Deltoid Origin Research Articles

Anatomic variations of the deltoid muscle insertion: a cadaveric study

The deltoid is a trisegmented muscle with anterior, middle, and posterior components. While the clinical relevance of the presence of anatomic variations of the deltoid origin and insertion continues to be debated, the architecture of the deltoid muscle is more complex than initially believed. This study aimed to evaluate the gross anatomy of the deltoid muscle insertion by qualitatively and quantitatively characterizing the insertion and location of the deltoid muscle's anterior, middle, and posterior components. This information is valuable to surgeons as it raises awareness of potential variants that could be encountered during surgery, promotes mindfulness of neurovascular proximities, and reduces the likelihood of confusion between adjacent muscle fibers. Eight nonpaired, fresh-frozen clavicle-to-fingertip cadaveric shoulders were acquired for the study (6 left, 2 right). The average age of the cadavers was 79.5 years (range: 64-92). The standard deltopectoral approach was carried out on all specimens. The planes dividing the anterior, middle, and posterior deltoid were identified and marked. Once complete exposure had been achieved, digital calipers were used to record the size of the deltoid insertion. The specimens were qualitatively assessed to characterize the style of insertion they demonstrated. The average length of the deltoid insertion was 39.45±9.33 mm (n=8). Six of the eight shoulders demonstrated an insertion style previously characterized in the literature. The remaining two shoulders highlighted an insertion pattern not previously described. The current study demonstrates a novel insertion pattern for the deltoid muscle that has not been previously characterized. This "step-off" insertion pattern shows that the anterior, middle, and posterior tendons are inserted superior-medial, directly on, and inferior-lateral to the deltoid tuberosity and was found in 2/8 of our cadaveric specimens.

Influence of Critical Shoulder Angle and Rotator Cuff Tear Type on Load‐Induced Glenohumeral Biomechanics: A Sawbone Simulator Study

Glenohumeral (GH) biomechanics after rotator cuff (RC) tears are not fully understood. The purpose of our study was to determine if the critical shoulder angle (CSA), type of RC tears, and level of weight bearing increase GH translation, instability based on the instability ratio, muscle forces and joint reaction force (JRF), and shifts the center of force (CoF) superiorly. A GH simulator with muscle‐mimicking cable systems was used to simulate 30° abduction in the scapular plane. A Sawbone humerus and five specimen‐specific scapular anthropometries were used to test six types of RC tears, three weight‐bearing loads, and the native and adjusted (to different CSAs) deltoid origin sites. Linear mixed effects models (CSA, RC tear type, and weight bearing) with random effects (specimen and sex) were used to assess differences in GH biomechanics. With increasing CSA, GH translation increased, JRF decreased, and the CoF position was more inferior. RC tears did not significantly alter GH translation but shifted the CoF position superiorly, close to where glenoid erosion occurs in patients with RC tears with secondary osteoarthritis. Weight bearing significantly increased GH translation and JRF. RC and deltoid muscle forces increased with the presence of RC tears and increased weight bearing. The remaining RC muscles of intact tendons compensated for the torn RC tendons but not for the altered CoF position. GH translation remained comparable to shoulders with intact RC. These findings highlight the importance of early detection, clinical management, and targeted rehabilitation strategies for patients with RC tears.

Deltoid-Sparing Modified Judet Approach: Technique and Clinical Series

Posterior approaches provide the mainstay for treatment in most of the scapula body and neck fractures, even those associated with many intraarticular variants. Several posterior approach modifications for minimizing soft-tissue damage and limiting muscular detachment, have previously been described in the literature; however, little or no clinical evidence is available specifically applied to the various approaches.In this study, we describe complete sparing of the deltoid muscle origin during the "modified Judet" approach. The modified approach as previously described detaches the deltoid origin. Deltoid sparing allows for satisfactory visualization and fixation of extra-articular scapula fractures and even some intraarticular variants. The purpose of this article was to describe the deltoid-sparing modified Judet approach and report clinical outcomes for 23 patients after surgical treatment.

Allograft-enhanced latissimus dorsi transfer is better than the conventional technique for irreparable posterosuperior rotator cuff tears. A retrospective matched cohort.

