Motion Analysis of the Wrist and Finger Joints in Sport Climbing

Climbing is a fast-growing sport, with one of the most common injuries being a rupture of the finger flexor tendon pulley. The strain on pulleys increases as finger joints flex. However, to our knowledge, no study has conducted a kinematic analysis of climbers' fingers. Thus, this study aimed to examine finger kinematics during typical climbing tasks. Eleven elite climbers performed a sequence of four climbing moves, which were recorded by an optical motion capture system. Participants used crimp, half-crimp, and open-hand grips for three trials each, with the fourth condition involving campusing using any grip except crimp. Mean proximal interphalangeal joint (PIP) flexion during the holding phase was 87° (SD 12°), 70° (14°) and 39° (27°) for the crimp, half-crimp and open-hand grip, respectively. Hence, inter-individual PIP flexion ranges overlap between different gripping conditions. Two different movement patterns emerged in the open-hand grip, possibly influenced by the use of the little finger, leading to varying degrees of flexion in the middle and ring fingers. Avoiding little finger usage in the open-hand grip may reduce load during pulley rupture rehabilitation. The implications of PIP joint angle variability on individual pulley injury risk or prevention warrant further investigation. Motion capture proved effective for understanding finger kinematics during climbing and could guide future studies on pulley injury risk factors.

Palmar Shift of the Proximal Interphalangeal Joint in Different Grip Positions as a Potential Risk Factor for Periphyseal Injuries in Adolescent Climbers

INTRODUCTION

The aim of this study was to evaluate different grip positions as a contributing factor for primary periphyseal stress injuries of the finger phalanges in climbing.

METHODS

Ultrasound imaging of the proximal interphalangeal joint was performed on 37 asymptomatic adolescent climbers. Longitudinal images were obtained of middle and ring fingers of both hands in different grip positions (open, half-open, and crimp), unloaded and loaded. The translation between the dorsal head of the proximal phalanx and the shaft of the middle phalanx was measured in an unloaded and loaded situation for all grip positions. The resulting difference was determined as the palmar shift.

RESULTS

The mean age of the study population was 13 y. Results showed a palmar shift of 0.57 mm in a loaded crimp grip position compared to 0.13 mm in an open position and 0.20 mm in a half-open grip position. With a P value of <0.001, this shift was significantly higher in a crimp grip position compared to open or half-open grip positions.

CONCLUSIONS

This leads to an increase in joint incongruity and much higher peak forces on the dorsal aspect of the epiphyseal-physeal-metaphyseal complex, which is particularly vulnerable during the adolescent growth spurt. Thus, climbing and training behavior should be adapted accordingly during this phase by avoiding the crimp grip position until epiphyseal fusion.

Improved suture pullout through genipin-coated sutures in human biceps tendons with spatially confined changes in cell viability

BACKGROUND

The suture-tendon interface often constitutes the point of failure in tendon suture repair. In the present study, we investigated the mechanical benefit of coating the suture with a cross-linking agent to strengthen the nearby tissue after suture placement in human tendons and we assessed the biological implications regarding tendon cell survival in-vitro.

METHODS

Freshly harvested human biceps long head tendons were randomly allocated to control (n = 17) or intervention (n = 19) group. According to the assigned group, either an untreated or a genipin-coated suture was inserted into the tendon. 24 h after suturing, mechanical testing composed of cyclic and ramp-to-failure loading was performed. Additionally, 11 freshly harvested tendons were used for short-term in vitro cell viability assessment in response to genipin-loaded suture placement. These specimens were analyzed in a paired-sample setting as stained histological sections using combined fluorescent/light microscopy.

FINDINGS

Tendons stitched with a genipin-coated suture sustained higher forces to failure. Cyclic and ultimate displacement of the tendon-suture construct remained unaltered by the local tissue crosslinking. Tissue crosslinking resulted in significant cytotoxicity in the direct vicinity of the suture (<3 mm). At larger distances from the suture, however, no difference in cell viability between the test and the control group was discernable.

INTERPRETATION

The repair strength of a tendon-suture construct can be augmented by loading the suture with genipin. At this mechanically relevant dosage, crosslinking-induced cell death is confined to a radius of <3 mm from the suture in the short-term in-vitro setting. These promising results warrant further examination in-vivo.

Feasibility of the annulus fibrosus repair with in situ gelating hydrogels - A biomechanical study

