Glenoid Cartilage Research Articles

Hemiarthroplasty in young patients.

The survival of humeral hemiarthroplasties in patients with relatively intact glenoid cartilage could theoretically be extended by minimizing the associated postoperative glenoid erosion. Ceramic has gained attention as an alternative to metal as a material for hemiarthroplasties because of its superior tribological properties. The aim of this study was to assess the in vitro wear performance of ceramic and metal humeral hemiarthroplasties on natural glenoids. Intact right cadaveric shoulders from donors aged between 50 and 65 years were assigned to a ceramic group (n = 8, four male cadavers) and a metal group (n = 9, four male cadavers). A dedicated shoulder wear simulator was used to simulate daily activity by replicating the relevant joint motion and loading profiles. During testing, the joint was kept lubricated with diluted calf serum at room temperature. Each test of wear was performed for 500,000 cycles at 1.2 Hz. At intervals of 125,000 cycles, micro-CT scans of each glenoid were taken to characterize and quantify glenoid wear by calculating the change in the thickness of its articular cartilage. At the completion of the wear test, the total thickness of the cartilage had significantly decreased in both the ceramic and metal groups, by 27% (p = 0.019) and 29% (p = 0.008), respectively. However, the differences between the two were not significant (p = 0.606) and the patterns of wear in the specimens were unpredictable. No significant correlation was found between cartilage wear and various factors, including age, sex, the size of the humeral head, joint mismatch, the thickness of the native cartilage, and the surface roughness (all p > 0.05). Although ceramic has better tribological properties than metal, we did not find evidence that its use in hemiarthroplasty of the shoulder in patients with healthy cartilage is a better alternative than conventional metal humeral heads.

Characterization of articular lesions associated with glenohumeral instability using arthroscopy.

The prevalence of osteoarthritis (OA) associated with instability of the shoulder ranges between 4% and 60%. Articular cartilage is, however, routinely assessed in these patients using radiographs or scans (2D or 3D), with little opportunity to record early signs of cartilage damage. The aim of this study was to assess the prevalence and localization of chondral lesions and synovial damage in patients undergoing arthroscopic surgery for instablility of the shoulder, in order to classify them and to identify risk factors for the development of glenohumeral OA. A total of 140 shoulders in 140 patients with a mean age of 28.5 years (15 to 55), who underwent arthroscopic treatment for recurrent glenohumeral instability, were included. The prevalence and distribution of chondral lesions and synovial damage were analyzed and graded into stages according to the division of the humeral head and glenoid into quadrants. The following factors that might affect the prevalence and severity of chondral damage were recorded: sex, dominance, age, age at the time of the first dislocation, number of dislocations, time between the first dislocation and surgery, preoperative sporting activity, Beighton score, type of instability, and joint laxity. A total of 133 patients (95%) had synovial or chondral lesions. At the time of surgery, shoulders were graded as having mild, moderate, and severe OA in 55 (39.2%), 72 (51.4%), and six (4.2%) patients, respectively. A Hill-Sachs lesion and fibrillation affecting the anteroinferior glenoid cartilage were the most common findings. There was a significant positive correlation between the the severity of the development of glenohumeral OA and the patient's age, their age at the time of the first dislocation, and the number of dislocations (p = 0.004, p = 0.011, and p = 0.031, respectively). Synovial inflammation and chondral damage associated with instability of the shoulder are more prevalent than previously reported. The classification using quadrants gives surgeons more information about the chondral damage, and could explain the pattern of development of glenohumeral OA after stabilization of the shoulder. As the number of dislocations showed a positive correlation with the development of OA, this might be an argument for early stabilization.

Changes in the Articular Cartilage Thickness in Patients with Symptomatic Rotator Cuff Tears: A Prospective Study with a Mean 5-Year Follow-Up.

Objectives: The purpose of this study was to prospectively investigate the progression of cartilage thinning in patients with symptomatic rotator cuff tears using MRI. Methods: Two hundred twenty-five consecutive patients with symptomatic rotator cuff tears visited our institute between 2009 and 2019. Of these, 28 shoulders of 27 patients (mean age, 65 years) who underwent at least two magnetic resonance imaging (MRI) examinations were prospectively enrolled. They all received conservative treatment. The mean follow-up was 67 months. Changes in cartilage thickness and the combined cartilage and subchondral bone thickness at the initial and final MRI were measured using a RadiAnt DICOM-viewer (Medixant, Poznan, Poland). The cartilage thickness of the humeral head was measured in the oblique coronal and sagittal images. The glenoid cartilage was measured in the axial and oblique coronal images. Results: At an average period of 5 years, 12 of 28 shoulders (42%) showed more than a 30% decrease in cartilage thickness in the humeral head. The glenoid showed cartilage thinning in only one shoulder (4%). In the humeral head, progressive cartilage thinning was seen mainly in the anterior and posterior parts of the humeral head in the sagittal plane. In the glenoid, progressive cartilage thinning was seen on the entire surface except the posterior area. There was no significant difference in cartilage thickness between the first and final follow-ups for both the humeral head and the glenoid. Conclusions: A total of 12 of 28 shoulders (42%) showed more than a 30% decrease in cartilage thickness in the humeral head, which was mainly observed in the anterior and posterior areas of the humeral head.

