Biomechanical assessment of an alternative method of staple fixation for anchoring the Bone Patellar Tendon Bone graft to the tibia.

INTRODUCTION: The Anterior cruciate ligament (ACL) is the most commonly injured ligament around the knee and is best reconstructed with a biological graft. For ideal graft fixation, there should be sufficient initial strength to avoid failure of fixation and sufficient stiffness to restore the stability of the knee and to avoid gradual loosening in the post-operative period.When considering fixation of Bone Patellar Tendon Bone (BPTB) grafts to the tibia, the interference screw is considered to be the gold standard. As an alternative, we have used of staples and stainless steel (SS) wire to anchor the BPTB graft to the tibia and femur. The aim of this study was to assess the biomechanical efficacy of this fixation technique for anchoring the BPTB graft to the proximal tibia. We used a bovine model to compare three fixation techniques -interference screw, braided polyester sutures tied to a screw post and SS wire tied to a staple. MATERIALS AND METHODS: Fifteen fresh bovine knees specimens were used for the study. The patella was fixed to a load cell and the construct was pre-tensioned to 40N to allow for creep of the tendon. The BPTB graft was fixed to the tibia using the three fixation techniques - the interference screw, polyester suture tied to a post, and SS wire anchored to a staple. After fixation, the graft was subjected to a single load to failure test, and the forces generated were recorded. The ultimate failure load (the pullout strength), stiffness, and mode of failure were noted. RESULTS: In the single load-to-failure biomechanical testing, the ultimate failure load and stiffness for Staple with SS wire were 726.40N and 61.9N/mm respectively. For the screw post and polyester suture, it was 733.20N and 53.22N/mm, and for Interference screw - 594.00N and 79.50 N/mm respectively. There was no statistically significant difference in the stiffness or ultimate failure load between the three fixation techniques. The graft fixation using interference screws failed at the bone- tunnel interface by slippage of the bone block from the tunnel in all 5 specimens. In all 5 of the specimens fixed with polyester suture and the screw post, the fixation failed when the polyester suture snapped. When the SS wire and staple construct was stressed, the graft failed as the SS wire cut through the graft in 4 specimens, and in the fifth construct, the knot over the staple unraveled as the load was applied. CONCLUSION: The biomechanical properties of BPTB graft fixation with SS wire tied to a staple is similar to that of other fixation devices like the interference screw and suture post. This technique provides a simple, yet effective fixation for the graft - but needs further clinical assessment.

Is pre-operative assessment of coagulation profile with Thrombelastography (TEG) useful in predicting venous thromboembolism (VTE) following orthopaedic surgery?

INTRODUCTION: Epidemiologic data on the incidence of venous thromboembolism (VTE) in Indian population vary widely. Most studies show that the incidence of VTE is lower in Asian patients than in Western population. Screening tools to identify high-risk patients should enable us to reduce this complication. METHODS: The incidence of VTE in 101 patients who underwent knee or hip arthroplasty, or surgery for hip fractures, without chemoprophylaxis for deep vein thrombosis (DVT) was documented. Diagnosis of DVT was made with Duplex ultrasonography. We also assessed the usefulness of pre-operative assessment of the hypercoagulable status of the patient in predicting the occurrence of VTE, using the Thrombelastography (TEG) test. RESULTS: The incidence of DVT in the study population was 7%. Six of the 7 patients who developed DVT had surgery for hip fractures, while one had knee replacement. The thrombus was above the knee joint level in 6 of the 7 patients. Pre-operative TEG was positive in only one of the 7 patients, but was positive in 37 of the remaining 94 patients. CONCLUSION: Incidence of DVT in the study population is sufficiently high to recommend some form of prophylaxis to prevent VTE following hip and knee surgery. Pre-operative assessment of the patients' coagulation status with Thrombelastography does not predict the risk of VTE. The use of other lab parameters that could help in selective chemoprophylaxis needs to be explored.

Distal femoral rotational alignment in the Indian population - An important consideration in total knee arthroplasty.

OBJECTIVE: To measure the angular relationships of distal femoral rotational axes in the normal Indian population. MATERIALS AND METHODS: Magnetic Resonance Imaging (MRI) scans of the knee of 40 Indian subjects were used to define the posterior condylar axis, the transepicondylar axis and the Whiteside's line (anteroposterior axis). The posterior condylar angle (PCA) - the angle between the posterior condylar axis and the transepicondylar axis, and the Whiteside-epicondylar angle (W-EP angle) were then calculated. RESULTS: The mean posterior condylar angle in the Indian knee was 4.67° and the mean Whiteside-epicondylar angle was 92.7°. CONCLUSION: There are differences in the distal femoral rotational axes among various races. The mean PCA and the W-EP angle are more externally rotated in the Indian than in the Western, population, but similar to the Chinese. Using fixed values to define the angular relationships between the axes could lead to malrotation of the femoral component. An understanding of the racial differences is essential while designing implants for the Indian population.

Outcome of Schatzker type V and VI tibial plateau fractures.

BACKGROUND: Schatzker type V and VI tibial fractures are complex injuries, usually treated with open reduction and internal fixation (ORIF) using dual plates or ring fixators. ORIF has the advantage of not requiring pin tract care, but has a higher infection rate, especially in open fractures. We have combined the advantages of these two methods to treat these difficult fractures. MATERIALS AND METHODS: Ten Schatzker type V and 11 Schatzker type VI fractures were treated between 2006 and 2010. ORIF with dual plates was performed, only if there was marked articular displacement (> 2 mm) in a closed fracture. All other fractures including open fractures and closed fractures with soft tissue compromise or minimal articular displacement were treated with ring fixators. The outcomes were analyzed and documented using the Honkonen and Jarvinen subjective, clinical, functional, and radiological criteria and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). RESULTS: Nine closed fractures with marked articular displacement (> 2 mm) were treated with dual plates. Eight closed fractures with minimal articular displacement (< 2 mm) and poor skin condition and four open fractures were treated with ring fixators. The mean follow-up period was 2 ½ years. The mean postoperative knee flexion was 128°. All patients could walk, jump, and climb steps. 90% could squat, though only 50% could duck walk properly. Radiologically, 85% had a plateau tilt of less than 5°, 92% had an articular step of less than 2 mm, and a residual articular widening of less than 5 mm. There were no major infections. Two patients had minor pin tract infections and two requested that their plates be removed subsequently. CONCLUSION: The protocol used to treat Schatzker type V and VI tibial plateau fractures has had excellent results and we suggest that all open fractures be treated with ring fixators and that ORIF should be done only for closed fractures with marked displacement.

Intra-articular ganglion cyst of the knee.

Ganglion cysts of the knee are extremely uncommon. They usually cause non-specific symptoms and do not produce classical signs. Advances in imaging techniques as well as widespread use of arthroscopy have made detection of these cysts easier, and most can be treated arthroscopically. Ganglion cysts arising within the infrapatellar fat pad are even more uncommon. We report a case of a young lady with a giant intra-articular ganglion within the infrapatellar fat pad that was treated by open excision.