ABSTRACT
STUDY DESIGN: Cross-sectional radioanatomic study. OBJECTIVE: To introduce a classification system using MRI to describe psoas morphology and examine the position of nearby neurovascular structures. SUMMARY OF BACKGROUND DATA: Oblique lumbar interbody fusion (OLIF) and lateral lumbar interbody fusion (LLIF) offer sagittal malignment correction and reduced morbidity. LLIF has a higher incidence of nerve injuries, while OLIF has a higher incidence of vascular injuries. METHODS: Measurements were completed on the left psoas at the inferior L4 endplate. Class A was designated if the ventral border of the psoas muscle was >2 mm anterior; B if it was ≤ 2 mm anterior or posterior to the vertebral body, and C if >2 mm posterior to the vertebral body ventral border. Modified oblique corridor, measured as the distance between two lines, one at the medial border of the psoas muscle and the other at the lateral border of the nearest vascular structure, and a preferred LLIF trajectory was projected onto an axial image of the left psoas. If the trajectory violated the posterior third of the psoas, it was considered a dangerous approach due to potential iatrogenic nerve injury. RESULTS: 100 patient MRIs (Class A: 44; Class B: 27; Class C: 29) were analyzed. Average modified oblique corridor was 7.49 mm. Modified oblique corridor varied amongst the three types of psoas morphologies (A: 8.99 mm vs. B: 8.10 mm vs. C: 4.66 mm, P=0.040). LLIF trajectory intersected the 'danger zone' in 34.1%, 3.7%, and 0.0% of patients, (P<0.001) respectively. CONCLUSION: Class A psoas had the largest modified oblique corridor but highest proportion of those with a dangerous LLIF trajectory. Class C psoas had the narrowest modified oblique corridor, but no dangerous LLIF trajectories were identified.
ABSTRACT
AIMS: Earlier studies dealing with trends in the management of osteonecrosis of the femoral head (ONFH) identified an increasing rate of total hip arthroplasties (THAs) and a decreasing rate of joint-preserving procedures between 1992 and 2008. In an effort to assess new trends in the management of this condition, this study evaluated the annual trends of joint-preserving versus arthroplasties for patients aged < or > 50 years old, and the incidence of specific operative management techniques. METHODS: A total of 219,371 patients with ONFH were identified from a nationwide database between 1 January 2009 and 31 December 2015. The mean age was 54 years (18 to 90) and 105,298 (48%) were female. The diagnosis was made using International Classification of Disease, Ninth revision, Clinical Modification (ICD-9-CM) and Tenth Revision, Clinical Modification (ICD-10-CM) procedure codes. The percentage of patients managed using each procedure during each year was calculated and compared between years. The trends in the use of the types of procedure were also evaluated. RESULTS: The rate of joint-preserving procedures was significantly higher in patients aged < 50 years compared with those aged > 50 years (4.93% vs 1.52%; p < 0.001). For the overall cohort, rates of arthroplasty were far greater than those for joint-preserving procedures. THA was the most commonly performed procedure (291,114; 94.03%), while osteotomy (3,598; 1.16%), partial arthroplasty (9,171; 2.96%), core decompression (1,200; 0.39%), and bone graft (3,026; 0.98%) were performed markedly less frequently. The annual percentage of patients managed using a THA (93.56% to 89.52%; p < 0.001), resurfacing (1.22% to 0.19%; p < 0.001), and osteotomy (1.31% to 1.05%; p < 0.001) also decreased during the study period. CONCLUSION: We found that patients with ONFH have been most commonly managed with non-joint-preserving procedures. Our findings provide valuable insight into the current management of this condition and should increase efforts being made to save the hip joint. Cite this article: Bone Joint J 2020;102-B(7 Supple B):122-128.