Latissimus dorsi tendon (LDT) transfer (LDTT) to the greater tuberosity to treat irreparable posterosuperior rotator cuff tears (RCTs) in young active patients has been shown to have up to 36% of clinical failures, most of them happening because of either deltoid origin disruption or post-operative transfer rupture from the greater tuberosity. In an attempt to simultaneously prevent both complications, a modified technique includes the following adaptations to the original technique: reinforcement and augmentation of the LDT with a tendinous allograft, enabling the use of a single deltopectoral approach. The aim of this study is to compare mid-term outcomes of the traditional LDTT technique with this modified transfer. Retrospective cohort study comparing two groups who underwent either the traditional (group 1; n = 19) or the modified technique (group 2; n = 27). Group homogenization was assured by statistical comparison of 24 baseline independent variables. The outcome variables were the gains to active shoulder range of motions (ROM) and UCLA scores (and all its subscores, independently), at a minimum follow-up of two years. A p value < .05 was considered to be statistically significant. At a mean follow-up of 25months, both groups have shown improvements to most variables. However, group two (modified technique) achieved greater improvements to UCLA score (p = .009), active external rotation (p = .006) and internal rotation (p = .008). At mid-term follow-up, improvements to outcomes of the modified (single approach, allograft-enhanced) latissimus dorsi transfer were greater than those of the original technique.

The anterior head of deltoid in relation to anterior clavicle plating: how much are we releasing?

Six right and 4 left cadaver shoulders were dissected, each from separate cadaveric specimens (6 male and 4 female). All measurements were made with digital calipers. The length of the clavicle was measured from the acromioclavicular joint to the sternoclavicular joint. The length of deltoid origin on the lateral clavicle was measured from the acromioclavicular joint to the most medial attachment of the deltoid on the clavicle. Percentage of clavicle with deltoid origin was subsequently calculated. The average length of the cadaveric clavicles was 164.4 mm with a range from 134.3 to 178.1 mm. The average amount of deltoid origin on the clavicle was 58.7 mm with a range from 43.4 to 69 mm. On average 35.5% of the clavicle had deltoid origin, with a range from 30.2% to 38.8%. On average, 35.5% of the clavicular osseous anatomy contains deltoid origin. This should be taken into consideration when performing anterior plating for clavicle fractures. With a significant portion of deltoid origin elevated, surgeons may consider altering postoperative protocols until some interval healing has occurred to this anterior head of the deltoid.

Three-Dimensional Footprint Mapping of the Deltoid and Trapezius: Anatomic Pearls for Acromioclavicular Joint Reconstruction

To perform a quantitative anatomic evaluation of the deltoid and trapezius footprints in relation to the lateral clavicle and acromioclavicular (AC) joint capsule to assist in surgical technique of AC joint reconstructions. Fourteen fresh-frozen human cadaveric shoulders from 9 donors were analyzed. Meticulous dissection of the deltoid origin and trapezius insertions to the clavicle and AC joint was performed. Footprints were reconstructed using a MicroScribe digitizer. The inferior extension of the deltoid origin beneath the lateral clavicle and the footprints of the deltoid and trapezius onto the acromioclavicular ligamentous complex (ACLC) were quantified. Reproducibility was assessed by redigitizing 5 shoulders in a blinded and random fashion. The anterior deltoid fibers extended on average 4.0 ± 1.6 mm inferiorly with respect to the anteroinferior clavicular ridge and attached to 90.9 ± 7.3% of the anterior ACLC. The trapezius inserted onto the posterior and superior ACLC, covering 15.3 ± 3.4% of the anterior-posterior width of the superior capsule. The deltopectoral interval was 6 cm, or 37% the length of the clavicle from the distal end of the clavicle. The deltoid has superior, anterior, and not as well described, inferior attachments to the lateral clavicle. Furthermore, the deltoid and trapezius muscles have intimate attachments to the AC joint capsule, particularly the trapezius to the posterior and posterosuperior capsule. Lastly, the deltoid origin attaches to the lateral 6 cm of the clavicle. Subperiosteal elevation of the deltoid off the lateral clavicle starting superiorly, anteriorly, and lastly inferiorly will reduce deltoid muscle injury and improve visibility of the coracoid process during reconstruction. Furthermore, knowledge of the attachments of the deltoid and trapezius to the ACLC may help limit iatrogenic injury to these dynamic stabilizers.

