Objectives:
To determine if acromial morphology is associated with posterior or anterior shoulder instability as measured on MRI.
Methods:
MRI measurements of posterior acromial coverage (PAC), ...posterior acromial height (PAH), posterior acromial tilt (PAT), and anterior acromial coverage (AAC) were completed for three separate matched groups who underwent surgical intervention: posterior instability, anterior instability, and a comparison group of patients with who underwent arthroscopic surgery for snapping scapula. Inclusion criteria were patients with recurrent instability younger than 40 years of age without multidirectional instability, glenoid bone loss greater than 13.5% or glenoid retroversion greater than 10%.
Results:
Thirty-seven patients were included in each group. PAC was significantly less in the posterior instability group when compared to anterior and the comparison groups (68.3° vs. 88.7° vs. 81.7°, p<.001). PAH was significantly greater in the posterior group than compared to the anterior instability patients (11.0 mm vs -0.1 mm, p<.001) as well as the comparison patients (0.7 mm, p<.001). There was no difference between the posterior and anterior groups in terms of PAT or AAC (p=0.45, p=0.05). PAT was significantly smaller in the posterior instability group than the comparison group (55.2 degrees vs 62.2 degrees, p=0.026). The anterior and comparison groups were not significantly different in PAH or PAT (p=8.74, p=0.067) but were significantly different with AAC (p=0.26).
Conclusions:
The posterior acromion is significantly higher and flatter in patients with posterior shoulder instability who require arthroscopic capsulolabral repair when measured on pre-operative MRI. This information may help clinicians to both diagnose and predict the need for operative intervention for patients with posterior labral tears.
Objectives:
Dual plate fixation has been proposed as a solution to the high rates of reoperation secondary to operative management of displaced midshaft clavicle fractures. Previous studies have ...recommended dual plating for patients specifically at higher risk of reoperation. Therefore, the purpose of this study was to compare reoperation rates among patients who underwent single superior, single anterior, and dual plating while adjusting for risk factors including age, smoking status, and high-risk fracture morphology. We hypothesized lower rates of reoperation among patients who underwent dual plate fixation.
Methods:
This was a retrospective cohort study of all patients who presented with a midshaft clavicle fracture and underwent ORIF between 2007 and 2021 to our trauma/sports divisions. Patient demographics, fracture pattern, plating technique, postoperative complications, date of surgery, reoperation status, date of last follow up, and date of reoperation were documented. We report hazard ratio (HR) estimates using a multivariate multilevel mixed-effects parametric survival model, which accounted for patients with multiple reoperations and adjusted for covariates.
Results:
A cohort of 395 patients (mean age 38.5±14.4 years, 81.7% male) were identified with average follow-up of 5.5±8.6 months. There were 77 z-type, 157 transverse, and 161 oblique fractures. With regards to plating technique, 152 underwent single superior plating, 149 experienced single anterior plating, and 94 had dual plating. After initial operation, there were 8 total instances of non-union (2.0%), 0 in the dual plating cohort (0%), 4 in the superior plating cohort (2.6%), and 4 in the anterior plating cohort (2.7%) (p=0.35). A total of 28 reoperations took place among 19 patients (4.8%), with 6 patients experiencing multiple reoperations.
Single plating with superior placement revealed the highest reoperation rate of 0.26 per person-years, followed by anterior placement with 0.17 per person-years, and finally dual plating with 0.02 per person-years (Figure 1). Patients who underwent single plating (either anterior or superior placement) revealed a greater rate of reoperation when compared to patients who underwent dual plating (HR: 8.3, p=0.045). Patients who underwent single plating with superior placement had a rate of reoperation ten- times greater than patients who underwent dual plating (HR:10.1, p=0.03). Patients who underwent single plating with anterior placement had a rate of reoperation six-times greater than patients who underwent dual plating (HR: 6.4, p=0.09), although not statistically significant.
