The Use of an External Cutting Guide for Patient-Specific Bone Grafting in Reverse Total Shoulder Arthroplasty: A Novel Technique.

Glenoid bone loss remains a substantial challenge in reverse shoulder arthroplasty and failure to address such bone loss may lead to implant malpositioning, instability and/or premature baseplate loosening. Currently, management of glenoid bone loss can be achieved by metal augmentation or bone grafting (ie, autograft or allograft). At the present time, options for creating and shaping glenoid bone grafts include free-hand techniques and simple reusable cutting guides that create the graft at a standard shape/angle. To our knowledge, there is no external guide available that enables surgeons to accurately prepare the bone graft to the desired dimensions/shape (ie, trapezoid or biplanar) to correct the glenoid deformity. In this article, we present a novel surgical technique that utilizes an external guide for creating a patient-specific bone graft to address glenoid deformity in the setting of reverse total shoulder arthroplasty.

3D Printed Patient-Specific Cutting Guides for Bone Grafting in Reverse Shoulder Arthroplasty: A Novel Technique.

Glenoid bone loss remains a challenge in shoulder arthroplasty. Addressing substantial bone loss is essential to ensure proper function and stability of the shoulder prosthesis and to prevent baseplate loosening and subsequent revision surgery. Current options for creating and shaping glenoid bone grafts include free-hand techniques and simple reusable cutting guides that cut the graft at a standard angle. There is currently no patient-specific device available that enables surgeons to accurately prepare the bone graft and correct glenoid deformity. We present a novel surgical technique using three-dimensional (3D)-printed cutting guides to create a patient-specific bone graft to address glenoid deformity in the setting of reverse shoulder arthroplasty.

A novel method for localization of the maximum glenoid bone defect during reverse shoulder arthroplasty.

BACKGROUND: Management of glenoid bone defects during reverse shoulder arthroplasty remains a challenge. The aim of our study was to preoperatively localize the maximal depth of glenoid bone defects in relation to glenoid reaming. METHODS: Thirty preoperative shoulder computed tomography scans were collected. Three assessors created standardized surgical plans, using 3-dimensional (3D) computed tomography-based Blueprint planning software in which the reaming axis was held constant at zero degrees of version and inclination. Each plan resulted in a 2-dimensional (2D) image of the reamer's contact on the glenoid and a corresponding 3D representation of the glenoid bone defect. The position of the maximum glenoid defect was localized on both the 2D and 3D images. Descriptive statistics were calculated. The correlation between angles from 2D and 3D images was assessed, and intraclass correlation was used to assess inter-rater and intrarater reliability. RESULTS: Twenty-eight patients were included. The overall mean difference between 2D and 3D angles was 5.4° (standard deviation 5.2°). The correlation between 2D and 3D angles was almost perfect. Intraclass correlation results demonstrated near-perfect agreement. The maximal glenoid defect was within 5% of a circle (or +/- 9°) from perpendicular to the high-side ream line in 85.1% of comparisons and was within 10% of a circle in 97.6% of comparisons. CONCLUSION: Using Blueprint planning software, we have demonstrated with almost perfect agreement among 3 assessors that when the reaming axis is held constant, the maximum glenoid bone defect is reliably located perpendicular to the glenoid ream line.

Indication for Computed Tomography Scan in Shoulder Instability: Sensitivity and Specificity of Standard Radiographs to Predict Bone Defects After Traumatic Anterior Glenohumeral Instability.

BACKGROUND: Quantifying glenohumeral bone loss is key in preoperative surgical planning for a successful Bankart repair. HYPOTHESIS: Simple radiographs can accurately measure bone defects in cases of recurrent shoulder instability. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A true anteroposterior (AP) view, alone and in combination with an axillary view, was used to evaluate the diagnostic properties of radiographs compared with computed tomography (CT) scan, the current gold standard, to predict significant bone defects in 70 patients. Sensitivity, specificity, and positive and negative predictive values were evaluated and compared. RESULTS: Detection of glenoid bone loss on plain film radiographs, with and without axillary view, had a sensitivity of 86% for both views and a specificity of 73% and 64% with and without the axillary view, respectively. For detection of humeral bone loss, the sensitivity was 8% and 17% and the specificity was 98% and 91% with and without the axillary view, respectively. Regular radiographs would have missed 1 instance of significant bone loss on the glenoid side and 20 on the humeral side. Interobserver reliabilities were moderate for glenoid detection (κ = 0.473-0.503) and poor for the humeral side (κ = 0.278-0.336). CONCLUSION: Regular radiographs showed suboptimal sensitivity, specificity, and reliability. Therefore, CT scan should be considered in the treatment algorithm for accurate quantification of bone loss to prevent high rates of recurrent instability.

Biomechanical evaluation of the Nice knot.

