Introduction. Tendon injuries remain challenging, secondary healing and prolonged immobilisation result in suboptimal outcome. Previous study by our group showed that demineralised bone matrix (DBM) can result in faster healing of a tendon enthesis. The aim of this study is to test different ways augmenting tendon with DBM to enhance tendon repair and regeneration. Methods. DBM strips were prepared from tibias of mature ewes. Patella, patellar tendon and tibias were dissected and the distal 1 cm of the patellar tendon was excised. 4 models were designed;. Model-1, DBM strip was used to bridge the gap between the tendon and the tibial tuberosity. The DBM strip was stitched to the tendon using one bone anchor. Model-2, similar to model 1 with the use of 2 anchors. Model-3, similar to model 2, construct was off loaded by continuous thread looped twice through bony tunnels sited in the patella and in the tibial tuberosity. Model-4, similar to model 3 with 3 threads as off loading loop. All models were tested for pullout force and mode of failure. Results. The median failure force for model-1 (N=5) was 250N while for model-2 (N=5) was 290N. In model-3 and model-4 failure of the off loading loop was used as end point, 6 samples were tested in each model. Median failure force of model-3 was 767N and for model-4 was 934N. There was no statistical significance between model-1 and model-2 (p=0.249), however statistical significance was found between other models (p=< 0.006). Discussion. A study published in 1996 proved that cortical DBM can be used as ACL graft with evidence of ligamentisation. DBM provides a biologic scaffold with potential for use as ligament and tendon replacement. Our study shows that a tendon rupture can be augmented with DBM giving intial appropriate mechanical strength suitable for in-vivo use

Introduction. Avulsion of abductors from hip is a debilitating complication after total hip arthroplasty performed through a trans-gluteal approach. It results in intractable pain, Trendelenberg limp and instability of the hip. Techniques described for repairing these abductor tears including direct trans osseous repairs, endoscopic repair techniques, Achilles tendon allograft, Gluteus Maximus and Vastus Lateralis muscle transfers. The aim of our study was to assess improvement in pain, limp and abductor strength in patients operated upon surgically for confirmed abductor avulsion using a modified trans osseous repair and augmentation of repair with a Graft Jacket allograft acellular human dermal matrix (Graft jacket; Wright Medical Technology, Arlington, TN). Patients and Methods. In this prospective study we include 18 consecutive patients with hip abductor avulsions following a primary total hip arthroplasty through Hardinge approach for osteoarthritis. All the patients presented with pain around lateral aspect of hip, walking with a significant Trendelenberg limp and used a crutch or a stick in the opposite hand. Diagnosis was made by clinical examination and confirmed by MRI scans. Surgical Technique. Surgical procedure was through lateral approach using the old scar to mobilise combined aponeurosis of the Gluteal Medius and Gluteus Minimus from the bony bed on the ilium to permit advancement onto the trochanter. The conjoint Gluteus Medius and Minimus insertion was affixed to the greater trochanter with No.5 non absorbable trans-osseous suture using a Krackow stitch through a series of transverse tunnels made in anterior aspect of greater trochanter. An on lay augmentation (Fig. 1) of the osseo-tendinous junction was performed using a Graft Jacket matrix of 4 × 7 cms in size after rehydration according to the manufacturer's instructions. Results. At mean follow up of 22 months (15–34 months), pain improved in all patients with mean VAS score improving from 8.25 to 2.33 (p value-0.05). All the patients had improvement in their abductor strength with MRC grade 4 out of 5 in 16 patients and 3 out of 5 in 2 patients. Trendelenberg sign disappeared in all but two. Mean Harris hip score improved from 34.05 to 81.26 (p value-0.001). All patients had improvement in gait except mild noticeable limp in two patients.13 patients did not use any walking aids and five felt more secure using a walking stick in the contralateral hand. The mean SF-36 Physical component score was 53.47 and Mental component score was 56.07. Conclusions. The procedure is safe and associated with high patient satisfaction, without the morbidity of tendon or muscle transfers. The Graft Jacket Matrix provides biological bridging between the hip abductors and its insertion into greater trochanter. It provides a biological scaffold for cellular and vascular in-growth and constructive tissue remodelling. The described procedure appears to enhance the mechanical strength of repaired tendon immediately following surgery. The Graft Jacket allograft matrix has already been used successfully in rotator cuff repairs of shoulder and has showed encouraging results. The early success of this new procedure warrants further study with more patients, longer follow-up and possibly histological study of retrieved specimens