Comparison of the Latarjet Procedure and Iliac Crest Bone Graft Transfer in Bone Bankart Lesions in Recurrent Anterior Shoulder Dislocations.

There are various treatment modalities for bony Bankart lesions following glenohumeral joint dislocations. In this research, we aimed to compare the radiological and clinical results of patients who underwent the Latarjet procedure and iliac crest bone graft transfer. Clinical and radiological data of 15 patients were retrospectively evaluated. Inclusion criteria were a history of at least two dislocations, being between 18-65 years of age and having at least 10% glenoid bone loss. The exclusion criteria were defined as follows: patients who underwent only soft tissue procedures, patients who did not attend the follow-up, patients with other pathology in the upper extremity (fracture, cuff tear, etc.), and patients with a follow-up period of less than 12 months time. Nine patients underwent the Latarjet procedure and six underwent iliac crest bone graft transfer. Clinical evaluation, age, gender, body mass index, range of motion, Quick Disabilities of the Arm, Shoulder and Hand (QDASH) score, Constant score, and Visual Analogue Scale (VAS) score were evaluated. Radiographic evaluation was performed with preoperative and postoperative direct radiographs and computed tomography. Mann-Whitney U test, t-test, and Fisher exact tests were used for group comparisons. The mean age of the patients was 32.6 years and the mean follow-up period was 24.9 months. When the two groups were compared, no statistical difference was found in terms of age, gender, body mass index, range of motion, Constant score, VAS score, glenoid cartilage stepping, and bone defect (p>0.05). The operation time was longer in the iliac crest bone graft transfer group compared to the Latarjet group (p<0.05). Latarjet and iliac crest bone graft transfer can be used successfully in the treatment of bony Bankart in recurrent anterior shoulder dislocations. The operation time is longer in iliac crest bone graft transfer compared to the Latarjet procedure.

Paper 41: Does MR Arthrography Improve Evaluation of Patients with Posterior Shoulder Instability? An Analysis from the MOON Shoulder Instability Group

Objectives: Posterior shoulder instability is an uncommon injury, accounting for 2-12% of shoulder instability patients. Magnetic resonance imaging (MRI) is often utilized to non-invasively evaluate the joint for labral, cartilage, and bony injury. MR arthrography (MRA) may improve the evaluation of these intra-articular structures, but requires additional cost, time, and an invasive procedure. Moreover, its benefits for patients with posterior shoulder instability are unclear. Accurate imaging is critical in patients undergoing surgery because certain findings may influence the surgical approach. Thus, the purpose of this study is to compare the accuracy of MRA and non-enhanced MRI in detecting labral, chondral, and osseous lesions in patients with posterior shoulder instability. Methods: There were 291 patients with unilateral posterior shoulder instability who had preoperative MRA or MRI between 2006 and 2021 in the MOON database. Images were reviewed by a fellowship-trained musculoskeletal radiologist with 10+ years of experience and an orthopaedic surgeon. Evaluators were blinded to age, gender, medical history, MR report, and arthroscopic findings, but were aware of the patient's history of posterior shoulder instability. Examinations were evaluated for presence, location, morphology, and length of glenoid labral tears. Tear length and localization were noted using a standard clock face. The presence and size of humeral/glenoid osseous and cartilage lesions was also noted.Intraoperative findings from arthroscopic evaluation were documented by the surgeon using a standard response questionnaire. Diagnostic performance of standard MRA and MRI were evaluated using sensitivity and specificity with arthroscopic evaluation as the gold-standard. Chi-squared or Fisher’s exact tests were used to compare the sensitivities and specificities of MRA and MRI. Significance was defined as P &lt; 0.05. Results: 200 patients (69%) had MRA, while 91 patients had non-contrast MRIs of the shoulder. On imaging evaluation, 273 (94%) patients had labral tears with a mean tear size of 156º. 39 (13%) patients had humeral cartilage lesions, whereas 40 (14%) patients had glenoid cartilage lesions. 34 (12%) patients had glenoid bone loss greater than 5%. The mean glenoid bone loss was 12% (range, 5% - 26%). A reverse Hill-Sachs lesion was present in 35 (12%) patients. 16 (6%) patients had bipolar bone loss. The sensitivity for detection of labral tears was high for both MRA (0.95) and standard MRI (0.98) (Tables 1 and 2), though the specificity was low for both modalities (0.25 and 0.40, respectively). There was no difference in the sensitivities or specificities of the two imaging modalities in the detection of labral tears. MRA had a lower sensitivity than MRI in the detection of glenoid cartilage lesions (0.31 vs 0.88, p &lt; 0.001), but no difference was observed for specificity. There was no difference in the sensitivities and specificities of MRA and MRI for humeral cartilage lesions (p = 0.354).MRA had a higher sensitivity than MRI in assessing glenoid bone loss (0.78 vs 0.50, p &lt; 0.001), though there was no difference in specificity. There was no difference between imaging modalities in the evaluation of humeral bone loss (p = 1.000). Conclusions: In this multicenter study, MRA was the most commonly utilized preoperative advanced imaging study for patients with posterior shoulder instability. MRA had a higher sensitivity in detecting glenoid bone loss but lower sensitivity in detecting glenoid cartilage lesions compared to standard non-contrast MRI. There was no difference in diagnostic performance between MRA and MRI in the diagnosis of labral tears and humeral chondral and osseous lesions. MRA may provide an advantage over standard MRI in the evaluation of glenoid bone loss, which can influence the treatment plan for patients undergoing surgical management of posterior shoulder instability.