No difference in long-term outcome between open and arthroscopic rotator cuff repair: a prospective, randomized study

BackgroundArthroscopic rotator cuff repair techniques have almost replaced open repairs. Short- and mid-term studies have shown comparable outcomes, with no clear superiority of either procedure. The aim of this study was to compare the long-term clinical and imaging outcomes following arthroscopic or open rotator cuff repair.MethodsForty patients with magnetic resonance imaging (MRI)–documented, symptomatic supraspinatus or supraspinatus and infraspinatus tears were randomized to undergo arthroscopic or open rotator cuff repair. Clinical and radiographic follow-up was obtained at 6 weeks, 3 months, 1 year, 2 years, and >10 years postoperatively. Clinical assessment included measurement of active range of motion, visual analog scale score for pain, functional scoring according to the Constant-Murley score (CS), and assessment of the Subjective Shoulder Value. Imaging included conventional radiography and MRI for the assessment of cuff integrity and alteration of the deltoid muscle.ResultsWe enrolled 20 patients with a mean age of 60 years (range, 50-71 years; standard deviation [SD], 6 years) in the arthroscopic surgery group and 20 patients with a mean age of 55 years (range, 39-67 years; SD, 8 years) in the open surgery group. More than 10 years’ follow-up was available for 13 patients in the arthroscopic surgery group and 11 patients in the open surgery group, with mean follow-up periods of 13.8 years (range, 11.9-15.2 years; SD, 1.1 years) and 13.1 years (range, 11.7-15 years; SD, 1.1 years), respectively. No statistically significant differences in clinical outcomes were identified between the 2 groups: The median absolute CS was 79 points (range, 14-84 points) in the arthroscopic surgery group and 84 points (range, 56-90 points) in the open surgery group (P = .177). The median relative CS was 94% (range, 20%-99%) and 96% (range, 65%-111%), respectively (P = .429). The median Subjective Shoulder Value was 93% (range, 20%-100%) and 93% (range, 10%-100%), respectively (P = .976). MRI evaluation showed a retear rate of 30% equally distributed between the 2 groups. Neither fatty infiltration of the deltoid muscle, deltoid muscle volume, nor the deltoid origin were different between the 2 groups.ConclusionIn a small cohort of patients, we could not document any difference in clinical and radiographic outcomes at long-term follow-up between arthroscopic and open rotator cuff repair. The postulated harm to the deltoid muscle with the open technique could not be confirmed.

The Lateral Deltoid Originates From the Entire Lateral Wall of the Acromion: MRI and Histologic Cadaveric Analysis Regarding Vertical Lateral Acromioplasty

PurposeThe aim of this study was to assess the nature of the middle deltoid muscle insertion onto the lateral acromion by macroscopic, MRI and histologic examination and to, therefore, assess the potential impact of a vertical lateral acromioplasty on the deltoid origin.MethodsWe assessed the acromial origin of the deltoid in 6 cadaver shoulders by macroscopic, MRI and histologic examination. The cadavers were scanned with T1 and proton density-weighted sequences. H&E- and Masson trichrome-stained histologic sections through the acromion were taken and visualized under polarized microscopy.ResultsThe enthesis of the deltoid muscle consisted of dense birefringent bundles of collagen that blended with the bony endplate of the acromion at all points on its lateral wall. A prominent band of collagen was seen on both MRI and histologic slices, traversing the superior surface of the acromion. It was continuous with the deltoid origin and blended with the superficial fascia of the deltoid laterally.ConclusionsThe middle deltoid muscle occupies the entire lateral acromion.Clinical RelevanceA high critical shoulder angle is associated with rotator cuff tears. A lateral acromioplasty resects the lateral acromion and aims to normalize the critical shoulder angle. However, a vertical lateral acromioplasty may release the middle deltoid origin from the lateral acromion. The superior band of collagen may anchor the middle deltoid to the superior acromion and prevent retraction.

Lateral acromioplasty for correction of the critical shoulder angle

AbstractThe critical shoulder angle (CSA) was introduced as a radiological parameter associated with a higher incidence of rotator cuff tears. As a logical consequence, correcting the CSA together with rotator cuff repair should prevent re-tear and provide reliable and good clinical results. We present an all-arthroscopic technique resecting the lateral edge of the acromion (lateral acromioplasty) in order to reduce and correct the CSA after preoperative planning. Preliminary results from 20 patients with an average age of 62 years after rotator cuff repair are reported showing good clinical outcome with a Constant score of 88 points and no re-tear after an average follow-up of 16 months. The CSA was reduced from 39.7° to 32.1°. Previous concerns regarding weakening of the deltoid origin were not confirmed and there were no complications linked to lateral acromioplasty.

