Articular cartilage thickness of the humeral head: an anatomic study

The degenerated glenohumeral joint

Aims

This study aimed to define the histopathology of degenerated humeral head cartilage and synovial inflammation of the glenohumeral joint in patients with omarthrosis (OmA) and cuff tear arthropathy (CTA). Additionally, the potential of immunohistochemical tissue biomarkers in reflecting the degeneration status of humeral head cartilage was evaluated.

Methods

Specimens of the humeral head and synovial tissue from 12 patients with OmA, seven patients with CTA, and four body donors were processed histologically for examination using different histopathological scores. Osteochondral sections were immunohistochemically stained for collagen type I, collagen type II, collagen neoepitope C1,2C, collagen type X, and osteocalcin, prior to semiquantitative analysis. Matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 levels were analyzed in synovial fluid using enzyme-linked immunosorbent assay (ELISA).

Results

Cartilage degeneration of the humeral head was associated with the histological presentation of: 1) pannus overgrowing the cartilage surface; 2) pores in the subchondral bone plate; and 3) chondrocyte clusters in OmA patients. In contrast, hyperplasia of the synovial lining layer was revealed as a significant indicator of inflammatory processes predominantly in CTA. The abundancy of collagen I, collagen II, and the C1,2C neoepitope correlated significantly with the histopathological degeneration of humeral head cartilage. No evidence for differences in MMP levels between OmA and CTA patients was found.

Conclusion

This study provides a comprehensive histological characterization of humeral cartilage and synovial tissue within the glenohumeral joint, both in normal and diseased states. It highlights synovitis and pannus formation as histopathological hallmarks of OmA and CTA, indicating their roles as drivers of joint inflammation and cartilage degradation, and as targets for therapeutic strategies such as rotator cuff reconstruction and synovectomy.

Finite element analysis part 1 of 2: Influence of short stem implant polyethylene configuration on glenohumeral joint biomechanics

Purpose

Stress shielding in short-stem arthroplasty can cause critical metaphyseal bone loss. If the size and shape of the humeral shaft are important factors, it is unknown whether the shape of the polyethylene component in reverse shoulder arthroplasty (RSA) affects bone stress around or within the stem. We explored the impact of polyethylene shape on humeral and scapular stress distribution using a finite element model.

Methods

We developed a shoulder-specific finite element model. A defined set of muscle forces was applied to simulate movements. An intact rotator cuff state and a superior deficient rotator cuff state were modelled. We used the FX V135 short stem in three conditions: total shoulder arthroplasty (TSA), and RSA with symmetrical and asymmetrical polyethylene (145°/135°). We measured biomechanical markers related to bone stress for different implant sizes. Joint kinematics and the mechanical behaviour of the implant were compared.

Results

Rupture of the supraspinatus muscle produced a functionally limited shoulder. The placement of an anatomic TSA with an intact rotator cuff restored function similar to that of a healthy shoulder. RSA in the rotator cuff-deficient shoulder restored function regardless of stem size and polyethylene shape. While stem size had an impact on the stress distribution in the bone and implant, it did not show significant potential for increasing or decreasing overall stress. For the same stem, stress distribution at the humerus is different between TSA and RSA. Polyethylene shape did not alter the transmission of stress to the bone in RSA. Asymmetric polyethylene produced a greater abduction range of motion.

Conclusions

In terms of bone stress distribution, smaller stems seemed more appropriate for TSA, while larger stems may be more appropriate for RSA. Polyethylene shape resulted in different ranges of motion but did not influence bone stress.

Level of Evidence

Diagnostic Tests or Criteria; Level IV.

Effect of patient-specific scapular morphology on the glenohumeral joint force and shoulder muscle force equilibrium: a study of rotator cuff tear and osteoarthritis patients