The surgical standard of care for lumbar discectomy leaves the annulus fibrosus (AF) defect unrepaired, despite considerable risk for a recurrent herniation. Identification of a viable defect repair strategy has until now been elusive. The scope of this ex vivo biomechanical study was to evaluate crosslinking hydrogels as potentially promising AF defect sealants, and provide a baseline for their use in combination with collagen scaffolds that restore disc volume. This study directly compared genipin crosslinked fibrin hydrogel (FibGen) as a promising preclinical candidate against a clinically available adhesive composed of glutaraldehyde and albumin (BioGlue). Forty-two bovine coccygeal functional spine units (FSU) were randomly allocated into four groups, namely untreated (control, n = 12), repaired with either one of the tested hydrogels (BioGlue, n = 12; FibGen, n = 12), or FibGen used in combination with a collagen hydrogel scaffold (FibGen+Scaffold, n = 6). All specimens underwent a moderate mechanical testing protocol in intact, injured and repaired states. After completion of the moderate testing protocol, the samples underwent a ramp-to-failure test. Lumbar discectomy destabilized the FSU as quantified by increased torsional range of motion (28.0° (19.1, 45.1) vs. 41.39° (27.3, 84.9), p<0.001), torsional neutral zone (3.1° (1.2, 7.7) vs. 4.8° (2.1, 12.1), Z = -3.49, p < 0.001), hysteresis(24.4 J (12.8, 76.0) vs. 27.6 J (16.4, 54.4), Z = -2.61, p = 0.009), with loss of both disc height (7.0 mm (5.0, 10.5) vs 6.1 mm (4.0, 9.3), Z = -5.16, p < 0.001) and torsional stiffness (0.76 Nmdeg-1 (0.38, 1.07) vs. 0.66 Nmdeg-1 (0.38, 0.97), Z = -3.98, p < 0.001). Most FibGen repaired AF endured the entire testing procedure whereas only a minority of BioGlue repaired AF and all FibGen+Scaffold repaired AF failed (6/10 vs. 3/12 vs. 0/6 respectively, p = 0.041). Both BioGlue and FibGen+Scaffold repaired AF partially restored disc height (0.47 mm (0.07, 2.41), p = 0.048 and 1.52 mm (0.41, 2.57), p = 0.021 respectively) compared to sham treatment (0.08 mm (-0.63, 0.88)) whereas FibGen-only repaired AF had no such effect (0.04 mm (-0.73, 1.13), U = 48.0, p = 1). The AF injury model demonstrated considerable change of FSU mechanics that could be partially restored by use of an AF sealant. While inclusion of a volumetric collagen scaffold led to repair failure, use of FibGen alone demonstrated clinically relevant promise for prevention of mechanical reherniation, outperforming an FDA approved sealant in this ex vivo test series.

Trapeziectomy With Suspension-Interposition Arthroplasty for Thumb Carpometacarpal Osteoarthritis: A Randomized Controlled Trial Comparing the Use of Allograft Versus Flexor Carpi Radialis Tendon

PURPOSE

The objective of this randomized controlled trial was to compare the 12-month postoperative Michigan Hand Outcomes Questionnaire (MHQ) total score between patients with osteoarthritis (OA) at the first carpometacarpal (CMC I) joint who underwent trapeziectomy with suspension-interposition arthroplasty using the flexor carpi radialis (FCR) tendon and those receiving a human dermal collagen template (allograft).

METHODS

We included 60 patients with CMC I OA who met the indications for surgery. They were randomized into 1 of 2 groups: trapeziectomy using the FCR tendon or trapeziectomy with the allograft for suspension-interposition. Patients completed a set of questionnaires including the MHQ and were clinically assessed at baseline, 6 weeks, and 3, 6, and 12 months after surgery. Complications were recorded.

RESULTS

We operated on 29 patients using the FCR tendon; 31 patients received an allograft. Baseline MHQ total scores significantly increased from 51 (95% confidence interval [CI], 46-56) to 83 (95% CI, 78-87) and 53 (95% CI, 47-58) to 76 (95% CI, 69-84) by 12 months in the FCR and allograft groups, respectively. We found similar outcomes for both groups at all follow-up assessments. Five complications occurred in the FCR group, and 10 in the allograft group. Revision surgery was required for one allograft patient.

CONCLUSIONS

The use of the FCR tendon or allograft for trapeziectomy with suspension-interposition arthroplasty in patients with CMC I OA leads to similar outcomes with more complications, mainly tendon irritations, associated with the latter. Therefore, we only use the allograft in cases of severe instability requiring a larger amount of suspension-interposition material or for revision procedures after failed suspension-interposition with the FCR tendon.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic I.

Effects of laboratory housing on exploratory behaviour, novelty discrimination and spatial reference memory in a subterranean, solitary rodent, the Cape mole-rat (Georychus capensis)

A large number of laboratory and field based studies are being carried out on mole-rats, both in our research group and others. Several studies have highlighted the development of adverse behaviours in laboratory animals and have emphasised the importance of enrichment for captive animals. Hence we were interested in evaluating how laboratory housing would affect behavioural performance in mole-rats. We investigated exploratory behaviour, the ability to discriminate between novel and familiar environments and reference memory in the solitary Cape mole-rat (Georychuscapensis). Our data showed that both wild and captive animals readily explore open spaces and tunnels. Wild animals were however more active than their captive counterparts. In the Y maze two trial discrimination task, wild animals failed to discriminate between novel and familiar environments, while laboratory housed mole-rats showed preferential spatial discrimination in terms of the length of time spent in the novel arm. The performance of the laboratory and wild animals were similar when tested for reference memory in the Y maze, both groups showed a significant improvement compared to the first day, from the 3rd day onwards. Wild animals made more mistakes whereas laboratory animals were slower in completing the task. The difference in performance between wild and laboratory animals in the Y-maze may be as a result of the lower activity of the laboratory animals. Laboratory maintained Cape mole-rats show classic behaviours resulting from a lack of stimulation such as reduced activity and increased aggression. However, they do display an improved novelty discrimination compared to the wild animals. Slower locomotion rate of the laboratory animals may increase the integration time of stimuli, hence result in a more thorough inspection of the surroundings. Unlike the captive animals, wild animals show flexibility in their responses to unpredictable events, which is an important requirement under natural living conditions.