Clinical and Imaging Outcomes After Revision Open Rotator Cuff Repair: A Retrospective Review of a Midterm Follow-Up Study.

Revision open rotator cuff repair (ORCR) has been associated with unpredictable functional outcome with concerns of deltoid detachment. The aim of this study was to evaluate the clinical and imaging outcomes of revision ORCR. The study retrospectively reviewed 30 consecutive patients (mean age 60.4 ± 7.2years) who underwent revision ORCR after failed rotator cuff repair. Pain visual analog scale (VAS), Constant and American Shoulder Elbow Surgeon (ASES) score were assessed preoperatively and at mean 58-month follow-up (range 24-120months). The acromio-humeral distance (AHD) was measured on pre- and postoperative radiograph. Tear size and fatty infiltration of rotator cuff were evaluated by preoperative magnetic resonance imaging (MRI) study. The retear rate, change of fatty infiltration and deltoid origin integrity were evaluated by postoperative MRI. There was significant improvement of pain VAS and functional outcome scores (all p < 0.001). AHD showed no significant change after surgery. On postoperative MRI, the retear rate was 43% (13/30). However, the size of the tendon defect was smaller than that of pre-revision tear (p = 0.006). The patients who had intact tendon had significantly better functional outcomes than those with retear. The intact group had significantly higher AHD both pre- and postoperatively than the retear group. There was no change of fatty infiltration after surgery. Four patients (13%, 4/30) showed thinning of deltoid origin on postoperative MRI, but showed no weakness on clinical examination. Revision ORCR resulted in improved outcomes in pain relief and shoulder function, with low rate of subclinical deltoid thinning.

Evaluation of Deltoid Origin Status Following Open and Arthroscopic Repair of Large Rotator Cuff Tears: A Propensity-Matched Case-Control Study.

BackgroundThe purpose of this study was to evaluate and compare deltoid origin status following large rotator cuff repair carried out using either an open or an arthroscopic method with a propensity score matching technique.MethodsA retrospective review of 112 patients treated for full-thickness, large rotator cuff tear via either a classic open repair (open group) or an arthroscopic repair (arthroscopic group) was conducted. All patients included in the study had undergone postoperative magnetic resonance imaging (MRI) and clinical follow-up for at least 12 and 18 months after surgery, respectively. Propensity score matching was used to select controls matched for age, sex, body mass index, and affected site. There were 56 patients in each group, with a mean age of 63.3 years (range, 50–77 years). The postoperative functional and radiologic outcomes for both groups were compared. Radiologic evaluation for postoperative rotator cuff integrity and deltoid origin status was performed with 3-Tesla MRI.ResultsThe deltoid origin thickness was significantly greater in the arthroscopic group when measured at the anterior acromion (P=0.006), anterior third (P=0.005), and middle third of the lateral border of the acromion level (P=0.005). The deltoid origin thickness at the posterior third of the lateral acromion was not significantly different between the arthroscopic and open groups. The arthroscopic group had significantly higher intact deltoid integrity with less scarring (P=0.04). There were no full-thickness deltoid tears in either the open or arthroscopic group.ConclusionsOpen rotator cuff repair resulted in a thinner deltoid origin, especially from the anterior acromion to the middle third of the lateral border of the acromion, at the 1-year postoperative MRI evaluation. Meticulous reattachment of the deltoid origin is as essential as rotator cuff repair when an open approach is selected.

Open Rotator Cuff Repair: Where Does it Stand Now?