Introduction: Osteoarthritis (OA) and rotator cuff tear (RCT) pathologies have distinct scapular morphologies that impact disease progression. Previous studies examined the correlation between scapular morphology and glenohumeral joint biomechanics through critical shoulder angle (CSA) variations. In abduction, higher CSAs, common in RCT patients, increase vertical shear force and rotator cuff activation, while lower CSAs, common in OA patients, are associated with higher compressive force. However, the impact of the complete patient-specific scapular morphology remains unexplored due to challenges in establishing personalized models. Methods: CT data of 48 OA patients and 55 RCT patients were collected. An automated pipeline customized the AnyBody™ model with patient-specific scapular morphology and glenohumeral joint geometry. Biomechanical simulations calculated glenohumeral joint forces and instability ratios (shear-to-compressive forces). Moment arms and torques of rotator cuff and deltoid muscles were analyzed for each patient-specific geometry. Results and discussion: This study confirms the increased instability ratio on the glenohumeral joint in RCT patients during abduction (mean maximum is 32.80% higher than that in OA), while OA patients exhibit a higher vertical instability ratio in flexion (mean maximum is 24.53% higher than that in RCT) due to the increased inferior vertical shear force. This study further shows lower total joint force in OA patients than that in RCT patients (mean maximum total force for the RCT group is 11.86% greater than that for the OA group), attributed to mechanically advantageous muscle moment arms. The findings highlight the significant impact of the glenohumeral joint center positioning on muscle moment arms and the total force generated. We propose that the RCT pathomechanism is related to force magnitude, while the OA pathomechanism is associated with the shear-to-compressive loading ratio. Overall, this research contributes to the understanding of the impact of the complete 3D scapular morphology of the individual on shoulder biomechanics.

Arthroscopic Minced Cartilage Repair in the Glenohumeral Joint - Short Term Clinical Outcome in a 33-Year-Old Handyman: A Case Report

Objective

Clinical outcome data for the novel minced cartilage procedure are sparse. While good results have been shown for the knee joint, this is the first report in the current literature regarding this increasingly important procedure in the glenohumeral joint.

Case Description

A 33-year-old handyman with a cartilage defect in the humeral head underwent an all arthroscopic one-stage cartilage repair with the AutoCartTM procedure (Arthrex GmbH, Munich, Germany). A senior specialist examined the patient before surgery, five-, 12-and 24-weeks post-surgery. Outcome parameters (Constant-Murley Score, UCLA Shoulder Score and ASES Score) and radiographic imaging were recorded.

Results

At six months, follow-up the outcome parameter showed excellent results, the joint pain decreased to numeric rating scale (NRS) 0. The postoperative magnetic resonance imaging (MRI) revealed a thin cartilage layer in the treated area with sufficient integration to the surrounding tissue. The cartilage in the former defect zone presented a homogeneous signal, which was comparable to the intact cartilage.

Conclusion

This case report underlines the growing interest in single-stage arthroscopic minced cartilage procedures and shows promising results in the glenohumeral joint. Yet, larger investigations with long-term follow-up are necessary to provide reliable clinical data to determine if comparable results can be achieved over time.

Glenohumeral Cartilage Thickness: Implications in Prosthetic Design and Osteochondral Allograft Transplantation

OBJECTIVE

A complete understanding of the glenohumeral joint anatomy is crucial for osteochondral allograft (OCA) transplantation and prosthetic design. However, existing data on the cartilage thickness distribution are not consistent. This study aims to describe the cartilage thickness distribution at both the glenoid cavity and humeral head in males and females.

DESIGN

Sixteen fresh cadaveric shoulder specimens were dissected and separated to expose the glenoid and humeral head articular surfaces. The glenoid and humeral head were cut into 5-mm coronal sections. Sections were imaged and cartilage thickness was measured at 5 standardized points on each section. Measurements were analyzed based on age, sex, and regional location.

RESULTS

For the humeral head, cartilage was thickest centrally (M = 1.77 ± 0.35 mm) and thinnest superiorly and inferiorly (M = 1.42 ± 0.37 mm, 1.42 ± 0.29 mm). At the glenoid cavity, cartilage was thickest in the superior and inferior areas (M = 2.61 ± 0.47 mm, 2.53 ± 0.58 mm) and thinnest centrally (M = 1.69 ± 0.22 mm). Males were found to have thicker cartilage at both the humeral head and glenoid (P = 0.0014, P = 0.0133).

CONCLUSIONS

Articular cartilage thickness distribution of the glenoid and humeral head is nonuniform and reciprocal in nature. These results can be used to further inform prosthetic design and OCA transplantation. We noted a significant difference in cartilage thickness between males and females. This suggests that the sex of the patient should be taken into consideration when matching donors for OCA transplantation.

