Tibial plateau fracture reduction involves restoration of alignment and articular congruity. Restorations of sagittal alignment (tibial slope) of medial and lateral condyles of the tibial plateau are independent of each other in the fracture setting. Limited independent assessment of medial and lateral tibial plateau sagittal alignment has been performed to date. Our objective was to characterize medial and lateral tibial slopes using fluoroscopy and to correlate X-ray and CT findings. Phase One: Eight cadaveric knees were mounted in extension. C-arm fluoroscopy was used to acquire an AP image and the C-arm was adjusted in the sagittal plane from 15° of cephalad tilt to 15 ° of caudad tilt with images captured at 0.5° increments. The “perfect AP” angle, defined as the angle that most accurately profiled the articular surface, was determined for medial and lateral condyles of each tibia by five surgeons. Given that it was agreed across surgeons that more than one angle provided an adequate profile of each compartment, a range of AP angles corresponding to adequate images was recorded. Phase Two: Perfect AP angles from Phase One were projected onto sagittal CT images in Horos software in the mid-medial compartment and mid-lateral compartment to determine the precise tangent subchondral anatomic structures seen on CT to serve as dominant bony landmarks in a protocol generated for calculating medial and lateral tibial slopes on CT. Phase Three: 46 additional cadaveric knees were imaged with CT. Tibial slopes were determined in all 54 specimens. Phase One: Based on the perfect AP angle on X-ray, the mean medial slope was 4.2°+/-2.6° posterior and mean lateral slope was 5.0°+/-3.8° posterior in eight knees. A range of AP angles was noted to adequately profile each compartment in all specimens and was noted to be wider in the lateral (3.9°+/-3.8°) than medial compartment (1.8°+/-0.7° p=0.002). Phase Two: In plateaus with a concave shape, the perfect AP angle on X-ray corresponded with a line between the superiormost edges of the anterior and posterior lips of the plateau on CT. In plateaus with a flat or convex shape, the perfect AP angle aligned with a tangent to the subchondral surface extending from center to posterior plateau on CT. Phase Three: Based on the CT protocol created in Phase Two, mean medial slope (5.2°+/-2.3° posterior) was significantly less than lateral slope (7.5°+/-3.0° posterior) in 54 knees (p<0.001). In individual specimens, the difference between medial and lateral slopes was variable, ranging from 6.8° more laterally to 3.1° more medially. In a paired comparison of right and left knees from the same cadaver, no differences were noted between sides (medial p=0.43; lateral p=0.62). On average there is slightly more tibial slope in the lateral plateau than medial plateau (2° greater). However, individual patients may have substantially more lateral slope (up to 6.8°) or even more medial slope (up to 3.1°). Since tibial slope was similar between contralateral limbs, evaluating slope on the uninjured side provides a template for sagittal plane reduction of tibial plateau fractures.
The vascular anatomy of the femoral head and neck has been previously reported, with the primary blood supply attributed to the deep branch of the Medial Femoral Circumflex Artery (MFCA). This understanding has led to development of improved techniques for surgical hip dislocation for multiple intra-capsular hip procedures including Hip Resurfacing Arthroplasty (HRA). However, there is a lack of information in the literature on quantitative analysis of the contributions of the Lateral Femoral Circumflex Artery (LFCA) to femoral head and neck. Additionally, there is a lack of detailed descriptions in the literature of the anatomic course of the LFCA from its origin to its terminal branches. Twelve fresh-frozen human pelvic cadaveric specimens were studied (mean age 54.3 years, range 28–69). One hip per specimen was randomly assigned as the experimental hip, with the contralateral used as a control. Bilateral vascular dissection was performed to cannulate the MFCA and LFCA. Specimens were assigned as either LFCA-experimental or MFCA-experimental. All specimens underwent a validated quantitative-MRI protocol: 2mm slice thickness with pre- and post- MRI contrast sequences (Gd-DTPA diluted with saline at 3:1). In the LFCA-experimental group 15ml of MRI contrast solution was injected into the LFCA cannula. In the MFCA-experimental group 15ml of contrast solution was injected into the MFCA cannula. On the control hip contrast solution was injected into both MFCA and LFCA cannulas, 15ml each (30ml total for the control hip). Following MRI, the MFCA and LFCA were injected with polyurethane compound mixed with barium sulfate (barium sulfate only present in either MFCA or LFCA on each hip). Once polymerization had occurred, hips underwent thin-slice CT scan to document the extra- and intra-capsular course of the LFCA and MFCA. Gross dissection was performed to visually assess all intra-capsular branches of both the MFCA and LFCA and assess for extravasation. Quantitative-MRI analysis was performed based on Region of Interest (ROI) assessment. Femoral heads were osteotomized at the level of the largest diameter proximal to the articular margin and perpendicular to the femoral neck, for placement of a 360° scale. Measurements using the 360° scale were recorded. For data processing, we used right-side equivalents and integrated our 360° data into the more commonly used imaginary clock face.Introduction
Materials & Methods
