Complications of Shoulder Arthroplasty

Rotator cuff contact pressures at the tendon-implant interface after anatomic total shoulder arthroplasty using a metal-backed glenoid component

BACKGROUND

Rotator cuff tears following anatomic total shoulder arthroplasty increase with duration of follow-up. This study aimed to evaluate contact pressure between the rotator cuff tendons and prosthesis after anatomic total shoulder arthroplasty and compare these with the tendon-contact pressures in the native shoulder.

METHODS

Eight entire upper extremities were mounted onto a testing apparatus, and simulated muscle loading was applied to each rotator cuff tendon with the shoulder positioned in abduction, internal rotation, and external rotation. Pressure-sensitive film placed between each tendon and bone was used to measure the resultant tendon contact pressures. Experiments were repeated after anatomic total shoulder arthroplasty using standardized implant sizes, and pressure-sensitive film was used to evaluate tendon-prosthesis contact pressure.

RESULTS

Both joint angle and shoulder joint replacement surgery had significant effects on the maximum contact pressure measured between the humeral head and all rotator cuff tendons (P < .05) except the teres minor. The supraspinatus demonstrated a significantly larger peak tendon contact pressure after surgery at 45° of abduction relative to that in the native shoulder (mean difference, 0.2 MPa; P = .031), while the subscapularis had a significantly larger maximum contact pressure at 10° of abduction (mean difference, 0.45 MPa; P = .032) and 90° of abduction (mean difference, 0.80 MPa; P = .008) postoperatively.

CONCLUSION

Anatomic total shoulder arthroplasty results in significantly larger tendon contact pressures relative to those in the native shoulder. High tendon contact pressures may ultimately predispose rotator cuff tendons to postoperative wear-induced damage and tearing.

Analysis of 4063 complications of shoulder arthroplasty reported to the US Food and Drug Administration from 2012 to 2016

BACKGROUND

Most of the literature on shoulder arthroplasty failure comes from high-volume centers. These reports tend to exclude the experience of community orthopedic surgeons, who perform most of the shoulder joint replacements.

METHODS

We analyzed the failure reports mandated by the US Food and Drug Administration for all hospitals. Each reported event from 2012 to 2016 was characterized by implant, failure mode, and year of surgery.

RESULTS

For the 1673 anatomic arthroplasties, the most common failure modes were glenoid component failure (20.4%), rotator cuff/subscapularis tear (15.4%), pain/stiffness (12.9%), dislocation/instability (11.8%), infection (9%), and humeral component loosening (5.1%). For the 2390 reverse arthroplasties, the most common failure modes were dislocation/instability (32%), infection (13.8%), glenosphere-baseplate dissociation (12.2%), failed/loosened baseplate (10.4%), humeral component dissociation/tray fracture (5.5%), difficulty inserting the baseplate (4.8%), and difficulty inserting the glenosphere (4.2%). Although the percentage distribution among the different failure modes was relatively consistent over the years of this study, the percentage distribution of these failure modes differed substantially among different implant manufacturers.

CONCLUSIONS

The Food and Drug Administration database reveals modes of shoulder arthroplasty failure that are not emphasized in the published literature, such as rotator cuff tear, infection, and postoperative pain/stiffness for anatomic total shoulder arthroplasty and implant dissociation and baseplate failure for reverse shoulder arthroplasty. Knowledge of these failure modes may help inform surgical technique and implant design in ways that will lower the risk of implant failure in the future.

Bone remodelling of the humerus after a resurfacing and a stemless shoulder arthroplasty

BACKGROUND

New implant designs, such as resurfacing and stemless implants, have been developed to improve the long-term outcomes of the shoulder arthroplasty. However, it is not yet fully understood if their influence on the bone load distribution can compromise the long-term stability of the implant due to bone mass changes. Using three-dimensional finite element models, the aim of the present study was to analyse the bone remodelling process of the humerus after the introduction of resurfacing and stemless implants based on the Global C.A.P. and Sidus Stem-Free designs, respectively.

METHODS

The 3D geometric model of the humerus was generated from the CT data of the Visible Human Project and the resurfacing and stemless implants were modelled in Solidworks. Considering a native humerus model, a humerus model with the resurfacing implant, and a humerus model with the stemless implant, three finite element models were developed in Abaqus. Bone remodelling simulations were performed considering healthy and poor bone quality conditions. The loading condition considered comprised 6 load cases of standard shoulder movements, including muscle and joint reaction forces estimated by a multibody model of the upper limb.