BACKGROUND: The Nice knot is a bulky double-stranded knot. Biomechanical data supporting its use as well as the number of half hitches required to ensure knot security is lacking. MATERIALS AND METHODS: Nice knots with, one, two, or three half-hitches were compared with the surgeon's and Tennessee slider knots with three half hitches. Each knot was tied 10 times around a fixed diameter using four different sutures: FiberWire (Arthrex, Naples, FL), Ultrabraid (Smith and Nephew, Andover, MA), Hi-Fi (ConMed Linvatec, Largo, FL) and Force Fiber (Teleflex Medical OEM, Gurnee, IL). Cyclic testing was performed for 10 min between 10N and 45N, resulting in approximately 1000 cycles. Displacement from an initial 10N load was recorded. Knots surviving cyclic testing were subjected to a load to failure test at a rate of 60 mm/min. Load at clinical failure: 3 mm slippage or opening of the suture loop was recorded. Bulk, mode of ultimate failure, opening of the loop past clinical failure, was also recorded. RESULTS: During cyclic testing, the Nice knots with one or more half-hitches performed the best, slipping significantly less than the surgeon's and Tennessee Slider (P < 0.002). After one half-hitch, the addition of half-hitches did not significantly improve Nice knot performance during cyclic testing (P > 0.06). The addition of half-hitches improved the strength of the Nice knot during the force to failure test, however after two half-hitches, increase of strength was not significant (P = 0.59). While FiberWire was the most bulky of the sutures tested, it also performed the best, slipping the least. CONCLUSION: The Nice knot, especially using FiberWire, is biomechanically superior to the surgeon's and Tennessee slider knots. Two half hitches are recommended to ensure adequate knot security.

Radiographic sclerotic contour loss in the identification of glenoid bone loss.

PURPOSE: Quantification of glenoid bone loss guides surgical management in the setting of anterior shoulder instability. Glenoid defects resulting in ≥20 % articular area loss require bony reconstruction. The objective of this study was to evaluate the utility of sclerotic glenoid contour loss on true anteroposterior radiography in the detection of varying quantities of simulated glenoid bone loss using a cadaveric model. METHODS: Eight cadaveric scapulae with full radiographic sclerotic contour were osteotomized to produce glenoid surface area reductions of 10-50 %. Radiography was performed initially and following each osteotomy, and assessed by an orthopedic surgeon and radiologist twice. Quantity of glenoid loss was compared using Fisher's exact test. Sensitivity, specificity, and reliability analyses were performed. RESULTS: On the first radiographic review, sclerotic contour loss was detected in 6 out of 8 scapulae with 50 % area loss, but only 1 out of 8 scapulae with 20 % area loss. There was a significantly higher proportion of radiographs containing sclerotic contour loss for defects with 50 % area loss compared to those with 0-25 % loss (p ≤ 0.02). In the detection of ≥20 % area loss, sclerotic contour loss had a sensitivity of 33-43 % and specificity of 88-100 %. Moderate inter-observer reliability (Cohen's kappa value of 0.42-0.53) and intra-observer reliability (kappa value of 0.46-0.58) were found. CONCLUSION: Radiographic sclerotic contour loss is commonly observed in radiographs of scapulae with 40-50 % glenoid area loss and less often with smaller lesions. However, this finding lacks utility in discerning specific quantifications of glenoid bone loss. In a clinical setting, sclerotic contour loss suggests the presence of a large glenoid defect that may require bony reconstruction. However, an intact sclerotic contour does not rule out significant bone loss.

Imaging methods for quantifying glenoid and Hill-Sachs bone loss in traumatic instability of the shoulder: a scoping review.

BACKGROUND: Glenohumeral instability is a common problem following traumatic anterior shoulder dislocation. Two major risk factors of recurrent instability are glenoid and Hill-Sachs bone loss. Higher failure rates of arthroscopic Bankart repairs are associated with larger degrees of bone loss; therefore it is important to accurately and reliably quantify glenohumeral bone loss pre-operatively. This may be done with radiography, CT, or MRI; however no gold standard modality or method has been determined. A scoping review of the literature was performed to identify imaging methods for quantifying glenohumeral bone loss. METHODS: The scoping review was systematic in approach using a comprehensive search strategy and standardized study selection and evaluation. MEDLINE, EMBASE, Scopus, and Web of Science were searched. Initial selection included articles from January 2000 until July 2013, and was based on the review of titles and abstracts. Articles were carried forward if either reviewer thought that the study was appropriate. Final study selection was based on full text review based on pre-specified criteria. Consensus was reached for final article inclusion through discussion amongst the investigators. One reviewer extracted data while a second reviewer independently assessed data extraction for discrepancies. RESULTS: Forty-one studies evaluating glenoid and/or Hill-Sachs bone loss were included: 32 studies evaluated glenoid bone loss while 11 studies evaluated humeral head bone loss. Radiography was useful as a screening tool but not to quantify glenoid bone loss. CT was most accurate but necessitates radiation exposure. The Pico Method and Glenoid Index method were the most accurate and reliable methods for quantifying glenoid bone loss, particularly when using three-dimensional CT (3DCT). Radiography and CT have been used to quantify Hill-Sachs bone loss, but have not been studied as extensively as glenoid bone loss. CONCLUSIONS: Radiography can be used for screening patients for significant glenoid bone loss. CT imaging, using the Glenoid Index or Pico Method, has good evidence for accurate quantification of glenoid bone loss. There is limited evidence to guide imaging of Hill-Sachs bone loss. As a consensus has not been reached, further study will help to clarify the best imaging modality and method for quantifying glenohumeral bone loss.