A Validated Open-Source Shoulder Finite Element Model and Investigation of the Effect of Analysis Precision

Understanding the loads and stresses on different tissues within the shoulder complex is crucial for preventing joint injury and developing shoulder implants. Finite element (FE) models of the shoulder joint can be helpful in describing these forces and the biomechanics of the joint. Currently, there are no validated FE models of the intact shoulder available in the public domain. This study aimed to develop and validate a shoulder FE model, then make the model available to the orthopaedic research community. Publicly available medical images of the Visible Human Project male subject's right shoulder were used to generate the model geometry. Material properties from the literature were applied to the different tissues. The model simulated abduction in the scapular plane. Simulated glenohumeral (GH) contact force was compared to in vivo data from the literature, then further compared to other in vitro experimental studies. Output variable results were within one standard deviation of the mean in vivo experimental values of the GH contact force in 0°, 10°, 20°, 30°, and 45° of abduction. Furthermore, a comparison among different analysis precision in the Abaqus/Explicit platform was made. The complete shoulder model is available for download at github.com/OSEL-DAM/ShoulderFiniteElementModel.

Influence of Graft Positioning during the Latarjet Procedure on Shoulder Stability and Articular Contact Pressure: Computational Analysis of the Bone Block Effect

The Latarjet procedure is the most popular surgical procedure to treat anterior glenohumeral (GH) instability in the presence of large anterior glenoid bone defects. Even though the placement of the bone graft has a considerable influence on its efficacy, no clear indications exist for the best graft position. The aim of this study was to investigate the influence of the medial-lateral positioning of the bone graft on the contact mechanics and GH stability due to the bone block effect. Four finite element (FE) models of a GH joint, with a 20% glenoid bone defect, treated by the Latarjet procedure were developed. The FE models differed in the medial-lateral positioning of the bone graft, ranging from a flush position to a 4.5 mm lateral position with respect to the flush position. All graft placement options were evaluated for two separate shoulder positions. Anterior GH instability was simulated by translating the humeral head in the anterior direction, under a permanent compressive force, until the peak translation force was reached. Joint stability was computed as the ratio between the shear and the compressive components of the force. The lateralization of the bone graft increased GH stability due to the bone block effect after a 3 mm lateralization with respect to the flush position. The increase in GH stability was associated with a concerning increase in peak contact pressure due to the incongruous contact between the articulating surfaces. The sensitivity of the contact pressures to the medial-lateral positioning of the bone graft suggests a trade-off between GH stability due to the bone block effect and the risk of osteoarthritis, especially considering that an accurate and consistent placement of the bone graft is difficult in vivo.

Biomechanical, Morphological, and Biochemical Characteristics of Articular Cartilage of the Ovine Humeral Head

OBJECTIVE

Shoulder pain is commonly attributed to rotator cuff injury or osteoarthritis. Ovine translational models are used to investigate novel treatments aimed at remedying these conditions to prevent articular cartilage degeneration and subsequent joint degradation. However, topographical properties of articular cartilage in the ovine shoulder are undefined. This study investigates the biomechanical, morphological, and biochemical attributes of healthy ovine humeral head articular cartilage and characterizes topographical variations between surface locations.

DESIGN

Ten humeral heads were collected from healthy skeletally mature sheep and each was segregated into 4 quadrants using 16 regions of interest (ROIs) across the articular surface. Articular cartilage of each ROI was analyzed for creep indentation, thickness, and sulfated glycosaminoglycan (sGAG) and collagen quantity. Comparisons of each variable were made between quadrants and between ROIs within each quadrant.

RESULTS

Percent creep, thickness, and sGAG content, but not collagen content, were significantly different between humeral head quadrants. Subregion analysis of the ROIs within each surface quadrant revealed differences in all measured variables within at least one quadrant. Percent creep was correlated with sGAG (r = -0.32, P = 0.0001). Collagen content was correlated with percent creep (r = 0.32, P = 0.0009), sGAG (r = -0.19, P = 0.049), and thickness (r = -0.19, P = 0.04).

CONCLUSIONS

Topographical variations exist in mechanical, morphologic, and biochemical properties across the articular surface of the ovine humeral head. Recognizing this variability in ovine humeral head cartilage will provide researchers and clinicians with accurate information that could impact study outcomes.