FINDINGS

The results showed similar levels of bone resorption for the resurfacing and stemless implants for common humeral regions. The regions underneath the head of the resurfacing implant, unique to this design, showed the largest bone loss. For both implants, bone resorption was more pronounced for the poor bone quality condition than for the healthy bone quality condition.

INTERPRETATION

The stemless implant lost less density at the fixation site, which might suggest that these implants may be better supported in the long-term than the resurfacing implants. However, further investigation is necessary to allow definite recommendations.

Growth of Cutibacterium acnes is common on osteosynthesis material of the shoulder in patients without signs of infection

Background and purpose - Cutibacterium acnes, formerly known as Propionibacterium acnes, is often isolated from deep tissues of the shoulder. It is recognized as an important causative agent of foreign-material associated infections. However, the incidence and significance of its detection in tissues from patients without clinical evidence for infection is unclear. We assessed the incidence of C. acnes colonization of osteosynthesis material in asymptomatic patients, and evaluated the short-term outcome in relation to the microbiological findings. Patients and methods - We microbiologically analyzed osteosynthesis material of 34 asymptomatic patients after surgery on the clavicle. Material obtained from 19 asymptomatic patients after osteosynthesis of the fibula served as a control group. Patients were clinically followed up for 3-24 months after removal of the osteosynthesis material. Results - Bacteria were recovered from devices in 29 of 34 patients from the clavicle group. 27 of 29 positive samples grew C. acnes. Isolation of C. acnes was more common in male than in female patients. No bacterial growth was observed on foreign material from patients in the fibula group. All patients remained asymptomatic at follow-up. Interpretation - Growth of C. acnes is common on osteosynthesis material of the shoulder, especially in males. Samples were positive irrespective of clinical signs of infection. Therefore, detection of C. acnes in this clinical setting is of questionable clinical significance. The high positivity rate in asymptomatic patients discourages routine sampling of material in cases without clinical evidence for infection.

Impact of Modeling Assumptions on Stability Predictions in Reverse Total Shoulder Arthroplasty

Reverse total shoulder arthroplasty (rTSA) is commonly used in the shoulder replacement surgeries for the relief of pain and to restore function, in patients with grossly deficient rotator cuff. Primary instability due to glenoid loosening is one of the critical complications of rTSA; the implants are designed and implanted such that the motion between the glenoid baseplate and underlying bone is minimized to facilitate adequate primary fixation. Finite element analysis (FEA) is commonly used to simulate the test setup per ASTM F2028-14 for comparing micromotion between designs or configurations to study the pre-clinical indications for stability. The FEA results can be influenced by the underlying modeling assumptions. It is a common practice to simplify the screw shafts by modeling them as cylinders and modeling the screw-bone interface using bonded contact, to evaluate micromotion in rTSA components. The goal of this study was to evaluate the effect of three different assumptions for modeling the screw-bone interface on micromotion predictions. The credibility of these modeling assumptions was examined by comparing the micromotion rank order predicted among three different modular configurations with similar information from the literature. Eight configurations were modeled using different number of screws, glenosphere offset, and baseplate sizes. An axial compression and shear load was applied through the glenosphere and micromotion at the baseplate-bone interface was measured. Three modeling assumptions pertaining to modeling of the screw-bone interface were used and micromotion results were compared to study the effect of number of peripheral screws, eccentricities, and baseplate diameter. The relative comparison of micromotion between configurations using two versus four peripheral screws remained unchanged irrespective of the three modeling assumptions. However, the relative comparison between two inferior offsets and baseplate sizes changed depending on the modeling assumptions used for the screw-bone interface. The finding from this study challenges the generally believed hypothesis that FEA models can be used to make relative comparison of micromotion in rTSA designs as long as the same modeling assumptions are used across all models. The comparisons with previously published work matched the finding from this study in some cases, whereas the comparison was contradicting in other cases. It is essential to validate the computer modeling approach with an experiment using similar designs and methods to increase the confidence in the predictions to make design decisions.

Risk and risk factors for revision after primary reverse shoulder arthroplasty for cuff tear arthropathy and osteoarthritis: a Nordic Arthroplasty Register Association study

BACKGROUND

Reverse shoulder arthroplasty (RSA) has gained increasing popularity in the treatment of rotator cuff tear arthropathy (CTA). The purpose of this study was to evaluate the survival of RSA and the risk factors for revision following RSA.