Introduction:With recent improvements to arthroscopic techniques, surgery for rotator cuff tears (RCT) has shifted from open repair to all-arthroscopic repair. Although evidence has not supported improved outcomes with arthroscopic techniques over the open rotator cuff repair, but as expected the incidence of performing open rotator cuff repair decrease from 43.1 to 24.9% from the last decade (USA).1 The all-arthroscopic technique is preferable among shoulder surgeons and has been accepted as the gold standard for the repair of RCT because this approach is minimally invasive and causes less insult to the deltoid muscle, which are believed to reduce postoperative infection and favour rehabilitation. 2, 3 Despite the switch towards all-arthroscopic RCR, open repair is still performed with reliable clinical outcome. In some country setting, the main reason to favor open repair is because of the high cost – utility ratio in which arises from the consumables arthroscopic tools and implants. The second reason is massive retracted RCT or in the case for revision rotator cuff surgery in which non prosthetic arthroplasty is required. We investigated the merit of open versus arthroscopic RCR for large RCT by comparison of the clinical and radiological outcome with propensity matching score technique.Methods:The outcomes of 112 patients who were treated for large, full-thickness, RCT either by open repair or arthroscopic repair were retrospectively reviewed. All patients included in this study were followed-up for at least 18 months and were imaged at a minimum of 12 months after surgery. Propensity score matching was used to select for controls matched by age, sex, body mass index and affected site. The post-operative functional and radiologic outcomes were compared. Radiologic evaluations were performed using 3 T MRI for (1) post-operative rotator cuff integrity, (2) deltoid origin status and, (3) regional acromio-humeral distance which measured at 3 regions of interests of the lateral acromion border (anterior third, middle third and posterior third).Results:The range of motion, muscle strength and functional scores improved postoperatively for both groups. Open group showed higher constant (p=0.012) and ASES score (p=0.047). Arthroscopic group showed better forward elevation (p=0.006) and external rotation (p=0.004) with less postoperative pain compared to open group (p<0.001). Operative time and hospitalization stay were shorter in arthroscopic group (p=0.007 and p<0.001). Re-tear rate was higher in arthroscopic group (25%) than open group (17.9%) without statistical difference (p=0.300).The deltoid origin thickness was significantly greater in the arthroscopic group when measured at the anterior acromion as well as the anterior third and middle third of the lateral border of the acromion. There was no significant difference in deltoid origin thickness at the posterior third of the lateral acromion between groups. Deltoid integrity was significantly better with less scaring in the arthroscopic group. There was no full-thickness deltoid tear in either group.AHD was significantly greater in open group when measured at the anterior third of the lateral acromion border compare to arthroscopic group (p=0.005). Re-tear rate was affected by AHD at the anterior third of lateral border of acromion for arthroscopic and open group (p=0.021, p=0.029). Re-tear rate was affected by AHD at middle third of lateral border of acromion for open group (p=0.046).Conclusions:Open rotator cuff is still warranted at the present day. Both repair technique showed comparable outcome for large size RCT. Open repair has superior functional score with lower re-tear rate while arthroscopic repair has superior ROM improvement, pain relief, shorter operation and hospitalization time. Imaging confirmed that open repair of RCT resulted in less thickness of the deltoid origin, especially at the anterior acromion to the middle third of the lateral acromion border at 12 months after surgery. Careful re-attachment of the deltoid origin is essential for open repair of RCT. Open RCR showed greater AHD at the anterior third of the lateral border of acromion. Regional AHD measured at anterior third of the lateral border of acromion significantly associated with re-tear rate following both open and arthroscopic RCR. Nevertheless, regional AHD measured at middle third of the lateral border of acromion significantly associated only with re-tear rate following open RCR.References Day MA, Westermann RW, Bedard NA, et al. Trends Associated with Open Versus Arthroscopic Rotator Cuff Repair. HSS J 2019; 15: 133-136. 2019/07/23. DOI: 10.1007/s11420-018-9628-2.Snyder SJ. Evaluation and treatment of the rotator cuff. Orthop Clin North Am 1993; 24: 173-192. 1993/01/01.Gartsman GM, Khan M and Hammerman SM. Arthroscopic repair of full-thickness tears of the rotator cuff. J Bone Joint Surg Am 1998; 80: 832-840. 1998/07/09.

Options of bipolar muscle transfers to restore deltoid function: an anatomical study

To outline the technical details and determine the ranges of two pedicled functioning flaps that are the upper pectoralis major (UPM) and latissimus dorsi (LD) to elucidate their respective indications with regards to deltoid impairment. The UPM and LD bipolar transfers were performed in 14 paired cadaveric shoulders, one on each side. The UPM was flipped 180° laterally over its pedicle to be placed onto the anterior deltoid. The LD flap was elevated on its pedicle to be rotated and positioned onto the deltoid mid-axis. Their respective spans were defined according to the deltoid muscle origin and insertion. The UPM outreached the lateral edge of the anterior deltoid origin with a mean distance of 7.3cm (range 4-9.1cm) off the lateral edge of the clavicle. Distally, the flap consistently overcame the proximal end of the deltoid tuberosity for a mean distance of 2.1cm (range 0.9-3.2cm). The LD flap mdi-axis could be consistently placed onto the deltoid mid-axis; spans of the anterior and posterior borders of the LD flap averaged 1cm (range - 1 to 2.3cm) and 0.2cm (range -1.8 to 1.9cm), respectively. The UPM flap optimal indications would be cases with deltoid defects limited to its anterior portion, whereas the LD bipolar transfer could be used in more extensive lesions. Additionally, the distal span of both transfers appears to allow their use in the setting of a reverse shoulder arthroplasty with subsequent humeral lengthening. Non-applicable-basic science study, cadaver dissection.

