Biomechanical Evaluation of a Tubular Braided Construct for Primary Deep Flexor Tendon Surgery

PURPOSE

Immediate postoperative mobilization has been shown to avoid adhesion formation and improve range of motion after flexor tendon repair. A tubular braided construct was designed to allow for these rehabilitation protocols.

METHODS

In this ex vivo study, 92 ovine flexor tendons were divided randomly into 2 equal groups. After creating a transection, the tendons of the first group were repaired using a tubular braided construct. This construct, consisting of a tubular braid of polypropylene and polyethylene terephthalate fibers, exerts a grasping effect on the tendon ends. The control group received a multistrand modified Kessler repair with a looped polydioxanone suture (PDS) 4-0 suture and a Silfverskiöld epitendinous repair using an Ethilon 6-0 suture. After the repair, a static and an incremental cyclic tensile test was performed until failure.

RESULTS

During the static test, the tubular braid resulted in a significantly higher load at 3 mm gap formation (86.3 N ± 6.0 vs 50.1 N ± 11.6), a higher ultimate load at failure (98.3 N ± 12.7 vs 63 N ± 11.1), higher stress at ultimate load (11.8 MPa ± 1.2 vs 8.1 MPa ± 3.1), and higher stiffness (7.1 N/mm ± 2.9 vs 8.7 N/mm ± 2.2). For the cyclic tests, survival analyses for 1-, 2- and 3-mm gap formation and failure demonstrated significant differences in favor of the tubular braided construct.

CONCLUSION

The tubular braided construct withstands the required loads for immediate rehabilitation not only in static tests, but also during cyclic tests. This is in contrast with the control group, where sufficient strength is reached during static tests, but failures occur below the required loads during cyclic testing.

CLINICAL RELEVANCE

The tubular braided construct provides a larger safety margin for immediate intensive rehabilitation protocols.

Scapular morphology of great apes and humans: A three-dimensional computed tomography-based comparative study

The primate scapula has been studied widely since its shape has been shown to correlate with how the forelimb is used in daily activities. In this study, we expand on the existing literature and use an image-based methodology that was originally developed for orthopaedic practice to quantify and compare the three-dimensional (3D) morphology of the scapula across humans and great apes. We expect that this image-based approach will allow us to identify differences between great apes and humans that can be related to differences in mobility and loading regime of the shoulder. We hypothesize that gorillas and chimpanzees will have a similar scapular morphology, geared towards stability and weight-bearing in knuckle-walking, whilst the scapular morphology of orangutans is expected to be more similar to that of humans given their high glenohumeral mobility associated with their suspensory lifestyle. We made 3D reconstructions of computed tomography scans of 69 scapulae from four hominid genera (Pongo, Gorilla, Pan and Homo). On these 3D bone meshes, the inferior glenoid plane was determined, and subsequently, a set of bony landmarks on the scapular body, coracoid, and acromion were defined. These landmarks allowed us to measure a set of functionally relevant angles which represent acromial overhang, subacromial space and coracoacromial space. The angles that were measured are: the delto-fulcral triangle (DFT), comprising the alpha, beta, and delta angle, the acromion-glenoid angle (AGA), the coracoid-glenoid centre-posterior acromial angle (CGA), the anterior tilt (TA CGA) and the posterior tilt of the CGA (PT CGA). Three observers placed the landmarks on the 3D bone meshes, allowing us to calculate the inter-observer error. The main differences in the DFT were found between humans and the great apes, with small differences between the great apes. The DFT of humans was significantly lower compared to that of the great apes, with the smallest alpha (32.7°), smallest delta (45.7°) and highest beta angle (101.6°) of all genera. The DFT of chimpanzees was significantly higher compared to that of humans (p < 0.01), with a larger alpha (37.6°) and delta angle (54.5°) and smaller beta angle (87.9°). The mean AGA of humans (59.1°) was significantly smaller (p < 0.001) than that of gorillas (68.8°). The mean CGA of humans (110.1°) was significantly higher (p < 0.001) than in orangutans (92.9°). Humans and gorillas showed mainly a posterior tilt of their coracoacromial complex whilst chimpanzees showed mainly an anterior tilt. The coracoacromial complex of the orangutans was not tilted anteriorly or posteriorly. With our image-based method, we were able to identify morphological features of the scapula that differed significantly between hominid genera. However, we did not find an overall dichotomy in scapular morphology geared towards high stability (Pan/Gorilla) or high mobility (Homo/Pongo). Further research is needed to investigate the functional implications of these differences in scapular morphology.