METHODS

RSA patients with CTA or osteoarthritis were identified from the Nordic Arthroplasty Register Association registry data (2004-2013). Kaplan-Meier survival analysis was used to calculate survival probabilities. Cox multiple regression analysis was used to calculate revision rates adjusted for sex, arthroplasty brand, age (<70 years), and year of surgery.

RESULTS

The study included 1904 patients with RSA (1904 RSAs) (69% women; mean age, 74 years; age range, 35-97 years). Revision was performed in 95 patients (5%), with a 10-year cumulative revision rate of 0.91. The most common reason for revision was infection (n = 42), followed by loosening (n = 16) and instability (n = 12). Most revisions occurred less than 6 months after the primary operation. Men had a significantly increased risk of revision compared with women (risk ratio, 3.8; 95% confidence interval, 2.4-6.1). The most common implants were the Delta Xtend (n = 1366) and Delta Mark III (n = 246). The risk of revision of the Delta Mark III was 2.1 (95% confidence interval, 1.1-4.3) compared with the Delta Xtend. Age and year of surgery were not statistically significantly associated with risk of revision.

CONCLUSION

The overall midterm risk of revision after RSA for CTA was low (5%). The most common reason for early revision was infection. Male sex was associated with a significantly increased risk of revision.

Use of Patient-Specific Instrumentation (PSI) for glenoid component positioning in shoulder arthroplasty. A systematic review and meta-analysis

INTRODUCTION

Total Shoulder Arthroplasty (TSA) anatomical, reverse or both is an increasingly popular procedure but the glenoid component is still a weak element, accounting for 30-50% of mechanical complications and contributing to the revision burden. Component mal-positioning is one of the main aetiological factors in glenoid failure and thus Patient-Specific Instrumentation (PSI) has been introduced in an effort to optimise implant placement. The aim of this systematic literature review and meta-analysis is to compare the success of PSI and Standard Instrumentation (STDI) methods in reproducing pre-operative surgical planning of glenoid component positioning.

MATERIAL AND METHODS

A search (restricted to English language) was conducted in November 2017 on MEDLINE, the Cochrane Library, EMBASE and ClinicalTrials.gov. Using the search terms "Patient-Specific Instrumentation (PSI)", "custom guide", "shoulder", "glenoid" and "arthroplasty", 42 studies were identified. The main exclusion criteria were: no CT-scan analysis results; studies done on plastic bone; and use of a reusable or generic guide. Eligible studies evaluated final deviations from the planning for version, inclination, entry point and rotation. Reviewers worked independently to extract data and assess the risk of bias on the same studies.

RESULTS

The final analysis included 12 studies, comprising 227 participants (seven studies on 103 humans and five studies on 124 cadaveric specimens). Heterogeneity was moderate or high for all parameters. Deviations from the pre-operative planning for version (p<0.01), inclination (p<0.01) and entry point (p = 0.02) were significantly lower with the PSI than with the STDI, but not for rotation (p = 0.49). Accuracy (deviation from planning) with PSI was about 1.88° to 4.96°, depending on the parameter. The number of component outliers (>10° of deviation or 4mm) were significantly higher with STDI than with PSI (68.6% vs 15.3% (p = 0.01)).

CONCLUSION

This review supports the idea that PSI enhances glenoid component positioning, especially a decrease in the number of outliers. However, the findings are not definitive and further validation is required. It should be noted that no randomised clinical studies are available to confirm long-term outcomes.

Imaging of Shoulder Arthroplasties

OBJECTIVE

In this article, we review the preoperative imaging features used for planning shoulder arthroplasty as well as review the various shoulder arthroplasty component types, discussing the expected normal imaging features and specific complications to look for with each.

CONCLUSION

Given the increasing use of shoulder arthroplasty, it is important to understand the imaging features of the various shoulder arthroplasty complications.

Preoperative Doxycycline Does Not Reduce Propionibacterium acnes in Shoulder Arthroplasty

BACKGROUND

Propionibacterium acnes (P. acnes) is the most common bacteria associated with infection after shoulder arthroplasty. These bacteria can be grown on culture of skin after standard preoperative skin preparation and antibiotics. The purpose of this study was to determine whether adding preoperative intravenous doxycycline reduces the prevalence of positive P. acnes cultures of skin and deep tissues at the time of prosthetic joint implantation during shoulder arthroplasty.