A surgical hip dislocation provides circumferential access to the femoral head and is essential in the treatment pediatric and adult hip disease. Iatrogenic injury to the femoral head blood supply during a surgical may result in the osteonecrosis of the femoral head. In order to reduce vessel injury and incidence of AVN, the Greater Trochanteric Osteotomy (GTO) was developed and popularized by Ganz. The downside of this approach is the increased morbidity associated with the GTO including non-union in 8% and painful hardware requiring removal in 20% of patients. (reference) Recent studies performed at our institution have mapped the extra-osseous course of the medial femoral circumflex artery and provide surgical guidelines for a vessel preserving posterolateral approach. In this cadaveric model using Gadolinium enhanced MRI, we investigate whether standardized alterations in the postero-lateral surgical approach may reliably preserve femoral head vascularity during a posterior surgical hip dislocation In 8 cadaveric specimens the senior author (ES) performed a surgical hip dislocation through the posterolateral approach with surgical modifications designed to protect the superior and inferior retinacular arteries. In every specimen the same surgical alterations were made using a ruler: the Quadratus Femoris myotomy occurred 2.5 cm off its trochanteric insertion, the piriformis tenotomy occurred at its insertion and extended obliquely leaving a 2 cm cuff of conjoin tendon (inferior gemellus), and the Obturator Externus (OE) was myotomized 2 cm off its trochanteric insertion. (Figure 1) For the capsulotomy, the incision started on the posterior femoral neck directly beneath the cut obturator externus tendon and extending posteriorly to the acetabulum. Superior and inferior extensions of the capsulotomy ran parallel to the acetabular rim creating a T-shaped capsulotomy. After the surgical dislocation was complete, the medial femoral circumflex artery (MFCA) was cannulated and Gadolinium-enhanced MRI performed in order to assess intra-osseous femoral head perfusion and compared to the gadolinium femoral head perfusion of the contra-lateral hip as a non-operative control. Gross-dissection after polyurethane latex injection in the cannulated MFCA was performed to validate MRI findings and to assess for vessel integrity after the surgical dislocation.Introduction:
Methods:
Successful total joint arthroplasty requires accruate and reproducible acetabular component position. Acetabular component malposition has been associated with complications inlcuding dislocation, implant loosening, and increased wear. Recent literature had demonstrated that high-volume fellowship trained arthroplasty surgeons are in the “safe zone” for cup inclination and anteversion only 47% of the time. (1) Computer navigation has improved accuracy and reproducibility but remains expensive and cumbersome to many hospital and physicians. Patient specific instrumentation (PSI) has been shown to be effective and efficient in total knee replacements. The purpose of this study was to determine in a cadaveric model the anteversion and inclination accuracy of acetabular guides compared to a pre-operitive plan. 8 fresh-frozen cadaveric pelvis specimens underwent Computer Tomography (CT) in order to create a 3D reconstruction of the acetabulum. Based on these 3D reconstruction, a pre-operative plan was made positioning the patient specific acetabulum guides at 40 degrees of inclination and 20 degrees of anteversion in the pelvis.(Figure 1) The guides were created based on the specific bony morphology of the acetabular notch and rim. The guides were created using a 3D printer which allowed for precise recreation of the virtual model. 7 cadaveric specimens underwent creation and implantation of a acetabular guide specific to each specimens bony morphology. Ligamentum, pulvinar, and labum were removed for each cadaver prior to implantation to prevent soft tissue obstruction. The guides were inserted into the acetabular notch with the final position based on the fit of the guide in the notch. (Figure 2) Post-implantation CT was then performed and inclination and anteversion of the implanted guide measured and compared to the preoperative plan.Introduction:
Methods:
Precise knowledge of the Femoral Head (FH) arterial supply is critical to avoid FH avascular necrosis following open and arthroscopic intra-capsular surgical procedures about the hip. The Medial Femoral Circumflex Artery (MFCA) provides the primary FH vascular contribution. Distribution of vascular foramina at the Femoral Head-Neck Junction (FHNJ) has been reported previously using an imaginary clock face. However, no quantitative information exists on the precise Capsular Insertion (CI) and intra-capsular course of the MFCA Terminal Branches (TBs) supplying the FH. This study seeks to determine the precise anatomic location of the MFCA's TBs supplying the FH, in order to help avoid iatrogenic vascular damage during surgical intervention. In 14 fresh-frozen cadaveric hips (9 left and 5 right), we cannulated the MFCA and injected a polyurethane compound. Using a posterior approach, careful dissection of the MFCA allowed us to identify and document the extra- and intra-capsular course of the TBs penetrating the FHNJ and supplying the FH. An H-type capsulotomy provided joint access while preserving the intracapsular Retinaculum of Weitbrecht (RW), followed by circumferential capsulotomy at the acetabular margin exposing the FH. The dome of the FH was osteotomized 5 mm proximal to the Articular Border (AB) providing a flat surface for our 360° scale. Right-side equivalents were used for data processing.Introduction
Methods
The debate regarding the importance of preserving the blood supply to the femoral head (FH) and neck during hip resurfacing arthroplasty (HRA) is ongoing. Several surgeons continue to advocate for the preservation of the blood supply to the resurfaced heads for both the current HRA techniques and more biologic approaches for FH resurfacing. Despite alternative blood-preserving approaches for HRA, many surgeons continue to use the posterior approach (PA) due to personal preference and comfort. It is commonly accepted that the PA inevitably damages the deep branch of the medial femoral circumflex artery (MFCA). This study seeks to evaluate and measure the anatomical course of the ascending and deep branch of the MFCA to better describe the area in danger during the posterior approach. In 20 fresh-frozen cadaveric hips, we cannulated the MFCA and injected a urethane compound. The Kocher-Langenbeck approach was used in all specimens. The deep branch of the MFCA was identified at the proximal border of the QF and measurements were taken. The QF was incised medially and elevated laterally, maintaining the relationship of the ascending branch and QF, and distances from the lesser trochanter were measured. The deep branch was dissected and followed to its capsular insertion to assess the course and relation to the obturatur externus (OE) tendon and the conjoint tendon (CT) of the short external rotators.Introduction
Methods