ArUco-based stylus reliability for reproductible 3D digitalisation of shoulder cartilage contours.

Imaging techniques in anatomy have developed rapidly over the last decades through the emergence of various 3D scanning systems. Depending on the dissection level, non-contact or tactile contact methods can be applied on the targeted structure. The aim of this study was to assess the inter and intra-observer reproducibility of an ArUco-based localisation stylus, that is, a manual technique on a hand-held stylus. Ten fresh-frozen, unembalmed adult arms were used to digitalise the glenoid cartilage related to the glenohumeral joint and the contour of the clavicle cartilage related to the acromioclavicular joint. Three operators performed consecutive digitalisations of each cartilage contour using an ArUco-based localisation stylus recorded by a single monocular camera. The shape of each cartilage was defined by nine shape parameters. Intra-observer repeatability and inter-observer reproducibility were computed using an intra-class correlation (ICC) for each of these parameters. Overall, 35.2 ± 2.4 s and 26.6 ± 10.2 s were required by each examiner to digitalise the contour of a glenoid and acromioclavicular cartilage, respectively. For most parameters, good-to-excellent agreements were observed concerning intra-observer (ICC ranging between 0.81 and 1.00) and inter-observer (ICC ranging between 0.75 and 0.99) reproducibility. To conclude, through a fast and versatile process, the use of an ArUco-based localisation stylus can be a reliable low-cost alternative to conventional imaging methods to digitalise shoulder cartilage contours.

Comparison of conventional MR arthrography and 3D volumetric MR arthrography in detection of cartilage defects accompanying glenoid labrum pathologies.

In this study, we aimed to compare conventional and T1-weighted volumetric magnetic resonance arthrography (MRA) in the diagnosis and grading of glenoid cartilage defects that accompany labral pathologies. A total of 79 patients who were prediagnosed with labrum pathologies based on shoulder magnetic resonance imaging (MRI) had MRA and CTA between December 2021 and May 2022. CTA was regarded as reference standard. CTA images were examined by a radiologist experienced in musculoskeletal radiology, and MRA images were examined by two radiologists independently to determine presence, grade, and localization of any glenoid cartilage defect, if present. Sensitivity, specificity, and accuracy were calculated separately for conventional and T1-weighted volumetric MRA. In addition, at the last stage, two observers examined all MRAs together, and the presence of a cartilage defect was decided by consensus, and the overall sensitivity, specificity, and accuracy were calculated. Cartilage defect was detected on CTAs of 48 (60.75%) cases of among 79 patients with labrum pathology. The sensitivity, specificity, and accuracy of conventional MRA for two examiners were 17-19%, 100-100%, and 49-51%, respectively, while those values were 67-65%, 92-97%, and 84-77%, respectively, for T1-weighted volumetric MRA. Inter-examiner agreement was excellent for diagnosis of cartilage defects on all MRAs. The overall sensitivity, specificity, and accuracy for detection of glenoid cartilage lesions by MRA were 69%, 97%, and 80%, respectively. T1-weighted volumetric MRA seems to demonstrate cartilage defects accompanied with labrum pathologies accurately with high sensitivity, specificity, and excellent inter-examiner agreement.