METHODS

This was a randomized controlled trial. An a priori power analysis determined that a sample size of 56 patients was necessary. Patients scheduled to undergo shoulder arthroplasty were randomized to receive either standard perioperative cefazolin or a combination of doxycycline and cefazolin. Tissue specimens for culture were then taken from the skin edge, and swabs of the superficial dermal tissue and glenohumeral joint were obtained. All cultures were maintained for 14 days to allow for P. acnes detection. Groups were compared to determine if the addition of doxycycline reduced the rate of culture positivity.

RESULTS

Fifty-six patients were enrolled and randomized. Twenty-one (38%) had ≥1 positive cultures for P. acnes, with no significant difference between the group treated with cefazolin alone (10 [37%] of 27 patients) and the combined doxycycline and cefazolin group (11 [38%] of 29 patients) (p = 0.99). The greatest numbers of culture-positive samples were obtained from the skin (30%), followed by dermal tissue (20%) and the glenohumeral joint (5%). Patients who had ≥1 positive cultures were younger than those who did not (mean age [and standard deviation], 64.9 ± 7.7 versus 69.4 ± 7.7 years; p = 0.041), had a greater tendency to be male (16 [76%] of 21 versus 17 [49%] of 35; p = 0.053), and had a lower Charlson Comorbidity Index (3.35 ± 1.3 versus 4.09 ± 1.4; p = 0.051). There were no significant differences between the culture-positive and culture-negative groups in terms of body mass index (BMI) (p = 0.446) or arthroplasty type, with positive cultures found for 8 of the 29 anatomic shoulder arthroplasty procedures compared with 13 of the 27 reverse shoulder arthroplasty procedures (p = 0.280). There were no doxycycline-related adverse events.

CONCLUSIONS

In this randomized controlled trial, doxycycline did not significantly decrease P. acnes culture positivity of the skin, dermis, or glenohumeral joint of patients undergoing shoulder arthroplasty. The addition of prophylactic intravenous antibiotics to cover P. acnes may not be an effective method to reduce postoperative and periprosthetic shoulder joint infections.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Anatomical total shoulder arthroplasty used for glenohumeral osteoarthritis has higher survival rates than hemiarthroplasty: a Nordic registry-based study

OBJECTIVE

To report the10-year survival rates of different shoulder arthroplasty types used for glenohumeral osteoarthritis.

DESIGN

Data from 2004 to 2013 was prospectively collected by the national shoulder arthroplasty registers in Denmark, Norway and Sweden and merged into a harmonized dataset under the umbrella of the Nordic Arthroplasty Register Association. The common dataset included data that all three registers could deliver and where consensus regarding definitions could be made. Revision was defined as removal or exchange of any component or the addition of a glenoid component.

RESULTS

The cumulative survival rates at 10 years after resurfacing hemiarthroplasty (RHA) (n = 1,923), stemmed hemiarthroplasty (SHA) (n = 1,587) and anatomical total shoulder arthroplasty (TSA) (n = 2,340) were 0.85, 0.93 and 0.96 respectively (P < 0.001, Log rank test). RHA (HR: 2.5; CI 1.9-3.4, P < 0.001) and SHA (HR: 1.4; CI 1.0-2.0, P < 0.04) had an increased risk of revision compared to TSA. Gender, age and period of surgery were included in the Cox regression model. For patients below 55 years, the 10-year cumulative survival rates were 0.75 (RHA, n = 354), 0.81 (SHA, n = 146), and 0.87 (TSA, n = 201).

CONCLUSIONS

Anatomical TSA had the highest implant-survival rate. Young patients had, independently of the arthroplasty type, lower implant-survival rates. The treatment of young patients with end-stage osteoarthritis remains a challenge.

