AU)

A tenectomia da cabeça medial do flexor digital profundo (TCMFDP) é uma técnica cirúrgica pouco estudada, indicada para equinos com subluxação dorsal da articulação interfalângica proximal do membro pélvico. A TCMFDP foi avaliada em seis equinos hígidos no grau de claudicação; na perimetria da área operada; nos ângulos articulares distais; e nas medidas lineares e angulares de parâmetros dos cascos. Nesse sentido, foi realizada a TCMFDP do membro pélvico direito, permanecendo o esquerdo como controle. Ambos os membros foram avaliados nos momentos pré-operatório (0) e 15, 30 e 60 dias após a cirurgia, sendo objetivo avaliar os efeitos do procedimento cirúrgico em membros hígidos. Para comparação dos dados entre momentos e membros, foi realizada análise de variância. Os valores inferiores ao de significância (P<0,050) foram submetidos ao teste de Tukey. A TCMFDP provocou discreto aumento (0,2cm, em ambos) do comprimento de pinça e da altura do talão lateral e redução no ângulo da articulação interfalângica proximal (2°) na comparação com o membro pélvico esquerdo aos 30 e 60 dias após a cirurgia no contralateral. Em geral, a TCMFDP não causou alterações influentes nos aspectos avaliados até 60 dias do experimento.(AU)