A Comparison of Plain Radiography with Computer Tomography in Determining Coronal and Sagittal Alignments following Total Knee Arthroplasty.

Introduction: Optimal coronal and sagittal component positioning is important in achieving a successful outcome following total knee arthroplasty (TKA). Modalities to determine post-operative alignment include plain radiography and computer tomography (CT) imaging. This study aims to determine the accuracy and reliability of plain radiographs in measuring coronal and sagittal alignment following TKA. Materials and Methods: A prospective, consecutive study of 58 patients undergoing TKA was performed comparing alignment data from plain radiographs and CT imaging. Hip-knee-angle (HKA), sagittal femoral angle (SFA) and sagittal tibial angle (STA) measurements were taken by two observers from plain radiographs and compared with CT alignment. Intra- and inter-observer correlation was calculated for each measurement. Results: Intra-observer correlation was excellent for HKA (r>0.89) with a mean difference of <1.9°. The least intra-observer correlation was for SFA (mean r=0.58) with a mean difference of 8°. Inter-observer correlation was better for HKA (r>0.95) and STA (r>0.8) compared to SFA (r=0.5). When comparing modalities (radiographs vs CT), HKA estimations for both observers showed the least maximum and mean differences while SFA observations were the least accurate. Conclusion: Radiographic estimation of HKA showed excellent intra- and inter-observer correlation and corresponds well with CT imaging. However, radiographic estimation of sagittal plane alignment was less reliably measured and correlated less with CT imaging. Plain radiography was found to be inferior to CT for estimation of biplanar prosthetic alignment following TKA.

Clinical and financial benefits of intra-articular tranexamic acid in total knee arthroplasty.

PURPOSE: To determine whether intra-articular tranexamic acid (TXA) use after total knee arthroplasty (TKA) results in decreased postoperative blood transfusion and length of hospital stay. METHODS: Medical records of 1981 patients (mean age, 69.2 years) who underwent primary TKA with (n=1006) or without (n=975) TXA use by any of 4 knee arthroplasty surgeons were reviewed. TXA (3000 mg/30ml) was administered via an epidural catheter into the knee joint after wound closure. Postoperative blood transfusion was given to patients with haemoglobin (Hb) level <80 g/dl on days 1 and 2 or with symptoms of acute anaemia. RESULTS: Intra-articular TXA use after TKA resulted in a lower blood transfusion rate (4.5% [45/1006] vs. 14.8% [144/975], p<0.0001), fewer units of blood transfused (86 vs. 313 units, p<0.0001), fewer units of blood transfused per 100 patients (8.5 vs. 32.1, p<0.0001), and shorter length of hospital stay (4.7±2.3 vs. 5.3±2.7 days, p<0.0001). Total cost savings with respect to the reduction in blood transfusion was AU$143.68 per patient. When the change in length of hospital stay and TXA costs were included, the overall saving was AU$631.36 per patient. CONCLUSION: Intra-articular TXA use can reduce costs as a result of decreased blood transfusion rate and length of hospital stay in patients undergoing TKA.

Posterior condylar cartilage thickness and posterior condylar offset of the femur: a magnetic resonance imaging study.

PURPOSE: To measure the femoral posterior condylar cartilage (PCC) thickness and the posterior condylar offset (PCO) and determine the correlation between the 2 parameters in 530 normal subjects using magnetic resonance imaging (MRI). METHODS: Records of 287 male and 243 female patients (mean age, 40.7 years) who underwent MRI for traumatic soft tissue knee injuries not involving the femoral PCC and did not have symptomatic knee arthritis were reviewed. RESULTS: The PCC thickness was comparable in the lateral and medial sides (2.04 vs. 1.99 mm, p=0.13). Males had thicker PCC in the medial (2.05 vs. 1.92 mm, p=0.0006) and lateral (2.16 vs. 1.86, p<0.0001) sides than females. Age did not correlate with PCC thickness. The bony PCO was larger in the medial than lateral side (25.8 vs. 22.6 mm, p<0.0001). Males had a larger PCO than females in the medial side only (26.1 vs. 25.5 mm, p = 0.0195). The bony PCO did not correlate with PCC thickness. CONCLUSION: Femoral PCC thickness was comparable in the medial and lateral sides. Males had thicker PCC in the medial and lateral sides than females.

Pedicle fracture after instrumented posterolateral lumbar fusion: a case report.

STUDY DESIGN: The case report of a 60-year-old man with late onset back pain after lumbar spine fusion is presented. OBJECTIVE: To report the rare complication of bilateral pedicle stress fractures after instrumented posterolateral lumbar fusion. SUMMARY OF BACKGROUND DATA: A 56-year-old man underwent revision spinal surgery for ongoing back pain secondary to pseudoarthroses. A posterolateral L4-S1 instrumented fusion using pedicle screws was performed. Autologous bone graft was applied to the decorticated lateral masses. The internal fixation was removed 2 years later, at which time plain radiographs showed that the fusion mass was solid. At the age of 60 years, the man presented with worsening back pain. Plain radiographs and computed tomographic scans demonstrated bilateral L4 pedicle stress fractures. A bone scan indicated that these were recent in origin. METHOD: The clinical assessment was undertaken by the senior author and surgeon. Investigations included plain radiography, computer tomography, and scintographic imaging. A systematic literature review of the relevant publications was performed. RESULTS: In the reported patient, bilateral pedicle stress fractures developed 2 years after pedicle screw removal from an L4-S1 instrumented posterolateral lumbar spine fusion. This occurred at the uppermost level of the fusion mass. CONCLUSIONS: The pedicle is the weakest point in the neural arch after posterolateral fusion. Although movement continues at the level of the disc space anteriorly, the pedicle is susceptible to fracture. Pedicle fracture is a rare late complication of posterolateral lumbar spine fusion.