Relative Complications and Trends of Outpatient Total Shoulder Arthroplasty

Outpatient arthroplasty is an appealing option among select patient populations as a mechanism for reducing health care expenditure. The purpose of this study was to determine the nationwide trends and complication profile of outpatient total shoulder arthroplasty (TSA). The authors reviewed a national administrative claims database to identify patients undergoing TSA as outpatients and inpatients from 2007 to 2016. The incidence of perioperative surgical and medical complications was determined by querying for relevant International Classification of Diseases, Ninth Revision, and Current Procedural Terminology codes. Multivariate logistic regression adjusted for age, sex, and Charlson Comorbidity Index was used to calculate odds ratios of complications among outpatients relative to inpatients undergoing TSA. The query identified 1555 patients who underwent outpatient TSA and 15,987 patients who underwent inpatient TSA. The median age was in the 70 to 74 years age group in both the outpatient and the inpatient cohorts, and the age distribution was comparable between the 2 cohorts (P=.287). The incidence of both outpatient (P<.001) and inpatient (P<.001) TSA increased during the study period. On adjustment for age, sex, and comorbidities, patients undergoing outpatient TSA had significantly lower rates of stiffness requiring manipulation under anesthesia (outpatient, 1.09%; inpatient, 2.35%; odds ratio, 0.52; 95% confidence interval, 0.38-0.71; P<.001) and higher rates of postoperative surgical site infections requiring reoperation (outpatient, 0.90%; inpatient, 0.65%; odds ratio, 1.65; 95% confidence interval, 1.15-2.35; P<.001) at 1 year. Rates of all other postoperative complications were comparable. Ambulatory TSA is increasing in incidence nationwide and is associated with an overall favorable postoperative complication profile. [Orthopedics. 2018; 41(3):e400-e409.].

Anatomical and biomechanical framework for shoulder arthroplasty rehabilitation

This article provides an anatomical and biomechanical framework for the postoperative management and progression of treatment for shoulder arthroplasty. The clinical relevance of normal shoulder anatomy, biomechanics, and pathomechanics related to this surgery is emphasized to provide the reader with an understanding of the rationale for treatment. We review the rehabilitation implications of surgical indications and technique for both traditional total shoulder arthroplasty and reverse total shoulder arthroplasty procedures with an emphasis on biomechanical considerations. Relevant factors that affect rehabilitation outcomes are discussed along with supporting evidence from the literature. Principles to guide and progress treatment are highlighted with a discussion on return to sports with the ultimate objective of providing a comprehensive approach for successful rehabilitation.

Regional anesthesia decreases complications and resource utilization in shoulder arthroplasty patients

BACKGROUND

Regional anesthesia can be used as part of the anesthetic to optimize anesthesia and analgesia during shoulder arthroplasty, but little is known about the overall effect that regional anesthesia has on perioperative outcomes and resource utilization. We hypothesized that regional anesthesia may decrease complication rates and resource utilization in shoulder arthroplasty patients.

METHODS

We examined administrative data from 588 US hospitals from 2010 to 2015. Logistic regression was used to examine the relationship between type of anesthesia and perioperative complications.

RESULTS

Among patients who underwent shoulder arthroplasty, 79.1% (53,243) had general anesthesia alone, 17.8% (12,011) had general anesthesia and a nerve block, and 3.1% (2062) had a nerve block alone. Overall, the complication rate was 13.3% and 30-day mortality was 1.2 per 1000 (95% CI 0.9, 1.4). In adjusted analyses, patients who had general anesthesia alone (compared to general anesthesia and nerve block) had a 16% increase in all cause infectious complications (OR 1.16, 95% CI: 1.03, 1.31) and were 2.6 times more likely to develop pulmonary complications (OR 2.6, 95% CI: 1.14, 5.78). General anesthesia alone (relative to either block only or general anesthesia and block) was associated with substantial increases in the likelihood of blood transfusions, intensive care unit transfers, and prolonged length of stay.

CONCLUSION

Patients receiving regional anesthesia for shoulder arthroplasty may have a reduction in perioperative complications, the need for intensive care unit transfers, blood transfusions, and prolonged hospital stays.

Improving the surface properties of an UHMWPE shoulder implant with an atmospheric pressure plasma jet

Insufficient glenoid fixation is one of the main reasons for failure in total shoulder arthroplasty. This is predominantly caused by the inert nature of the ultra-high molecular weight polyethylene (UHMWPE) used in the glenoid component of the implant, which makes it difficult to adhesively bind to bone cement or bone. Previous studies have shown that this adhesion can be ameliorated by changing the surface chemistry using plasma technology. An atmospheric pressure plasma jet is used to treat UHMWPE substrates and to modify their surface chemistry. The modifications are investigated using several surface analysis techniques. The adhesion with bone cement is assessed using pull-out tests while osteoblast adhesion and proliferation is also tested making use of several cell viability assays. Additionally, the treated samples are put in simulated body fluid and the resulting calcium phosphate (CaP) deposition is evaluated as a measure of the in vitro bioactivity of the samples. The results show that the plasma modifications result in incorporation of oxygen in the surface, which leads to a significant improved adhesion to bone cement, an enhanced osteoblast proliferation and a more pronounced CaP deposition. The plasma-treated surfaces are therefore promising to act as a shoulder implant.