Flexor tendon repair using a reinforced tubular, medicated electrospun construct

A reinforced tubular, medicated electrospun construct was developed for deep flexor tendon repair. This construct combines mechanical strength with the release of anti-inflammatory and anti-adhesion drugs. In this study, the reinforced construct was evaluated using a rabbit model. It was compared to its components (a tubular, medicated electrospun polymer without reinforcement and a tubular braid as such) on the one hand to a modified Kessler suture as a control group. Forty New Zealand rabbits were randomly divided into two groups. Surgery was performed in the second and fourth deep flexor tendons of one hind paw of the rabbits in the two groups using four repair techniques. Biomechanical tensile testing and macroscopic and histological evaluations were performed at 3 and 8 weeks postoperatively. A two-way analysis of variance with pairwise comparisons revealed that the three experimental surgical techniques (a reinforced tubular medicated electrospun construct, tubular-medicated construct, and tubular braid as such) showed similar strength as that of a modified Kessler suture repair, which was characterized by a mean load at ultimate failure of 19.85 N (standard deviation [SD] 5.29 N) at 3 weeks and 18.15 N (SD 8.01 N) at 8 weeks. Macroscopically, a significantly different adhesion pattern was observed at the suture knots, either centrally or peripherally, depending on the technique. Histologically, a qualitative assessment showed good to excellent repair at the tendon repair site, irrespective of the applied technique. This study demonstrates that mechanical and biological repair strategies for flexor tendon repair can be successfully combined.

Surgical training during the COVID-19 pandemic - a single institution's trainee survey

BACKGROUND

Few studies have assessed the impact of COVID-19 on surgical training in low- and middle-income countries. The aim of this study was to survey the effect of the COVID-19 pandemic on postgraduate surgical training, research and registrar wellbeing in South Africa.

METHODS

A cross-sectional study was conducted as an online survey from 5 October 2020 to 1 December 2020. The study population was registrars from all surgical disciplines at the Faculty of Medicine and Health Sciences of Stellenbosch University. The survey consisted of 26 multiple-choice and five open-ended qualitative questions on the impact of COVID-19 on physical and mental wellbeing, skills acquisition and postgraduate research.

RESULTS

Of 98 surgical registrars, 35 (36%) responded. Twenty-three (65.7%) reported missed planned surgical rotations, 30 (85.7%) decreased surgical training time, and 22 (62.9%) reported a perceived decrease in training quality. Simulated skills training was only available to eight (22.9%) participants. Twenty-four (68.6%) experienced burnout and/or depression symptoms during the pandemic. Twenty-seven (77.1%) reported that postgraduate research was unaffected by the pandemic.

CONCLUSION

During the COVID-19 pandemic, surgical trainees at this institution reported a decrease in the quality of surgical training and skills acquisition and a negative impact on their mental wellbeing.

Impact of health technology assessment on preventive screening in Belgium: case studies of mammography in breast cancer, PSA screening in prostate cancer, and ultrasound in normal pregnancy

OBJECTIVE

To describe how scientific evidence has influenced healthcare policy making in Belgium in the field of sickness prevention for mammography, PSA testing in prostate cancer screening, and use of ultrasound in pregnancy.

METHODS

Review of published and gray literature and interviews with stakeholders and experts.

RESULTS

At the end of 1999, a systematic national/regional screening program had not yet been implemented for any of the three screening strategies. A systematic breast cancer screening program is being prepared for implementation only in Flanders. This limited impact can be attributed to the fragmentation in healthcare policy, the different options among the different regions, fragmentation in healthcare practice, the strong impact of healthcare stakeholders (provider groups and sickness funds) on decision making, and limited attention to scientific evidence in health policy and technology assessment.

CONCLUSIONS

Health technology assessment has had very little impact on policy and practice in use of mammography, PSA testing, and ultrasound in pregnancy in Belgium.