ARTHROSCOPIC AND RADIOLOGICAL FINDINGS AT TIME OF LATARJET SCREW REMOVAL

The Latarjet procedure is a well described method to stabilize anterior shoulder instability. There are concerns of high complication rates, one of these being a painful shoulder without instability due to screw irritation. The arthroscopic changes in the shoulder at time of screw removal compared to those pre-Latarjet have not been described in the literature.We conducted a retrospective review of arthroscopic videos between 2015 and 2022 of 17 patients at the time of their Latarjet screw removal and where available (n=13) compared them to arthroscopic findings at time of index Latarjet. Instability was an exclusion criterion. X-rays prior to screw removal were assessed independently by two observers blinded to patient details for lysis of the graft. Arthroscopic assessment of the anatomy and pathological changes were made by two shoulder surgeons via mutual consensus. An intraclass correlation coefficient (ICC) was analyzed as a measure for the inter-observer reliability for the radiographs.Our cohort had an average age of 21.5±7.7 years and an average period of 16.2±13.1 months between pre- and post-arthroscopy. At screw removal all patients had an inflamed subscapularis muscle with 88% associated musculotendinous tears and 59% had a pathological posterior labrum. Worsening in the condition of subscapularis muscle (93%), humeral (31%) and glenoid (31%) cartilage was found when compared to pre-Latarjet arthroscopes. Three failures of capsular repair were seen, two of these when only one anchor was used. X-ray review demonstrated 79% of patients had graft lysis. Excellent inter-rater reliability was observed with an ICC value of 0.82.Our results show a high rate of pathological change in the subscapularis muscle, glenoid labrum and articular cartilage in the stable but painful Latarjet. 79% of patients had graft lysis with prominent screws on X-ray.

Favorable short-term outcomes of micronized allogenic cartilage scaffold for glenoid cartilage defects associated with posterior glenohumeral instability

To determine clinical outcomes associated with micronized allogenic cartilage scaffold use for treatment of posterior glenoid cartilage defects at 2 years. Case series. A retrospective analysis of prospectively collected data was performed on a consecutive series of patients who underwent arthroscopic treatment of a symptomatic posterior glenoid cartilage defect with micronized allogenic cartilage scaffold between January 2019 and December 2020. The primary outcome was subjective shoulder value (SSV) at latest follow-up. Secondary outcomes included visual analog scale (VAS), recurrence of instability, and range of motion (ROM). Seven patients, including 4 in the setting of primary posterior instability and 3 in the setting of recurrent symptoms after arthroscopic posterior glenohumeral stabilization, were included in the analysis with a mean follow up of 2.6 years (range, 2-3.7 years). Statistically significant improvements were seen in SSV (median= 40, interquartile range [IQR]= 40-50 before surgery; vs median= 85, IQR= 67.5-87.5 after surgery; P= .018) and VAS (median= 4, IQR= 4-6.3 before surgery; vs median=1, IQR= 0-1.5 after surgery; P= .010). No significant differences were seen in ROM. There were no cases of recurrent instability or reoperation. The use of micronized allogenic cartilage scaffold for glenoid cartilage defects is associated with clinical improvement at 2-year follow-up. This is the case when performed in conjunction with index posterior labral repair when there is a concomitant glenoid cartilage defect or when performed in the setting of persistent pain and mechanical symptoms after prior posterior labral repair. Level IV, therapeutic case series.

Arthroscopic posterior capsulolabral repair grants adequate outcomes in shoulders with posterior instability without glenoid cartilage lesions.

Posterior capsulolabral repair (posterior Bankart) is effective to restore shoulder stability and relieve pain, though a recent meta-analysis reported recurrent instability in 9.5% of patients, and that only 62.7% were able to resume sports. The purpose of this study was to assess the outcomes of arthroscopic posterior capsulolabral repair in a population of unselected patients, in terms of recurrence of instability, clinical scores, and return to sports. The authors retrospectively studied a consecutive series of 22 patients that underwent posterior capsulolabral repair between 2009 and 2019. Patients were assessed before posterior capsulolabral repair and at a minimum follow-up of 24months, in terms of subjective shoulder value (SSV), Western Ontario Shoulder Instability Index (WOSI), as well as level of sport. Following surgery, all complications, reoperations or episodes of instability were noted. The cohort comprised 21 men (95%) and 1 woman (5%), aged 38.8 ± 12.5years (range 17-61) at index surgery. Of the 20 patients that performed sports, only 2 (10%) stopped sports after surgery, while 18 resumed their main sport (90%). At a follow-up of 65.4 ± 34.8months (range 25-146), the SSV was 85.1 ± 14.7, pain on VAS was 1.9 ± 2.1, and the Constant-Murley score was 71.6 ± 17.9. Five patients had subjective instability without dislocation (23%). Nine patients (41%) had no pain (0 points), 6 patients (27%) had mild pain (1-2 points), 4 patients (18%) had moderate pain (3 points), while 3 patients (14%) had severe pain (5-8 points). Arthroscopic posterior capsulolabral repair prevented recurrent dislocation in patients with posterior shoulder instability at a minimum follow-up of 2years, despite persistent pain in 32%, and subjective instability in 23%. These complications were mainly observed in patients with work-related accidents and glenoid cartilage lesions. III, case series.