What can be learned from an analysis of 215 glenoid component failures?

BACKGROUND

Glenoid component failure is a prevalent mechanical complication of anatomic total shoulder arthroplasty. The objective of this study was to identify surgeon-controlled factors that may be addressed to reduce the rate of glenoid component failure that is sufficiently symptomatic to merit surgical revision.

METHODS

We reviewed the clinical and radiographic features of 215 total shoulder arthroplasties that we revised for symptomatic glenoid component failure.

RESULTS

Glenoid component failure was associated with poor patient self-assessed shoulder function (mean Simple Shoulder Test score, 3.0 ± 2.7). These shoulders often showed multiple failure modes; 72% had glenoid component loosening, 69% had polyethylene wear, 51% had glenohumeral decentering, and 25% had humeral component loosening. Metal-backed/hybrid and keeled glenoid designs had higher rates of loosening (P = .010), malposition (P = .007), dislocation (P < .001), and early failure (P = .044) in comparison to pegged designs. Glenoid components with cement on the backside were more prevalent among those revised sooner than 5 years after the index surgery (P < .001).

CONCLUSIONS

Glenoid component failure remains a major cause of poor patient outcomes after total shoulder arthroplasty. The occurrence of severe glenoid component failure might be reduced by paying attention to glenoid component design and insertion technique, restoring the normal balance of the humeral head in the center of the glenoid, and considering a reverse total shoulder when the shoulder is unstable because of soft tissue deficiency.

Radiological changes do not influence clinical mid-term outcome in stemless humeral head replacements with hollow screw fixation: a prospective radiological and clinical evaluation

Background

Stemless shoulder arthroplasty is a fairly new concept. Clinical and radiological follow-up is essential to prove implant safety and concept. This prospective single-centre study was performed to evaluate the influence of radiological changes on clinical mid-term outcome following stemless humeral head replacement with hollow screw fixation.

Methods

Short- and mid-term radiological and clinical evaluations were performed in 73 consecutive shoulders treated mainly for idiopathic and posttraumatic osteoarthritis with stemless humeral head arthroplasty including 40 hemi- (HSA) and 33 total shoulder arthroplasties (TSA). Operating times of stemless implantations were compared to 110 stemmed anatomical shoulder prostheses. Appearances of humeral radiolucencies or radiological signs of osteolysis or stress shielding were assessed on standardized radiographs. Patients’ clinical outcome was evaluated using the Constant score and patients’ satisfaction was documented.

Results

Radiological changes, detected in 37.0%, did not affect clinical outcome. Constant scores significantly improved from baseline to short and mid-term follow-up (p < 0.001). The majority of patients (96.2%) were satisfied with the procedure. No loosening of the humeral head component was detected during a mean follow-up of 58 months. Operating times were significantly shorter with stemless compared to stemmed implants (p < 0.001).

Conclusions

Clinical mid-term outcome after stemless humeral head replacement was not affected by radiological changes.

Trial registration

The institutional review board (St. Vincent Hospital Vienna; 201212_EK01; date of issue: 11.12.2012) approved the study. The trial was registered at ClinicalTrials.gov (NCT02754024). Retrospective registration.

Preliminary Results of Arthroscopic Superior Capsule Reconstruction with Dermal Allograft

PURPOSE

The purpose of this study was to evaluate the short-term outcomes of arthroscopic superior capsule reconstruction (SCR) with dermal allograft for the treatment of irreparable massive rotator cuff tears (MRCTs).

METHODS

A multicenter study was performed on patients undergoing arthroscopic SCR for irreparable MRCTs. The minimum follow-up was 1 year. Range of motion and functional outcome according to visual analog scale (VAS) pain, American Shoulder and Elbow Surgeons (ASES) score, and subjective shoulder value (SSV) score were assessed preoperatively and at final follow-up. Radiographs were used to evaluate the acromiohumeral interval (AHI).

