A new understanding of radiographic landmarks of the greater trochanter that indicate correct femoral rotation for measurement of femoral offset.

OBJECTIVES: To establish and validate a novel method for aligning femoral rotation to accurately measure femoral offset for preoperative templating and component sizing, and to identify the physical location of two radiographic lines utilized in the described method. MATERIALS AND METHODS: Cadaveric proximal femurs were skeletonized and mounted to a biaxial load frame. Two radiographic lines along the greater trochanter were identified fluoroscopically. The femurs were rotated, and images were taken when the lines appeared superimposed, then in 2-degree increments to 10° of internal and external rotation, and at 30°. Radiographic femoral offset was calculated at each angle, and the maximum and aligned offsets were compared. Bone was removed until the radiographic lines disappeared, then a metal wire was inserted in place of the bone to confirm that the lines reappeared. RESULTS: The physical locations of the radiographic landmarks were on the anterior and posterior aspects of the greater trochanter. The mean true femoral offset was 38.2 mm (range, 30.5-46.3 mm). The mean aligned femoral offset was 37.3 mm (range, 29.3-46.3 mm), a 2.4% underestimation. The mean angle between aligned and true offset was 3.6° of external rotation (range, 10°ER-8°IR). Intra-rater intraclass correlation coefficient was 0.991. CONCLUSION: Alignment of the radiographic lines created by the anterior and posterior aspects of the greater trochanter is a reliable and accurate rotational positioning method for measuring true femoral offset when using plain films or fluoroscopy, which can aid surgeons with preoperative templating and intraoperative component placement for total hip arthroplasty.

Accuracy and Reliability of Software Navigation for Acetabular Component Placement in THA: An In Vitro Validation Study.

Background and Objectives: Intraoperative fluoroscopy can be used to increase the accuracy of the acetabular component positioning during total hip arthroplasty. However, given the three-dimensional nature of cup positioning, it can be difficult to accurately assess inclination and anteversion angles based on two-dimensional imaging. The purpose of this study is to validate a novel method for calculating the 3D orientation of the acetabular cup from 2D fluoroscopic imaging. Materials and Methods: An acetabular cup was implanted into a radio-opaque pelvis model in nine positions sequentially, and the inclination and anteversion angles were collected in each position using two methods: (1) a coordinate measurement machine (CMM) was used to establish a digitalized anatomical coordinate frame based on pelvic landmarks of the cadaveric specimen, and the 3D position of the cup was then expressed with respect to the anatomical planes; (2) AP radiographic images were collected, and a mathematical formula was utilized to calculate the 3D inclination and anteversion based on the 2D images. The results of each method were compared, and interrater and intrarater reliably of the 2D method were calculated. Results: Interrater reliability was excellent, with an interclass correlation coefficient (ICC) of 0.988 (95% CI 0.975-0.994) for anteversion and 0.997 (95% CI 0.991-0.999) for inclination, as was intrarater reliability, with an ICC of 0.995 (95% CI 0.985-0.998) for anteversion and 0.998 (95% CI 0.994-0.999) for inclination. Intermethod accuracy was excellent with an ICC of 0.986 (95% CI: 0.972-0.993) for anteversion and 0.993 (95% CI: 0.989-0.995) for inclination. The Bland-Altman limit of agreement, which represents the error between the 2D and 3D methods, was found to range between 2 to 5 degrees. Conclusions: This data validates the proposed methodology to calculate 3D anteversion and inclination angles based on 2D fluoroscopic images to within five degrees. This method can be utilized to improve acetabular component placing intraoperatively and to check component placement postoperatively.

Three-Dimensional Morphometric Characterization of Femoral Cam Lesions: Quantifying the Radial and Lateral Extents.