Conclusions:
Dual plate fixation of displaced midshaft clavicle fractures has an eight-fold lower risk of reoperation compared to single plate fixation, while accounting for age, smoking, and high-risk fracture morphology. More specifically, dual plating had lower rates of reoperation than both single plating with anterior and superior placement. When operative management is indicated for a midshaft clavicle fracture, dual plating may be an excellent treatment alternative in patients at high risk for reoperation.
We collected seven fixed pairs of
Rhyacophila lezeyi
during mating copulation and observed four different states of copulation. We investigated the underlying mechanism for the variations in the ...morphology of each copulating device, based on the copulation state. Notably, the male anal sclerites underwent considerable changes from the early stages of copulation. Initially, the female segment VIII approached the male anal sclerites, which were pushed downwards by the female VIII and IX segments, extending from IX. With the progression of mating stage, the distended end of the female’s segment VIII covered the anal sclerites, pushing them further down. The male parameres were initially folded in bellows-like shapes under the aedeagus before copulation initiation. However, as the copulation stage advanced, they extended to about 3.2 times of their original length. Distended ends of both parameres adhered to the position of the spiracles at the anterior margin of the lateral part of the female’s VII abdominal sternite. The attachment site was the external surface of the hair bulb of the male parameres. During the middle stage of copulation, movements involving the opening and closing of the male gonopods started. The gonoslylus made strong contact with the female’s abdominal segment VIII, resulting in the deformation of segment VIII due to the contact pressure.
Category:
Hindfoot; Sports
Introduction/Purpose:
Insertional Achilles tendinopathy (IAT) refers to calcified enlargement of the Achilles insertion. Recently, the Zadek osteotomy has been proven to be ...an effective and minimally invasive procedure for IAT with a dorsal-based closing wedge osteotomy on the posterior tuberosity of the calcaneus. However, determining the wedge size and location to determine the exact enlargement of the tuberosity remains clinically challenging. The goal of this study was to examine the morphology of the calcaneus in both normal control and IAT groups, and to propose a novel algorithm to determine the angular measurement to guide treatment with a Zadek osteotomy.
Methods:
Lateral weightbearing images of 40 control feet were used to determine the size of the calcaneus and contour of the tuberosity. The shape of the calcaneus was mapped onto part of a circle the Standard Circle (SC) whose center and radius were statistically fitted and scaled in relation to the height and width of the calcaneus. The diseased tuberosity of 40 patients with IAT was outlined and compared to their respective SC's. An angle was calculated by which the diseased calcaneus curve was rotated around the weightbearing point to fit the SC. We defined this angular measurement as the Pathologic Achilles Insertion Angle (PAIA). The size of the PAIA should be the exact size of the Zadek osteotomy if the apex of the osteotomy is chosen at the weightbearing point of the calcaneus. The effect of moving the apex of the osteotomy anteriorly on the calcaneal pitch angle was calculated.
Results:
From the morphology of the 40 normal calcanei, the equation of the Standard Curve, R^2=(x+a)^2+(y+b)^2 was created to calculate the SC. The offsets of the center of SC and the radius of SC (a, b, and R) were scaled in relation to the width and height of the calcaneus. From the morphology of the 40 enlarged tuberosities in the IAT group, an algorithm was created to automate the calculation of PAIA. This represented the extent of the enlarged Achilles insertion, which also determined the size and location of the wedge to normalize the contour of the enlarged posterior tuberosity. Using the weightbearing point of the calcaneus as the apex of the osteotomy did not change the pitch angle of the calcaneus, but moving the apex of the osteotomy anteriorly reduced the calcaneal pitch angle determined by both the original PAIA and the calcaneal pitch angle of each specific foot.
Conclusion:
Based on mechanism of mapping and curve fitting, the newly developed PAIA, will not only guide evaluation of the enlarged tuberosity in IAT, but also calculate the size of the Zadek osteotomy taking the patient's calcaneus size, IAT enlargement size, and pitch angle in consideration.
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