Fixation of tendon transfers about the foot in children typically involves creating a bone tunnel through which a suture is passed and tied over an external button. An internal suspension system, such as the Endobutton (Smith & Nephew) is an alternative fixation method which has demonstrated excellent fixation strength and minimal intraosseous tunnel displacement in various adult procedures. Application of the Endobutton technique has no risk of skin ulceration, does not require suture removal and may provide more secure fixation. The purpose of this study is to compare the biomechanical properties of the external button and Endobutton fixation techniques. Our primary outcome measure was intra-osseous displacement of the suture, during both static and dynamic loading, in cadaver feet.

Nine adult cadaver feet were utilised. A bone tunnel was drilled in the lateral cuneiform and #1 braided non-absorbable suture was passed through the tunnel. One end was secured to a carabiner to be attached to the materials testing system and the other to the fixation device. The external button and Endobutton fixation techniques were tested once in each cadaver, randomising the order of testing to minimise bias. Each fixation technique underwent static and dynamic cyclic loading. A custom Matlab script was used to process video and materials testing system data. The relative displacement of the suture within the bone tunnel, as a function of time and load magnitude, was recorded during static and dynamic cyclic loading. Both fixation groups were analysed and compared for statistical significance using a paired T-test and an alpha value of 0.05.

The Endobutton group had significantly less displacement within the bone tunnel, during both static and dynamic loading, than the external button. The average displacement during static loading was 0.42 mm for the Endobutton and 2.17 mm for the external button (p=0.0019). Similarly, during dynamic cyclic loading, the mean displacement was 0.32 mm for the Endobutton and 0.66 mm for the external button (p=0.0115).

The Endobutton internal suspension technique demonstrates significantly less displacement during static and dynamic loading than the external button, during biomechanical testing in cadaver feet. The Endobutton may provide superior fixation than the traditional external button technique for tendon transfers in children. In addition, this technique avoids the risk of skin ulceration from the button and the need for suture removal.

There is currently no standardised complication grading classification routinely used for paediatric orthopaedic surgical procedures. The Clavien-Dindo classification used in general surgery was modified and validated in 2011 by Sink et al. and has been used regularly to classify complications following hip preservation surgery. The aim of this study was to adapt and validate Sink et al.'s modification of the Clavien-Dindo classification system for grading complications following surgical interventions of the upper and lower extremities and spine in paediatric orthopaedic patients.

Sink et al.'s modification of the Clavien-Dindo classification system was further modified for paediatric orthopaedic procedures. The modified grading scheme was based on the treatment required to treat the complication and the long term morbidity of the complication. Grade I complications do not require deviation from standard treatment. Grade II complications deviate from the normal post-operative course and require outpatient treatment. Grade III complications require investigations, re-admission or re-operation. Grade IV complications are limb or life threatening or have a potential for permanent disability (IVa: with no long term disability and IVb: with long-term disability). Grade V complications result in death. Forty-five complication scenarios were developed. Seven paediatric orthopaedic surgeons were trained to use the modified system and they each graded the scenarios on two occasions. The scenarios were presented in a different random order each time they were graded. Fleiss' and Cohen's k statistics were performed to test for inter-rater and intra-rater reliabilities, respectively.

The overall Fleiss' k value for inter-rater reliability was 0.772 (95% CI, 0.744–0.799). The weighted k was 0.765 (95% CI, 0.703–0.826) for Grade I, 0.692 (95% CI, 0.630–0.753) for Grade II, 0.733 (95% CI, 0.671–0.795) for Grade III, 0.657(95% CI, 0.595–0.719) for Grade IVa, 0.769 (95% CI, 0.707–0.83) for Grade IVb and 1.000 for Grade V (p value <0.001). The Cohen's k value for intra-rater reliability was 0.918 (95% CI, 0.887–0.947). These tests show that the adapted classification system has high inter- and intra-rater reliabilities for grading complications following paediatric orthopaedic surgery.

Given the high intra- and inter-rater reliability and simplicity of this system, adoption of this grading scheme as a standard of reporting complications in paediatric orthopaedic surgery could be considered. Since the evaluation of surgical outcomes should include the ability to reliably grade surgical complications, this reproducible, reliable system to assess paediatric surgical complications will be a valuable tool for improving surgical practices and patient outcomes.