In order to reduce the risk of dislocation larger femoral heads in total hip arthroplasty (THA) are being used by surgeons in recent years. The standard head size of 28 mm used in 73% of all hip procedures in 2003 was used in only 29% in 2016; whereas head sizes of 32 mm and 36 mm combined, were used in 70%. The increase of head size effectively reduces the thickness of the acetabular cup, altering the load transfer. Herein, this research work investigates the effect of increasing the femoral head size on the stresses of the periacetabular bone at two selected regions: A1 (superior) and A2 (anterior). Three Finite Element models were developed from CT scan data of a hemipelvis implanted with a cemented all-polyethylene acetabular cup with a 50 mm outer diameter and inner diameter to accommodate three head sizes: 28 mm, 32 mm and 36 mm. The peak reaction force at the hip joint during one leg stand for an overweight patient with a body weight of 100 Kg was simulated for head sizes investigated. We found that highest average von Mises stress was 5.7 MPa and occurred in the cortical bone of region A1 which is located within Zone 1 boundaries (Charnley &DeLee); whereas a lower stress of 4.0 MPa occurred at region A2. In the two regions the stresses were the same for the three head sizes. Periacetabular bone was found to be insensitive to the increase of femoral head diameter in cemented THA.

Objectives: tibial plateau fractures are a therapeutic challenge for the trauma surgeon. Arthroscopically assisted surgical treatment (AT) is an option in these fractures that is used more and more frequently even in more complex lesions. The objective of this study is to determine if, at a minimum 1 year follow up, arthroscopic treatment is comparable to open treatment (OT) in respect to radiologic and functional outcomes.

Materials and Methods: We have prospectively reviewed our first 50 arthroscopic cases and compared them with 50 open surgery cases examined retrospectively. The cases in the second group were selected from a database of 87 patients and were matched for Schätzker type, degree of displacement, age and sex with cases of the first group. In each group there were 50 patients (33 male/17 female; mean age: 45,4 years in the AT group and 43,6 years in the OT group). Of the 50 cases in each group, ten were Schätzker I tibial plateau fractures, sixteen were type II, seven type III, eleven type IV, three type V and three type VI. In the AT group all fractures were reduced and fixated with cannulated screws under direct arthroscopic control and in 6 cases a percutaneous plate was added. In the OT group all fractures were reduced and fixated with cannulated screws under direct vision (n=41) or radiologic control (n=9) and in 37 cases a plate was added. Associated lesions were identified and treated accordingly in both groups. Results were evaluated with the following scales: Rasmussen, Honkonen, ICDK, Lysholm, SF-36 and Knee Society scores.

Results: All cases were available for follow up a minimum of 12 months after surgery (2.6 +/−1.4 years in AT and 3.7+/−1.5 years in OC). The patients in the AT group had lower hospital stances (p< 0.05) and lesser postoperative wound complications (zero versus 3). Radiological reduction and alignment was considered excellent or good in 92% of AT cases and 88% of OT cases. Knee society scores were 191+/−18 in AT and 176+/−21 in OT. Lysholm scale scores were 85+/−20 in AT and 72+/−21 in OT. Rasmussen scale scores were 29+/−2.2 in AT and 26+/−3.9 in OT. Most of the differences between both groups was related to range of motion but pain scores were similar.

Conclusions: Arthroscopically assisted treatment of tibial plateau fractures seems to offer better results than open surgery with less hospital stay, lesser postoperative complications and clearly improved range of motion. It can be considered an adequate alternative to traditional open reduction and fixation even in complex fractures.