RESULTS

Fifty-nine patients with a mean age of 62.0 years had a minimum follow-up of 1 year. Twenty-five patients (42.4%) had a prior rotator cuff repair. Forward flexion improved from 130° preoperative to 158° postoperative, and external rotation improved from 36° to 45°, respectively (P < .001). Compared with preoperative values, the VAS decreased from 5.8 to 1.7, the ASES score improved from 43.6 to 77.5, and the SSV score improved from 35.0 to 76.3 (P < .001). The AHI was 6.6 mm at baseline and improved to 7.6 mm at 2 weeks postoperatively but decreased to 6.7 mm at final follow-up. Based on postoperative magnetic resonance imaging, 45% (9 of 20) of the grafts demonstrated complete healing. Forty-six (74.6%) cases were considered a success. Eleven patients (18.6%) underwent a revision procedure including 7 reverse shoulder arthroplasties.

CONCLUSIONS

Arthroscopic SCR using dermal allograft provides a successful outcome in approximately 70% of cases in an initial experience. The preliminary results are encouraging in this difficult to manage patient population, but precise indications are important and graft healing is low in our initial experience.

LEVEL OF EVIDENCE

Level IV, case series.

Surgical anatomy of the radial nerve in the deltopectoral approach for revision shoulder arthroplasty and periprosthetic fracture fixation: a cadaveric study

BACKGROUND

Radial nerve injury is a rare but clinically significant complication of revision shoulder arthroplasty and fixation of native and periprosthetic proximal humeral fractures. Understanding of the anatomic relationship between the radial nerve as it enters the humeral spiral groove and anterior shoulder landmarks in a deltopectoral approach is necessary to avoid iatrogenic radial nerve injury.

METHODS

Eight forequarter cadaveric specimens were dissected through a deltopectoral approach. Distances between the radial nerve entry into the proximal spiral groove and the coracoid process, distal lesser tuberosity/inferior subscapularis insertion, superior latissimus insertion, and inferior latissimus insertion were measured. Means, standard deviations, and ranges were determined for each distance.

RESULTS

The radial nerve entry into the proximal spiral groove averaged 133.1 mm (range, 110.3-153.0 mm) from the coracoid process, 101.9 mm (range, 76.5-124.3 mm) from the distal lesser tuberosity/inferior subscapularis insertion, 81.0 mm (range, 63.4-101.5 mm) from the superior latissimus insertion, and 39.6 mm (range, 25.5-55.4 mm) from the inferior latissimus insertion. The proximal spiral groove was distal to the inferior latissimus insertion in all specimens.

CONCLUSION

The risk of iatrogenic injury to the radial nerve at the spiral groove may be minimized through proper identification and protection or avoidance of circumferential fixation. However, if encircling fixation with cerclage cables is necessary, instrumentation proximal to the inferior edge of the latissimus dorsi insertion may reduce the risk of radial nerve injury.

Restoration of the joint geometry and outcome after stemless TESS shoulder arthroplasty

AIM

To evaluate the joint geometry and the clinical outcome of stemless, anatomical shoulder arthroplasty with the TESS system.

METHODS

Twenty-one shoulders with a mean follow-up 18 of months were included. On scaled digital radiographs the premorbid center of rotation (CoR) was assessed and compared to the CoR of the prosthesis by using the MediCAD^® software. Additionally, the pre- and post-operative geometry of the CoR was assessed in relation to the glenoid, the acromion as well as to the proximal humerus. Radiological changes, such as radiolucencies, were also assessed. Clinical outcome was assessed with the Constant and DASH score.

RESULTS

Both, the Constant and DASH scores improved significantly from 11% to 75% and from 70 to 30 points, P < 0.01 respectively. There were no significant differences regarding age, etiology, cemented or metal-backed glenoids, etc. (P > 0.05). The pre- and postoperative humeral offset, the lateral glenohumeral offset, the height of the CoR, the acromiohumeral distance as well as neck-shaft angle showed no significant changes (P > 0.05). The mean deviation of the CoR of the prosthesis from the anatomic center was 1.0 ± 2.8 mm. Three cases showed a medial deviation of more than 3 mm. These deviations of 5.1, 5.7 and 7.6 mm and were caused by an inaccurate humeral neck cut. These 3 patients showed a relatively poor outcome scoring.

CONCLUSION

TESS arthroplasty allows an anatomical joint reconstruction with a very good outcome. Outliers described in this study sensitize the surgeon for an accurate humeral neck cut.