The ability of mesenchymal stem cells (MSCs) to differentiate in vitro into chondrocytes, osteocytes and myocytes holds great promise for tissue engineering. Skeletal defects are emerging as key targets for treatment using MSCs due to the high responsiveness of bone to interventions in animal models. Interest in MSCs has further expanded in recognition of their ability to release growth factors and to adjust immune responses.

Despite their increasing application in clinical trials, the origin and role of MSCs in the development, repair and regeneration of organs have remained unclear. Until recently, MSCs could only be isolated in a process that requires culture in a laboratory; these cells were being used for tissue engineering without understanding their native location and function. MSCs isolated in this indirect way have been used in clinical trials and remain the reference standard cellular substrate for musculoskeletal engineering. The therapeutic use of autologous MSCs is currently limited by the need for ex vivo expansion and by heterogeneity within MSC preparations. The recent discovery that the walls of blood vessels harbour native precursors of MSCs has led to their prospective identification and isolation. MSCs may therefore now be purified from dispensable tissues such as lipo-aspirate and returned for clinical use in sufficient quantity, negating the requirement for ex vivo expansion and a second surgical procedure.

In this annotation we provide an update on the recent developments in the understanding of the identity of MSCs within tissues and outline how this may affect their use in orthopaedic surgery in the future.

Cite this article: Bone Joint J 2014;96-B:291–8.

The Achilles tendon is the most commonly ruptured tendon in the body and yet its management remains controversial due to potential surgical complications. We believe that primary repair using LARS ligament augmentation, combined with early mobilisation will significantly reduce all these potential problems and lead to improved functional outcomes.

Nine patients with acute Achilles tendon ruptures underwent primary repair using augmentation with a Ligament Augmentation and Reconstruction System (LARS) ligament. Day one postoperatively each patient was started on active range of motion exercises. Clinical parameters, isokinetic strength and outcome measurements (The American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot score and Lower Extremity Functional Scale (LEFS) was utilised to assess pain and function, Tegner score to evaluate activity) were evaluated at an average follow-up of 17 months. Complications, if any, were also recorded.

There were no re-ruptures and all patients returned to normal work (average time 9.2 weeks) and all but one returned to their previous level of recreational sporting activity (average time 20.8 weeks). The postoperative performance testing showed positive results with the mean decrease in calf circumference of affected leg was 1.0 cm (range, −0.5 to 2.0), and every patient was able to perform at least one heel-raise with the mean heel raise difference being −3.8 repetitions (range, −1 to −10 reps) when compared to the other leg. In terms of functional outcomes, all patients reported very good results. The mean AOFAS score postoperatively was 83.4% (range, 74% to 100%) and the mean LEFS score was 82.5% (range, 45 to 100%). The mean preoperative Tegner score was 4.75 (range, 2 to 8) and the postoperative score was 3.75 (range, 2 to 7).

The results of our preliminary clinical series indicate that LARS ligament repair of acute Achilles tendon ruptures provides a reliable and effective technique for repair. It eliminates the need for graft harvesting, it decreases postoperative complications, but most importantly, patients have improved functional outcomes.