Paper 57: Can 2.0mm Diameter Operative Arthroscopy Predict Appropriate Surgical Management of Intra-Articular Shoulder Pathology More Accurately than MRI? A Prospective, Blinded Clinical Trial

Objectives: The purpose of this study was to compare the intra-articular diagnostic capability of a 2.0mm needle arthroscope to that obtained using MR imaging in patients scheduled to undergo shoulder arthroscopy and determine which was more effective at predicting the appropriate surgical procedure (as defined by CPT code) for patients with glenohumeral pathology. Methods: This study is a prospective, blinded, single-center trial performed with patients who were scheduled to undergo operative arthroscopy for intra-articular shoulder pathology. Thirty consecutive patients were included between May 2020 and July 2020. Each patient underwent an MRI pre- operatively and, on the day of surgery, two recorded diagnostic arthroscopies were performed: the first using a 2.0mm arthroscope, followed by a standard 4.0mm arthroscope. Both videos and MR images were then de-identified and blindly reviewed by two fellowship-trained orthopedic sports surgeons. Analysis included diagnostic agreement of the 2.0mm arthroscope and MRI as compared to the 4.0mm arthroscope which was considered the gold standard. The descriptive quality of the intra-articular pathology as well as the most appropriate treatment recommendation in the form of Current Procedural Terminology (CPT) was compared between the diagnostic modalities. Results: For all intra-articular pathologies except humeral head chondromalacia, the 2.0mm arthroscope had a higher percentage agreement and positive predictive value (PPV) compared to MRI. The 2.0mm arthroscope had a higher sensitivity, specificity, PPV and negative predictive value (NPV) when evaluating the long-head biceps (LHB), superior labrum, infraspinatus, subscapularis and glenoid cartilage. The 2.0mm arthroscope had the highest accuracy when identifying lesions of the LHB (Kappa 0.73) followed by tears of the subscapularis (Kappa 0.65), and articular-sided lesions of the supraspinatus (Kappa 0.62). MRI accuracy was highest when identifying lesions of the LHB (Kappa 0.52), followed by tears of the subscapularis (Kappa 0.31), and articular-sided supraspinatus lesions (Kappa 0.29) but these values were all lower in the MRI group when compared to the 2.0mm arthroscope group. When predicting the appropriate CPT codes for each shoulder, the 2.0mm group had a higher kappa value than the MRI group (kappa 0.87 v 0.56) and a higher agreement percentage (93.1% v 76.7%) (p=0.0003). When considering rotator cuff repair (CPT 29827), the 2.0mm arthroscopy was equally sensitive (93.3 and 93.8) but had a higher PPV as compared to MRI (100 and 83.3). There were no complications related to the use of the 2.0mm arthroscope in this series. Conclusions: 2.0mm arthroscopy is a safe and effective method of diagnosing intra-articular glenohumeral pathology. When diagnosing pathology within the shoulder, the 2.0mm arthroscopy had a higher positive predictive value than MRI when assessing all anatomic pathology except for humeral head chondromalacia. When compared to MRI, the 2.0mm arthroscope was able to more accurately predict which rotator cuff tears would require surgical repair (CPT 29827). When considering all CPT codes for the shoulders in this series, the 2.0mm arthroscope was more accurate at predicting the appropriate surgical procedure (CPT) than the MRI. [Table: see text][Table: see text]

The Influence of Glenoid Bone Loss and Graft Positioning on Graft and Cartilage Contact Pressures After the Latarjet Procedure

Background: Glenohumeral joint contact loading before and after glenoid bone grafting for recurrent anterior instability remains poorly understood. Purpose: To develop a computational model to evaluate the influence of glenoid bone loss and graft positioning on graft and cartilage contact pressures after the Latarjet procedure. Study Design: Controlled laboratory study. Methods: A finite element model of the shoulder was developed using kinematics, muscle and glenohumeral joint loading of 6 male participants. Muscle and joint forces at 90° of abduction and external rotation were calculated and employed in simulations of the native shoulder, as well as the shoulder with a Bankart lesion, 10% and 25% glenoid bone loss, and after the Latarjet procedure. Results: A Bankart lesion as well as glenoid bone loss of 10% and 25% significantly increased glenoid and humeral cartilage contact pressures compared with the native shoulder (P < .05). The Latarjet procedure did not significantly increase glenoid cartilage contact pressure. With 25% glenoid bone loss, the Latarjet procedure with a graft flush with the glenoid and the humerus positioned at the glenoid half-width resulted in significantly increased humeral cartilage contact pressure compared with that preoperatively (P = .023). Under the same condition, medializing the graft by 1 mm resulted in humeral cartilage contact pressure comparable with that preoperatively (P = .097). Graft lateralization by 1 mm resulted in significantly increased humeral cartilage contact pressure in both glenoid bone loss conditions (P < .05). Conclusion: This modeling study showed that labral damage and greater glenoid bone loss significantly increased glenoid and humeral cartilage contact pressures in the shoulder. The Latarjet procedure may mitigate this to an extent, although glenoid and humeral contact loading was sensitive to graft placement. Clinical Relevance: The Latarjet procedure with a correctly positioned graft should not lead to increased glenohumeral joint contact loading. The present study suggests that lateral graft overhang should be avoided, and in the situation of large glenoid bone defects, slight medialization (ie, 1 mm) of the graft may help to mitigate glenohumeral joint contact overloading.

