A method to study ligament-length patterns in situ with roentgenstereophotogrammetry, using strings of glued tantalum markers, was developed. The method was tested against a bone-to-bone marking method in five carpal ligaments in three specimens, whereby the hand was moved through dorsopalmar flexion and radioulnar deviation. The "glued-string" marking method was found to be superior to the bone-to-bone marking method. The length patterns obtained were found to be reproducible in the specimens and different from earlier expectations presented in the literature. The radiocapitate ligament seems to limit the displacements of the capitate in both radial and ulnar deviation, and dorsal flexion. The radiolunate ligament has the same effect for the lunate. Both the dorsal radiotriquetrum and the palmar triquetrocapitate ligaments seem to play a stabilizing role in the neutral position of the hand, whereas the radiotriquetrum ligament also has a function in palmar flexion and the triquetrocapitate ligament functions in dorsal flexion, ultimately resisting these excursions. These findings require confirmation in more extensive experiments, whereby the relationship between ligament length patterns and carpal motion axes is investigated.
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Hop tests are frequently used to determine return to sports (RTS) after anterior cruciate ligament reconstruction (ACLR). Given that bilateral deficits are present after ACLR, this may result in a falsely high limb symmetry index (LSI), since LSI is calculated as a ratio between the values of the limbs.HypothesisAthletes after ACLR would achieve LSI > 90% for the hop test. Secondly, athletes after ACLR demonstrate decreased jump distance on the single hop for distance (SLH) and triple leg hop for distance (TLH) and decreased number of hops for the side hop (SH) for both involved and uninvolved limbs compared to normative data of sex, age and type of sports matched healthy athletes.Materials and MethodsFifty-two patients (38 males mean age 23.9 ±3.5 yrs; 14 females mean age 21.7±3.5 years) who had undergone an ACLR participated in this study. Patients performed the 3 hop tests at a mean time of 7.0 months after ACLR. Hop distance, number of side hops and LSI were compared with normative data of 188 healthy athletes.ResultsThe differences between the involved limb and the uninvolved limb were significant in all hop tests (SLH p=0.003, TLH p=0.003 , SH p=0.018). For females, only significant between limb differences were found in the SLH (p=0.049). For both the SLH and the TLH, significant differences were found between the involved limb and the normative data (males; SLH p<0.001, TLH p<0.001; females; SLH p<0.001, TLH p=0.006) and between the uninvolved limb and the normative data for both males and females (males; SLH p<0.001, TLH p<0.001; females; SLH p=0.003, TLH p=0.038). For the SH, only significant differences were found between the involved limb and the normative values in males (p=0.033).ConclusionAthletes who have undergone an ACLR demonstrate bilateral deficits on hop tests in comparison to age and sex matched normative data of healthy controls. Using the LSI may underestimate performance deficits and should therefore be analyzed with caution when used as a criterion for RTS after ACLR.
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Individuals after anterior cruciate ligament reconstruction (ACLR) have a high rate of reinjury upon return to competitive sports. Deficits in motor control may influence reinjury risk and can be addressed during rehabilitation with motor learning strategies. When instructing patients in performing motor tasks after ACLR, an external focus of attention directed to the intended movement effect has been shown to be more effective in reducing reinjury risk than an internal focus of attention on body movements. While this concept is mostly agreed upon, recent literature has made it clear that the interpretation and implementation of an external focus of attention within ACLR rehabilitation needs to be better described. The purpose of this commentary is to provide a clinical framework for the application of attentional focus strategies and guide clinicians towards effectively utilizing an external focus of attention in rehabilitation after ACLR.
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