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Papers by Robert Poser
The Journal of Bone and Joint Surgery-American Volume, 2000
European Journal of Trauma, 2003
Background and Purpose: Acetabular fractures with impaction/comminution of the posterior wall (AO... more Background and Purpose: Acetabular fractures with impaction/comminution of the posterior wall (AO type A1.3 c3) in older patients result in a posterior wall void > 1 cm 3 ; a collapse of the posterior wall can often be observed despite open reduction and internal fixation (ORIF) with cancellous bone grafting. Due to inferior results using ORIF in older patients (> 60 years of age), this study was initiated to assess the clinical utility of a high strength, injectable, calcium phosphate bone cement that hardens in vivo. Patients and Methods: Ten patients, all > 60 years, were treated with Norian SRS® in a prospective study and compared to a historical patient group. The posterior wall was reconstructed with plates and screws, and the large comminuted region was filled with Norian SRS® via a screw hole or small cortical gap. Results: Ten patients were treated with conventional ORIF and Norian SRS® cement. Return to normal range of motion in the Norian SRS® cement-treated patients was after 5 (range 4-6) weeks compared to 8 (6-10) weeks in the conventionally treated patients. Full weight bearing without pain occurred within 10 (8-11) weeks in the former compared to an average of 14 (12-16) weeks in the latter group. Conclusion: Poor results following posterior wall fracture of the acetabulum are due to a variety of reasons. Bone implant construct stability may be significantly enhanced by structural augmentation of regions of comprised cancellous bone. These early clinical results support previous biomechanical investigations and suggest that high-strength cements may be useful in treating these difficult acetabular fractures.
This study examined the relationship between acetabular cartilage properties after hemiarthroplas... more This study examined the relationship between acetabular cartilage properties after hemiarthroplasty surgery and surgical variables including femoral head size and position. Nineteen sheep received unilateral hip arthroplasties and were euthanized one year post-operatively to harvest the femora and acetabula. Cartilage histology, biochemistry and material properties were determined from samples located in the superior load-bearing region. Femoral head size mismatch, leg length difference, anterior-posterior and medial lateral offset and anteversion were measured. In the acetabulum. substantial cartilage degradation occurred with widespread librillation and significant changes in the biochemical and material properties compared to the intact contralateral joint. Regression analyses on the surgical variables explained 75-80% of the changes in tissue biochemistry but did not explain the material changes. Head size mismatch and leg length difference were the most significant contributors of the five variables examined and therefore may be critical to successful outcome in hemiarthroplasty.
The Journal of Bone and Joint Surgery-American Volume, 2000
European Journal of Trauma, 2003
Background and Purpose: Acetabular fractures with impaction/comminution of the posterior wall (AO... more Background and Purpose: Acetabular fractures with impaction/comminution of the posterior wall (AO type A1.3 c3) in older patients result in a posterior wall void > 1 cm 3 ; a collapse of the posterior wall can often be observed despite open reduction and internal fixation (ORIF) with cancellous bone grafting. Due to inferior results using ORIF in older patients (> 60 years of age), this study was initiated to assess the clinical utility of a high strength, injectable, calcium phosphate bone cement that hardens in vivo. Patients and Methods: Ten patients, all > 60 years, were treated with Norian SRS® in a prospective study and compared to a historical patient group. The posterior wall was reconstructed with plates and screws, and the large comminuted region was filled with Norian SRS® via a screw hole or small cortical gap. Results: Ten patients were treated with conventional ORIF and Norian SRS® cement. Return to normal range of motion in the Norian SRS® cement-treated patients was after 5 (range 4-6) weeks compared to 8 (6-10) weeks in the conventionally treated patients. Full weight bearing without pain occurred within 10 (8-11) weeks in the former compared to an average of 14 (12-16) weeks in the latter group. Conclusion: Poor results following posterior wall fracture of the acetabulum are due to a variety of reasons. Bone implant construct stability may be significantly enhanced by structural augmentation of regions of comprised cancellous bone. These early clinical results support previous biomechanical investigations and suggest that high-strength cements may be useful in treating these difficult acetabular fractures.
This study examined the relationship between acetabular cartilage properties after hemiarthroplas... more This study examined the relationship between acetabular cartilage properties after hemiarthroplasty surgery and surgical variables including femoral head size and position. Nineteen sheep received unilateral hip arthroplasties and were euthanized one year post-operatively to harvest the femora and acetabula. Cartilage histology, biochemistry and material properties were determined from samples located in the superior load-bearing region. Femoral head size mismatch, leg length difference, anterior-posterior and medial lateral offset and anteversion were measured. In the acetabulum. substantial cartilage degradation occurred with widespread librillation and significant changes in the biochemical and material properties compared to the intact contralateral joint. Regression analyses on the surgical variables explained 75-80% of the changes in tissue biochemistry but did not explain the material changes. Head size mismatch and leg length difference were the most significant contributors of the five variables examined and therefore may be critical to successful outcome in hemiarthroplasty.