Pyrocarbon hemiarthroplasty of the shoulder: a systematic review and meta-analysis of clinical results.

Hemiarthroplasty is often considered in the setting of preserved glenoid cartilage given the high risk of revision associated with total shoulder arthroplasty. Pyrocarbon (PyC) has been used as an implant material that theoretically allows for formation of a neo-membrane that would act like cartilage to reduce glenoid wear. The purpose of this study was to evaluate the clinical outcomes, radiographic outcomes, revision rates, and complication rates in the existing literature on shoulder hemiarthroplasty using PyC. The MEDLINE, Embase, and Scopus databases were searched for articles relating to shoulder hemiarthroplasty using the terms "pyrocarbon" or "pyrolytic carbon." Abstracts and articles were screened against predefined inclusion and exclusion criteria, with a minimum of 24 months' follow-up required. Data on patient demographic characteristics, clinical outcome scores, complications, revision rates, and radiographic findings were recorded. Where appropriate, meta-analysis was performed. Twelve studies were selected for final inclusion, with a total of 536 patients. Among the studies reporting preoperative and postoperative range of motion (ROM), an overall improvement in ROM was observed. The mean Constant score was 70.9 points postoperatively, with a mean improvement of 36.2 points (n=359, 9 studies). Radiographically, 22.8% of patients (n=536, 8 studies) had evidence of glenoid erosion, 10.4% had changes in implant positioning, and 9.9% had tuberosity thinning. In addition, 1.5% of patients had radiographic subacromial space reduction, whereas 0.7% had an increase in tuberosity thickness. Across all studies, there was an 8.6% complication rate, with the most common cause being glenoid erosion (2.6%, n=14). There was an overall 7.7% revision rate (n=41), with 63% of revisions (n=26) undergoing conversion to reverse or total shoulder arthroplasty. PyC hemiarthroplasty shows overall improvements in ROM and patient-reported outcomes for patients. However, there remains concern for glenoid erosion on radiographic evaluation at minimum 2-year follow-up. Although preliminary studies have shown encouraging results, this systematic review emphasizes the need for longer-term follow-up studies with further radiographic evaluation of the severity of glenoid erosion and the association with functional outcomes and failure risk.

Cementless Metal-Free Ceramic-Coated Shoulder Resurfacing.

Shoulder resurfacing is a versatile, bone-conserving procedure to treat arthritis, avascular necrosis, and rotator cuff arthropathy. Shoulder resurfacing is of interest to young patients who are concerned about implant survivorship and those in need of a high level of physical activity. Using a ceramic surface reduces wear and metal sensitivity to clinically unimportant levels. Between 1989 and 2018, 586 patients received cementless, ceramic-coated shoulder resurfacing implants for arthritis, avascular necrosis, or rotator cuff arthropathy. They were followed for a mean of 11 years and were assessed using the Simple Shoulder Test (SST) and Patient Acceptable Symptom State (PASS). CT scans were used in 51 hemiarthroplasty patients to assess the glenoid cartilage wear. Seventy-five patients had a stemmed or stemless implant in the contralateral extremity. A total of 94% of patients had excellent or good clinical results and 92% achieved PASS. 6% of patients required a revision. A total of 86% of patients preferred their shoulder resurfacing prosthesis over a stemmed or stemless shoulder replacement. The glenoid cartilage wear at a mean of 10 years was 0.6 mm by a CT scan. There were no instances of implant sensitivity. Only one implant was removed due to a deep infection. Shoulder resurfacing is an exacting procedure. It is clinically successful, with excellent long-term survivorship in young and active patients. The ceramic surface has no metal sensitivity, very low wear, and, therefore, it is successful as a hemiarthroplasty.

Gene Expression in Glenoid Articular Cartilage Varies Across Acute Instability, Chronic Instability, and Osteoarthritis.