OBJECTIVE: To quantify the radial and lateral extents of femoral cam lesions in FAI patients relative to the alpha angle and correlate with clinical data. METHODS: Retrospective study of 81 hips with femoral cam morphology that underwent arthroscopic surgery between 2017 and 2019. At each hour over the clockface, the alpha angle (α) (abnormal defined as > 55°), radial extent, and lateral extent of cam lesions were measured on CT. These measurements were correlated with clinical and arthroscopic data. Statistics included independent samples t-test and chi-squared test with Bonferroni correction and multivariate logistic regression. RESULTS: Larger α at 12:00-4:00 in males vs females (56.6-63.4° vs 44.3-58.5°, P < 0.001) and at 2:00-4:00 with elite sports participation vs without (56.7-70.9° vs 49.6-61.1°, P ≤ 0.004). Independent risk factors for radial extent beyond 12:00-3:00 were: male sex (OR 4.82, 95% CI [1.46, 15.85], P = 0.010), BMI > 25 (OR 4.74, 95% CI [1.61, 14.00], P = 0.005), and elite sports participation (OR 3.28, 95% CI [1.09, 9.82], P = 0.034). Lateral extent increased at 1:00-4:00 in males vs females (7.8-18.6 mm vs 1.6-9.1 mm, P < 0.0001). A 16% prevalence of distal cam lesions was found at locations with normal α, resulting in underestimation of radial extent by an average of 1.7 hours. CONCLUSION: There is a positive correlation between the alpha angle, lateral extent, and radial extent of cam lesions. FAI patients who were male, participated in elite level sports, and had a BMI > 25 had larger cam lesions. A larger alpha angle is a risk factor for cartilage damage. Patients may have distal cam lesions at locations with normal alpha angles, though their significance is unknown.

Intraoperative Scrub Nurse Handoffs Are Associated With Increased Operative Times for Total Joint Arthroplasty Patients.

BACKGROUND: Surgeons typically remain scrubbed in for the duration of a surgical case, while scrub nurses are shift-workers who handoff mid-operation. These handoffs can intuitively create inefficiencies, but currently, no orthopedic research has studied the impact of these handoffs. This study analyzed the effect of intraoperative scrub nurse handoffs on operative times for total joint arthroplasties (TJAs). METHODS: A retrospective chart review was performed for primary total hip (THA) and total knee arthroplasties (TKA) performed between May 2014 and May 2018. Operative times, number of scrub nurse handoffs, surgeon, and patient information were collected. A multivariable linear regression was performed to assess the association between patient and surgeon characteristics, intraoperative handoffs, and operative times. RESULTS: A total of 1109 TKA and 1032 THA patients were identified. Multivariable linear regression demonstrated that for TKAs, 1 handoff was associated with a 3.89-minute longer operative time (P value = .02), and 2+ handoffs were associated with a 15.99-minute longer case (P value < .001). For THA patients, 1 handoff was associated with a 6.20-minute longer operative time (P value < .001), and 2+ handoffs were associated with an 18.52-minute longer case (P value < .001). CONCLUSIONS: Although causation cannot be established, when controlling for multiple confounders, intraoperative scrub nurse handoffs were associated with statistically significant increases in operative times for TJAs. Optimizing scrub nurse staffing models to decrease intraoperative handoffs could thus have practical ramifications on TJA patients.

Running with Femoral Acetabular Impingement: Operative Vs Nonoperative Treatment.

