Patient-specific instrumentation for total knee arthroplasty does not match the pre-operative plan as assessed by intra-operative computer-assisted navigation.

PURPOSE: The introduction of patient-specific instruments (PSI) for guiding bone cuts could increase the incidence of malalignment in primary total knee arthroplasty. The purpose of this study was to assess the agreement between one type of patient-specific instrumentation (Zimmer PSI) and the pre-operative plan with respect to bone cuts and component alignment during TKR using imageless computer navigation. METHODS: A consecutive series of 30 femoral and tibial guides were assessed in-theatre by the same surgeon using computer navigation. Following surgical exposure, the PSI cutting guides were placed on the joint surface and alignment assessed using the navigation tracker. The difference between in-theatre data and the pre-operative plan was recorded and analysed. RESULTS: The error between in-theatre measurements and pre-operative plan for the femoral and tibial components exceeded 3° for 3 and 17% of the sample, respectively, while the error for total coronal alignment exceeded 3° for 27% of the sample. CONCLUSION: The present results indicate that alignment with Zimmer PSI cutting blocks, assessed by imageless navigation, does not match the pre-operative plan in a proportion of cases. To prevent unnecessary increases in the incidence of malalignment in primary TKR, it is recommended that these devices should not be used without objective verification of alignment, either in real-time or with post-operative imaging. Further work is required to identify the source of discrepancies and validate these devices prior to routine use. LEVEL OF EVIDENCE: II.

The role of tissue engineering in achilles tendon repair: a review.

Achilles tendon injuries are common but complex in nature. Healing occurs via scar tissue formation leading to poor patient outcomes. Currently surgical and non-surgical treatment leads to suboptimal tendon healing and has complications. Tissue engineering is an advancing field that can either augment surgical repair or provide an alternative method for Achilles tendon repair. This article will explore the principles behind tissue engineering in Achilles tendon repair. Furthermore it will describe the current literature regarding the different types of stem cells used in Achilles tendon repair, how different growth factors augment tendon repair, as well as the role of biomaterials in tissue engineering.

Growth factors and platelet rich plasma in anterior cruciate ligament reconstruction.

Platelet Rich Plasma (PRP) and growth factors have had encouraging results in several surgical specialties. Their use in orthopaedics is increasing and has been trialed in fracture management, spinal fusion and tendon and ligament healing. Anterior cruciate ligament (ACL) injuries are a significant economic burden and often require surgical reconstruction. This review article used laboratory and clinical studies to evaluate the effectiveness of PRP and growth factors as an adjunct to ACL reconstruction. Overall, the results of studies to date have been disappointing especially given the success in other specialties. PRP has been relatively successful in improving vascularization within the tibial tunnel but less so in the femoral tunnels. The targeting of specific growth factors seems to show more promise than generic PRP injections with vascular endothelial growth factor (VEGF), platelet derived growth factor (PDGF) and transforming growth factor-beta (TGF-ß) showing the most significant results in graft healing. Further trials are still required before a definitive conclusion can be reached.