Shoulder instability is a common pathology associated with an elevated risk of osteoarthritis (OA). Little is known about gene expression in the cartilage of the glenohumeral joint after dislocation events, particularly as it relates to the risk of posttraumatic OA. This study tested the hypothesis that gene expression in glenoid cartilage varies among acute instability (<3 dislocations), chronic instability (≥3 dislocations), and OA. Articular cartilage was collected from the anteroinferior glenoid of consenting patients undergoing shoulder stabilization surgery (n = 17) or total shoulder arthroplasty (n = 16). Digital quantitative polymerase chain reaction was used to assess the relative expression of 57 genes (36 genes from OA risk allele studies, 21 genes from differential expression studies), comparing (1) OA versus instability (acute and chronic combined), (2) acute versus chronic instability, (3) OA versus acute instability, and (4) OA versus chronic instability. The expression of 11 genes from OA risk allele studies and 9 genes from differential expression studies was significantly different between cartilage from patients with instability and those with OA. Pro-inflammatory genes from differential expression studies and genes from OA risk allele studies were more highly expressed in cartilage in the OA group compared with the instability group, which expressed higher levels of extracellular matrix and pro-anabolic genes. The expression of 14 genes from OA risk allele studies and 4 genes from differential expression studies, including pro-inflammatory genes, anti-anabolic genes, and multiple genes from OA risk allele studies, was higher in the acute instability group compared with the chronic instability group. Cartilage in the OA group displayed higher expression of CCL3, CHST11, GPR22, PRKAR2B, and PTGS2 than cartilage in the group with acute or chronic instability. Whereas cartilage in both the acute and chronic instability groups had higher expression of collagen genes, cartilage in the OA group had expression of a subset of genes from OA risk allele studies or from differential expression studies that was lower than in the acute group and higher than in the chronic group. Glenoid cartilage has an inflammatory and catabolic phenotype in shoulders with OA but an anabolic phenotype in shoulders with instability. Cartilage from shoulders with acute instability displayed greater (cellular) metabolic activity compared with shoulders with chronic instability. This exploratory study identified genes of interest, such as CCL3, CHST11, GPR22, PRKAR2B, and PTGS2, that have elevated expression in osteoarthritic glenoid cartilage. These findings provide new biological insight into the relationship between shoulder instability and OA, which could lead to strategies to predict and potentially modify patients' risk of degenerative arthritis due to shoulder instability.

Evaluation of articular cartilage wear against pyrolytic carbon in the context of spherical interposition shoulder arthroplasty

Metal shoulder hemiarthroplasty is known to cause failure due to glenoid cartilage erosion. Pyrolytic carbon (PyC), a non-metallic biomaterial, may be an attractive alternative due to its good general tribological characteristics and biocompatibility. We investigated the in vitro biotribological properties of PyC articulated against living cartilage for use as spherical shoulder interposition implant. The evaluation includes a comparison with the typically used cobalt‑chromium‑molybdenum alloy (CoCrMo) and zirconia toughened alumina (ZTA), a more recent biomaterial for hemiarthroplasty. The rate of cartilage degradation was assessed by means of cartilage wear biomarkers (glycosaminoglycans and hydroxyproline) in lubricant and histological changes of the cartilage superficial zone. In addition, the percentage of cell viability and metabolic activity of chondrocytes was assessed. The data revealed that PyC has similar tribological performance in terms of cell viability, cell metabolic activity, and tissue degradation compared to ZTA. Although not significant, CoCrMo affected chondrocyte metabolism and induced a thinner superficial layer with structural defects. There was a combined adsorption of phospholipids and biomarkers on the biomaterials; sGAGs adsorbed between 23 and 43% of the total concentration, and the adsorption rate of phospholipids increased significantly with friction. Biomaterial analysis is required to obtain the full picture of cartilage biomarker release and lubrication mechanisms. Our results suggest that PyC has good tribological performance and compares well with established biomaterials for hemiarthroplasty. It supports the use of PyC in spherical shoulder interposition implant as a viable alternative to conventional metal hemiarthroplasty. Further evaluation of the clinical performance of PyC is required.

Development of a New Model of Humeral Hemiarthroplasty in Rats

Purpose In vivo models are anatomically comparable to humans allowing to reproduce the patterns and progression of the disease and giving the opportunity to study the symptoms and responses to new treatments and materials. This study aimed to establish a valid and cost-effective in vivo rat model to assess the effects of implanted shoulder hemiarthroplasty materials on glenoid articular cartilage wear. Methods Eight adult male Wistar rats underwent right shoulder hemi-arthroplasty. A stainless steel metal bearing was used as a shoulder joint prosthesis. X-rays were performed one week after surgery to verify correct implant position. Additional X-rays were performed 30 and 60 days post-implantation. Animals were sacrificed 24 weeks after implantation. All specimens were evaluated with micro-CT for cartilage and bone wear characteristics as well as histologically for signs of osteoarthritis. Samples were compared to the non-operated shoulders. Results All animals recovered and resumed normal cage activity. All X-rays demonstrated correct implant positioning except for one in which the implant was displaced. Histologic evaluation demonstrated arthritic changes in the implanted shoulder. Decreased Trabecular thickness and Trabecular Spacing were documented among the implanted parties (p < .05). Bone Mineral Density and Tissue Mineral Density were reduced in the operated shoulder although not significantly (p = .07). Conclusions This study demonstrated significant glenoid cartilage wearing in the operated shoulder. Furthermore, the presence of an intra-articular hemiarthroplasty implant diminished underlying glenoid bone quality. This novel, in vivo-model will enable researchers to test implant materials and their effects on cartilage and bone tissue in a cost-effective reproducible rat model.