The lever arm ratio of the rotator cuff to deltoid muscle explains and predicts pseudoparalysis of the shoulder: the Shoulder Abduction Moment index.

In patients with a rotator cuff tear, tear pattern and tendon involvement are known risk factors for the development of pseudoparalysis of the shoulder. It remains unclear, however, why similar tears often have very different functional consequences. The present study hypothesizes that individual shoulder anatomy, specifically the moment arms (MAs) of the rotator cuff (RC) and the deltoid muscle, as well as their relative recruitment during shoulder abduction, plays a central role in pseudoparalysis. Biomechanical and clinical analyses of the pseudoparalytic shoulder were conducted based on the ratio of the RC/deltoid MAs, which were used to define a novel anatomical descriptor called the Shoulder Abduction Moment (SAM) index. The SAM index is the ratio of the radii of two concentric spheres based on the centre of rotation of the joint. One sphere captures the humeral head (numerator) and the other the deltoid origin of the acromion (denominator). A computational rigid body simulation was used to establish the functional link between the SAM index and a potential predisposition for pseudoparalysis. A retrospective radiological validation study based on these measures was also undertaken using two cohorts with and without pseudoparalysis and massive RC tears. Decreased RC activity and improved glenohumeral stability was predicted by simulations of SAM indices with larger diameters of the humeral head, being consequently beneficial for joint stability. Clinical investigation of the SAM index showed significant risk of pseudoparalysis in patients with massive tears and a SAM < 0.77 (odds ratio (OR) 11). The SAM index, which represents individual biomechanical characteristics of shoulder morphology, plays a determinant role in the presence or absence of pseudoparalysis in shoulders with massive RC tears.

Arthroscopic Correction of the Critical Shoulder Angle Through Lateral Acromioplasty: A Safe Adjunct to Rotator Cuff Repair

To investigate whether arthroscopic lateral acromioplasty reliably decreases the critical shoulder angle (CSA) and whether it is associated with damage to the deltoid or other complications. Patients undergoing arthroscopic rotator cuff repair (RCR) with lateral but without anterior acromioplasty for degenerative, full-thickness rotator cuff tears and a CSA of 34° or greater were retrospectively reviewed. Patients with traumatic or irreparable rotator cuff tears, osteoarthritis, or previous surgery were excluded. Clinical and radiographic outcomes were assessed at a minimum of 12months' follow-up. We reviewed 49 consecutive patients (mean age, 56years; age range, 39-76years) at a mean of 30months (range, 12-47months). There were 7 RCR failures (14%). The mean CSA was reduced from 37.5° preoperatively (95% confidence interval [CI], 36.7°-38.3°) to 33.9° postoperatively (95% CI, 33.3°-34.6°; P < .001). There were no cases of dehiscence, increases in fatty infiltration, or significant atrophy of the deltoid. Scarring at the deltoid origin was noted in 18 patients (37%). The mean absolute and relative Constant scores increased from 59 points (95% CI, 54-64 points) to 74 points (95% CI, 70-78 points) and from 66% (95% CI, 61%-71%) to 83% (95% CI, 79%-87%) respectively, and the Subjective Shoulder Value increased from 45% (95% CI, 39%-50%) to 80% (95% CI, 74%-86%) (P< .001 for all 3 improvements). The postoperative CSA was significantly larger in failed than in healed repairs (P= .026). Patients with a healed RCR and a CSA corrected to 33° or less (n= 22) had 25% more abduction strength than patients with a healed cuff and a CSA corrected to 35° or greater (n= 14, P= .04). Arthroscopic lateral acromioplasty performed in addition to arthroscopic RCR can reduce the CSA without significantly compromising the deltoid origin, deltoid muscle, or function. It is not associated with any additional complications of arthroscopic RCR. Insufficiently corrected, abnormally large CSAs are associated either with a higher retear rate or with inferior strength of abduction if the tears heal. Level IV, case series, treatment study.