Locking plate fixation of proximal humeral fractures with impaction of the fracture site to restore medial column support: a biomechanical study.

BACKGROUND: Despite the advent of locking plate techniques, proximal humeral fracture fixation can fail due to varus collapse, especially in osteoporotic bone with medial cortex comminution. This study investigated the effect of restoring the integrity of the medial column by fracture impaction and shaft medialization with locking plate fixation. This construct was compared with a traditional locking plate construct under conditions of varus cyclical loading. MATERIALS AND METHODS: Proximal humeral fractures with medial comminution were simulated by performing wedge-shaped osteotomies at the surgical neck in cadaveric specimens and removing 1 cm of medial cortex. For each cadaver (n = 6), 1 humeral fracture was fixed with a traditional locking plate construct. The other was fixed with the locking plate construct plus fracture impaction and shaft medialization, resulting in medial column restoration. The humeral head was immobilized, and a repetitive, varus force was applied to the humeral shaft until construct collapse or until 25,000 cycles were completed. RESULTS: None of the constructs with fracture impaction collapsed, whereas 5 of 6 of the nonaugmented constructs collapsed before reaching 25,000 cycles (P = .008). Collapse of the 5 nonimpacted constructs that failed occurred after an average of 11,470 ± 3589 cycles. CONCLUSION: Fracture impaction increased the ability of the locking plate to withstand repetitive varus loading. This technique provides a construct biomechanically superior to locking plate fixation alone.

Proximal humeral fracture fixation: locking plate construct ± intramedullary fibular allograft.

BACKGROUND: Locking plate constructs for proximal humeral fractures can fail due to varus collapse, especially in osteoporotic bone with medial cortex comminution. Augmentation, using a fibular allograft as an intramedullary bone peg, may strengthen fixation preventing varus collapse. This study investigated the ability of the augmented locking plate construct to withstand repetitive varus stresses relative to the nonaugmented construct. MATERIALS AND METHODS: Proximal humeral fractures with medial comminution were simulated by performing wedge-shaped osteotomies at the surgical neck in cadaveric specimens. For each cadaver (n = 8), 1 humeral fracture was fixated with the locking plate construct alone and the other with the locking plate construct plus ipsilateral fibular autograft augmentation. The humeral head was immobilized and a repetitive, medially directed load was applied to the humeral shaft until construct collapse or until 25000 cycles were completed. RESULTS: No augmented construct collapsed. In comparison, 6 of 8 nonaugmented constructs collapsed (P < .05). Collapse in the 6 nonaugmented constructs occurred after an average ±SD of 6604 ± 1984 cycles. Screw penetration of the articular surface was found in only 1 of the nonaugmented constructs. CONCLUSION: Fibular allograft augmentation increased the ability of the locking plate to withstand repetitive varus loading. Clinically, this may assist proximal humeral fracture fixation in osteoporotic bone with medial cortex comminution.

Injury of the suprascapular nerve during arthroscopic repair of superior labral tears: an anatomic study.

HYPOTHESIS: The purpose of this cadaveric anatomic study was to investigate the risk of iatrogenic suprascapular nerve injury during the standard drilling techniques in arthroscopic superior labrum anterior-posterior (SLAP) repairs. MATERIALS AND METHODS: Cadaveric shoulder girdles were isolated and drilled at the glenoid peripheral rim by use of standard arthroscopic equipment reproducing common drill locations and portal orientations for SLAP repairs. Drill hole depth was determined by the manufacturer's drill stop (20 mm), and any subsequent drill perforations through the medial bony surface of the glenoid were directly confirmed by dissection. The suprascapular nerve was then isolated to note the presence of any observable direct nerve injury from the drilling. The bone tunnel depth, subsequent distance to the suprascapular nerve, scapular height and width, and humeral length were also recorded. RESULTS: Eighteen drill perforations through the medial glenoid wall occurred in 8 of 21 cadavers (38%). Twelve perforations occurred through anterosuperior drill holes with only one associated nerve injury. Six perforations occurred through low posterosuperior drill holes with four associated nerve injuries. Five of the six shoulders with low posterosuperior perforation also had an associated anterior perforation. No perforations occurred through high posterosuperior drill holes. Of the specimens, 5 had bilateral involvement (4 female and 1 male). Specimens with a perforation had a significantly shorter scapular height (P = .007) and humeral length (P = .01). CONCLUSIONS: The suprascapular nerve is at risk for direct injury during arthroscopic SLAP repairs from penetration of the medial glenoid with arthroscopic drill equipment in cadavers.