A numerical study of the contact geometry and pressure distribution along the glenoid track

The glenoid track geometry and the contact forces acting on the glenohumeral joint at static positions of 30°, 60°, 90° and 120° of abduction with 90° of external rotation were evaluated using a finite element model of the shoulder that, differently from most usual approximations, accounts the humeral head translations and the deformable-to-deformable non-spherical joint contact. The model was based on data acquired from clinical exams of a single subject, including the proximal humerus, scapula, their respective cartilages concerning the glenohumeral joint, and the rotator cuff and deltoid muscles. The forces acting on the glenohumeral joint were estimated using a simulation framework consisting of an optimization procedure allied with finite element analysis that seeks the minimum muscle forces that stabilize the joint. The joint reaction force magnitude increases up to 680.25N at 90° of abduction and decreases at further positions. From 60° onward the articular contact remains at the anterior region of the glenoid cartilage and follows an inferior to superior path at the posterior region of the humeral head cartilage. The maximum contact pressure of 3.104MPa occurs at 90° abduction. Although translating inferiorly throughout the movement, the projection of the humeral head center at the glenoid plane remains at the central region of the glenoid surface. The model results qualitatively matched the trends observed in the literature and supports the consideration of the translational degrees of freedom to evaluate the joint contact mechanics.

Glenohumeral osteoarthritis: what the surgeon needs from the radiologist.

Glenohumeral osteoarthritis (GHOA) is a widely prevalent disease with increasing frequency due to population aging. Both clinical manifestations and radiography play key roles in the initial diagnosis, staging, and management decisions. Radiographic disease progression evaluation is performed using validated staging systems, such as Kellgren and Lawrence, Samilson, and Hamada. For young patients with mild to moderate GHOA and failed conservative treatment, arthroscopic preservation surgery (APS) is usually considered. Older patients and those with severe GHOA benefit from different types of arthroplasties. Preoperative magnetic resonance imaging (MRI) is essential for APS surgical planning, as it maps repairable labral, cartilage, and rotator cuff lesions. For arthroplasty planning, the status of glenoid cartilage and intactness of rotator cuff as well as glenoid morphology represent key factors guiding the decision regarding the most suitable hardware design, whether resurfacing, partial, total, or reverse joint replacement. Pre-surgical MRI or alternatively computed tomography arthrogram is employed to evaluate the cartilage and rotator cuff. Finally, three-dimensional computed tomography (3D CT) is indicated to optimally assess the glenoid morphology (to determine Walch classification, version, inclination, and bone loss) and analyze the necessity for glenoid osteotomy or graft augmentation to correct the glenoid structural abnormalities for future success and longevity of the shoulder implants or chosen constructs. Understanding the purpose of each imaging and treatment modality allows more efficient image interpretation. This article reviews the above concepts and details what a surgeon needs from a radiologist and could benefit from accurate reporting of preoperative imaging studies.

Bullseye: preclinical evaluation of a novel structured light-based imaging workflow to inform glenoid implant positioning in total shoulder arthroplasty

BackgroundAccurate glenoid component positioning during total shoulder arthroplasty (TSA) is critical for prosthesis longevity and postoperative function. Glenoid component positioning in many TSA procedures depends on the insertion of a guide pin through the glenoid vault. However, up to 48% of TSA procedures involve guide pin malpositioning. The aim of this study was to evaluate the ability of a novel structured light imaging system to visualize glenoid guide pin position and trajectory in surgically exposed cadaveric shoulders. Computed tomography (CT)-based and magnetic resonance imaging (MRI)-based workflows and subchondral bone–based and glenoid cartilage–based workflows were compared. MethodsPreoperative cone-beam CT (CBCT) and MRI images were acquired for 5 intact cadaveric shoulders. Following deltopectoral surgical exposure, a glenoid vault guide pin was inserted through the glenoid vault of each scapula as in a clinical TSA procedure. A 3D printed optical tracker was placed over the guide pin, and a 3D optical surface image of the glenoid and tracker was acquired using a handheld structured light sensor. A postprocedural CBCT was acquired for each shoulder to verify guide pin position and trajectory. The imaging procedure was repeated after débridement of the glenoid cartilage to expose subchondral bone. The guide pin was segmented from the postprocedural CBCT image (actual guide pin). A virtual model of the tracker was aligned with a co-linear representation of the intraoperative guide pin (predicted guide pin). A series of image registrations aligned the actual and predicted guide pin positions to yield visualization accuracy, defined as the trajectory and offset errors between predicted and actual guide pins. ResultsThe mean guide pin trajectory and offset errors based on the subchondral bone were 2.22 ± 1.27° and 1.27 ± 0.46 mm for the CT-based workflow and 2.27 ± 1.72° and 1.78 ± 0.92 mm for the MRI-based workflow, respectively. Registration of the cartilage surface models visualized in the MRI images reduced accuracy to a trajectory error of 3.89 ± 1.57° (P = .147) and offset error of 2.28 ± 1.33 mm (P = .217). ConclusionThe Bullseye structured light imaging system presented an accurate approach for glenoid guide pin verification and adjustment during TSA using preoperative MRI or CT. Future development for the implementation of the Bullseye system should focus on improving surface segmentations and automation of the computer vision algorithm needed to facilitate clinical translation.