Impact of Arthroscopic Lateral Acromioplasty on the Mechanical and Structural Integrity of the Lateral Deltoid Origin: A Cadaveric Study

To determine whether a 5-mm and/or 10-mm arthroscopic lateral acromioplasty (ALA) would weaken the structural and mechanical integrity of the lateral deltoid. The acromion and lateral deltoid origin were harvested from 15 pairs (n= 30) of fresh-frozen human cadaveric shoulder specimens. One side of each specimen pair (left or right) was randomly assigned to either a 5-mm (n= 7) or 10-mm (n= 8) ALA group, and the contralateral sides (n= 15) were used as matched controls. Acromion thickness and width were measured pre- and postoperatively. After ALA, specimens were inspected for damage to the lateral deltoid origin. Each specimen was secured within a dynamic testing machine, and the deltoid muscle was pulled to failure. Statistical analysis was performed to determine whether ALA reduced the lateral deltoid's failure load. There was no significant difference in failure load between the 5-mm ALA group (661 ± 207N) and its matched control group (744 ± 212N; mean difference= 83N; 95% confidence interval [CI], -91 to 258; P= .285) nor between the 10-mm ALA group (544 ± 210N) and its matched control group (598 ±157N; mean difference= 54N; 95% CI, -141 to 250; P= .532). There was no correlation found between the amount of bone resected (measured by percent thickness and width of the acromion after ALA) and the failure load of the deltoid. Visual evaluation of the acromion after ALA revealed the lateral deltoid origin had no damage in any case. ALA did not weaken the structural or mechanical integrity of the lateral deltoid origin. Neither a 5-mm nor a 10-mm ALA significantly reduced the deltoid's failure load. The lateral deltoid origin was not macroscopically damaged in any case. ALA can be performed without the potential risk of macroscopically damaging the lateral deltoid origin or reducing its failure load.

The Effects of Arthroscopic Lateral Acromioplasty on the Critical Shoulder Angle and the Anterolateral Deltoid Origin: An Anatomic Cadaveric Study

To investigate if (1) an anterolateral acromioplasty and (2) a lateral acromion resection alter the critical shoulder angle (CSA) without affecting the deltoid origin. First, the native CSAs of 10 human cadaveric shoulders (6 male and 4 female specimens; mean age, 54.2 years) were determined with the use of fluoroscopy. Setup allowed for consistent repetitive measurements. Next, a standard arthroscopic anterolateral acromioplasty was performed to create a type 1 acromion, and the CSA was reassessed fluoroscopically. Afterward, a lateral acromioplasty was performed with a 5-mm lateral acromion resection using a 5-mm burr, and the CSA was measured again. The native CSA was compared with (1) the CSA after acromioplasty and (2) the CSA after acromioplasty and lateral acromion resection using a paired t test. Finally, the acromial deltoid attachment was evaluated anatomically for damage to the anterolateral origin. The mean native CSA (34.3° ± 2.1°) was reduced significantly by acromioplasty (33.1° ± 2.0°, P < .001) and further reduced by lateral acromion resection (31.5° ± 1.7°, P < .001). Anterolateral acromioplasty reduced the CSA by a mean of 1.4° (95% confidence interval boundaries, 0.8° and 1.9°), and in combination with lateral acromion resection, the CSA was reduced by a mean of 2.8° (95% confidence interval boundaries, 2.1° and 3.5°). In all specimens (5 of 5) with a presurgery CSA of 35° or greater, the CSA was reduced to the range of 30° to 35° by the combination of both techniques. However, in 2 specimens with a CSA of approximately 32°, the CSA was reduced to less than 30°. The acromial deltoid attachment was found to be well preserved in all specimens. Arthroscopic anterolateral acromioplasty and a 5-mm lateral acromion resection each reduced the CSA significantly and did not damage the deltoid origin. The combination of both techniques could potentially be used in clinical practice to reduce a CSA greater than 35° to the desired range of 30° to 35°.