A 31-year-old female lawyer presents with right hip pain starting approximately 3 years ago and worsening over the past 2 to 3 months. She is an avid runner, running 20 to 30 miles weekly, and noticed that her pain started after a running program training for the marathon. Her pain is primarily over the lateral aspect of her hip with some radiation into the groin. The pain is made worse with impact exercises such as running and made better with walking and cycling. She has done physical therapy for the past 3 months without any significant improvement. She has not had any injections or taken anti-inflammatories because of a history of gastric ulcer disease. On physical examination she has mild tenderness over her right greater trochanter and her range of motion tests are full in terms of flexion, internal rotation, and external rotation. She has a positive FADIR (flexion-adduction-internal rotation) impingement that causes both groin and lateral hip pain. Radiograph of the right hip revealed preservation of the joint space and an anterior cam lesion with reduced offset at the femoral head neck junction. Magnetic resonance imaging (MRI) of the right hip revealed a tear at the anterior superior labrum at the 1 to 2 o'clock position along with subjacent bone marrow edema in the femoral head that is likely reactive. Computed tomography (CT) scan of the right hip confirmed a combined cam and pincer type femoral acetabular impingement of the right hip with overcoverage of the femoral head. There was 15° of femoral anteversion and the coronal lateral center of edge angle (LCEA) is 34°. Dr. Peter Moley argues that a focused rehabilitation program to restore strength and motor control of the deep hip stabilizers will provide optimal functional recovery. Dr. Jakub Tatka argues that right hip arthroscopy with labral repair and possible osteochondralplasty are indicated in order to prevent early hip arthritis and prevent long-term sequela of femoral acetabular impingement.

Multi-Site Optical Monitoring of Spinal Cord Ischemia during Spine Distraction.

Optimal surgical management of spine trauma will restore blood flow to the ischemic spinal cord. However, spine stabilization may also further exacerbate injury by inducing ischemia. Current electrophysiological technology is not capable of detecting acute changes in spinal cord blood flow or localizing ischemia. Further, alerts are delayed and unreliable. We developed an epidural optical device capable of directly measuring and immediately detecting changes in spinal cord blood flow using diffuse correlation spectroscopy (DCS). Herein we test the hypothesis that our device can continuously monitor blood flow during spine distraction. Additionally, we demonstrate the ability of our device to monitor multiple sites along the spinal cord and axially resolve changes in spinal cord blood flow. DCS-measured blood flow in the spinal cord was monitored at up to three spatial locations (cranial to, at, and caudal to the distraction site) during surgical distraction in a sheep model. Distraction was halted at 50% of baseline blood flow at the distraction site. We were able to monitor blood flow with DCS in multiple regions of the spinal cord simultaneously at ∼1 Hz. The distraction site had a greater decrement in flow than sites cranial to the injury (median -40 vs. -7%,). This pilot study demonstrated high temporal resolution and the capacity to axially resolve changes in spinal cord blood flow at and remote from the site of distraction. These early results suggest that this technology may assist in the surgical management of spine trauma and in corrective surgery of the spine.

Risk Factors and Treatment Options for Failure of a Two-Stage Exchange.

PURPOSE OF REVIEW: Although a two-stage exchange revision is reported to have a high success rate, this strategy may fail as a treatment for prosthetic joint infection (PJI). When it does, resection arthroplasty, arthrodesis, amputation, and chronic antibiotic suppression may play a role. The purpose of this review is to determine which are the main risk factors for a two-stage exchange failure and to analyze the indications and results of resection arthroplasty, arthrodesis, amputation, and antibiotic chronic suppression for PJI. RECENT FINDINGS: Recent literature demonstrates that the main risk factors for a two-stage exchange failure are as follows: hemodialysis, obesity, multiple previous procedures, diabetes mellitus, corticosteroid therapy, hypoalbuminemia, immunosuppression, rheumatological conditions, coagulation disorders, and infection due to multidrug-resistant (MDR) bacteria or fungal species. Regarding microorganisms, besides Staphylococcus aureus, Streptococcus spp., Enterobacteriaceae species such as Klebsiella pneumoniae and Enterobacter sp., Pseudomonas aeruginosa, or Acinetobacter baumannii, and fungus including Candida sp. are also considered risk factors for a two-stage exchange failure. Resection arthroplasty, arthrodesis, and amputation have a limited role. Chronic suppression is an option for high-risk patients or unfeasible reconstruction. In summary, we report the main risk factors for a two-stage exchange failure and alternative procedures when it occurs. Future research on patient-specific risk factors for a two-stage exchange may aid surgical decision-making and optimization of outcomes.