Alterations of the Deltoid Muscle After Open Versus Arthroscopic Rotator Cuff Repair

Background: Open repair can be more useful than arthroscopic repair for immobile and severely retracted, large to massive rotator cuff tears. However, it is not known whether the deltoid muscle is altered after open repair or to what extent the deltoid origin remains detached after surgery. Purpose: To compare postoperative alterations of the deltoid muscle in open versus arthroscopic repair for severely retracted, large to massive rotator cuff tears. Study Design: Case-control study; Level of evidence, 3. Methods: Enrolled in this study were 135 patients who underwent surgical repair for severely retracted, large to massive rotator cuff tears and who had routine follow-up MRIs at least 6 months after surgery. Open repairs were performed in 56 cases and arthroscopic repairs in 79 cases. The detachment and thickness of the deltoid muscle at its proximal origin were recorded in 5 zones on MRI. The alterations of the deltoid muscle and postoperative integrity of the repaired rotator cuff were evaluated. Results: Partial detachment of the deltoid occurred in 1 patient (1.8%) in the open group and in 2 patients (2.5%) in the arthroscopic group (P = .80). All the partial detachments occurred in zones 2 and 3. Attenuation of the proximal origin of the deltoid was found in 3 patients (5.4%) in the open group and in 4 patients (5.1%) in the arthroscopic group (P = .87). Atrophy of the deltoid muscle was shown in 3 patients (5.4%) in the open group and 4 patients (5.1%) in the arthroscopic group (P = .61). The retear rate of the repaired cuff was 30.4% (17/56) in the open group and 38.0% (30/79) in the arthroscopic group (P = .74). Conclusion: Between open and arthroscopic repair for severely retracted, large to massive rotator cuff tears, there was no significant difference in detachment of the deltoid origin and alterations of the deltoid muscle after repair. Postoperative alterations of the deltoid occurred in arthroscopic surgery as well as in open surgery. For immobile massive rotator cuff tear, open repair is an acceptable technique as long as the deltoid muscle is meticulously reattached after surgery.

Alterations of the Deltoid Muscle After Open Versus Arthroscopic Rotator Cuff Repair

Background:Open repair can be more useful than arthroscopic repair for immobile and severely retracted, large to massive rotator cuff tears. However, it is not known whether the deltoid muscle is altered after open repair or to what extent the deltoid origin remains detached after surgery.Purpose:To compare postoperative alterations of the deltoid muscle in open versus arthroscopic repair for severely retracted, large to massive rotator cuff tears.Study Design:Case-control study; Level of evidence, 3.Methods:Enrolled in this study were 135 patients who underwent surgical repair for severely retracted, large to massive rotator cuff tears and who had routine follow-up MRIs at least 6 months after surgery. Open repairs were performed in 56 cases and arthroscopic repairs in 79 cases. The detachment and thickness of the deltoid muscle at its proximal origin were recorded in 5 zones on MRI. The alterations of the deltoid muscle and postoperative integrity of the repaired rotator cuff were evaluated.Results:Part...

Limb-Length Discrepancy After Hip Arthroplasty

Background: Acromial fractures following reverse shoulder arthroplasty are difficult to identify and have variable effects on outcomes. A reproducible classification system is needed to categorize these fractures before it is possible to evaluate optimal treatment. The purposes of this study were to investigate the ability of radiographs to detect acromial fractures and establish fracture union, and to assess the reliability of a new classification system of postoperative acromial fractures based on the involvement of the deltoid origin. Methods: Eighteen patients presenting with pain along the acromion or scapular spine following reverse shoulder arthroplasty were evaluated for acromial fractures over a period of fifty-six months. If radiographic findings were negative, computed tomography (CT) scans were performed. Sixteen acromial fractures were identified and classified into subtypes on the basis of the deltoid muscle origin: type I indicated involvement of a portion of the anterior and middle deltoid origin; type II, at least the entire middle deltoid origin with a portion but not all of the posterior deltoid origin; and type III, the entire middle and posterior deltoid origin. The average age of the patients at the time of surgery was seventy-seven years (range, fifty-seven to eighty-seven years); the average duration of follow-up after surgery was twenty-five months (range, seven to forty-eight months). All fractures were treated nonoperatively. Blinded, fellowship-trained shoulder surgeons reviewed images that best illustrated the fracture, and the interobserver reliability of the classification system was evaluated. The reliability of radiographs to detect the fracture at the time of the initial presentation of pain and to observe ultimate fracture union was evaluated. Results: Interobserver reliability of the classification system was excellent (interclass correlation coefficient of 0.96). Radiographs were unreliable at detecting acromial fractures at the time of the initial presentation of pain (κ = −0.5) and at determining fracture union (κ = 0.05). Conclusions: Radiographs may be unreliable for detecting acromial fractures after reverse total shoulder arthroplasty, and CT scans are often needed to identify the fracture. Once identified, postoperative acromial fractures can be reliably classified into three subtypes. Nonoperative treatment of postoperative acromial fractures results in limitation of functional outcomes. Level of Evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.