Biologic Characteristics of Shoulder Articular Cartilage in Comparison to Knee and Ankle Articular Cartilage From Individual Donors

OBJECTIVE

To describe histological and metabolic characteristics of glenohumeral joint (GHJ) articular cartilage and compare to knee and ankle joints.

DESIGN

Macroscopically healthy human humeral head, glenoid, knee, and ankle articular cartilage were obtained from tissue donors (N = 16, 9 males, 7 females; age 45-78 years), within 24 hours of death. Gross morphology of each joint was assessed using Collins grading. Cartilage explants were removed from the entire surface of each joint, cultured for 48 hours with or without interleukin-1β and processed for histology with Safranin O, proteoglycan (PG) synthesis/content, and polymerase chain reaction for collagen II, aggrecan, and SOX9. Results were compared between uncultured and cultured controls and across all 3 joints.

RESULTS

Structural differences were seen on histology between GHJ cartilage and knee and ankle cartilage of the same Collins grade, specifically, depletion of Safranin O staining in the extracellular matrix. Treatment of glenoid and humerus specimens with IL-1β demonstrated a trend toward decreased PG synthesis in each explant but this decrease did not reach significance. There was no significant difference in PG synthesis between humerus, glenoid, knee, and ankle samples at baseline, day-0 control, 48-hour control, and 48 hours after treatment with 0.1 ng or 10 ng of IL-1β. There were no significant increases in collagen II, SOX9, and aggrecan expression in glenoid and humeral head cartilage samples treated with IL-1β compared to baseline controls.

CONCLUSIONS

GHJ articular cartilage did not significantly differ from ankle or knee cartilage with regard to PG synthesis and gene expression. However, it did differ in its histological appearance in normal state.

Interobserver agreement for detecting Hill-Sachs lesions on magnetic resonance imaging

BACKGROUND

Our aim is to determine the interobserver reliability for surgeons to detect Hill-Sachs lesions on magnetic resonance imaging (MRI), the certainty of judgement, and the effects of surgeon characteristics on agreement.

METHODS

Twenty-nine patients with Hill-Sachs lesions or other lesions with a similar appearance on MRIs were presented to 20 surgeons without any patient characteristics. The surgeons answered questions on the presence of Hill-Sachs lesions and the certainty of diagnosis. Interobserver agreement was assessed using the Fleiss' kappa (κ) and percentage of agreement. Agreement between surgeons was compared using a technique similar to the pairwise t-test for means, based on large-sample linear approximation of Fleiss' kappa, with Bonferroni correction.

RESULTS

The agreement between surgeons in detecting Hill-Sachs lesions on MRI was fair (69% agreement; κ, 0.304; p<0.001). In 84% of the cases, surgeons were certain or highly certain about the presence of a Hill-Sachs lesion.

CONCLUSIONS

Although surgeons reported high levels of certainty for their ability to detect Hill-Sachs lesions, there was only a fair amount of agreement between surgeons in detecting Hill-Sachs lesions on MRI. This indicates that clear criteria for defining Hill-Sachs lesions are lacking, which hampers accurate diagnosis and can compromise treatment.

Synovial Fluid Fatty Acid Profiles Are Differently Altered by Inflammatory Joint Pathologies in the Shoulder and Knee Joints

Anomalies of fatty acid (FA) metabolism characterize osteoarthritis (OA) and rheumatoid arthritis (RA) in the knee joint. No previous study has investigated the synovial fluid (SF) FA manifestations in these aging-related inflammatory diseases in the shoulder. The present experiment compared the FA alterations between the shoulder and knee joints in patients with end-stage OA or end-stage RA. SF samples were collected during glenohumeral or knee joint surgery from trauma controls and from OA and RA patients (n = 42). The FA composition of SF total lipids was analyzed by gas chromatography with flame ionization and mass spectrometric detection and compared across cohorts. The FA signatures of trauma controls were mostly uniform in both anatomical locations. RA shoulders were characterized by elevated percentages of 20:4n-6 and 22:6n-3 and with reduced proportions of 18:1n-9. The FA profiles of OA and RA knees were relatively uniform and displayed lower proportions of 18:2n-6, 22:6n-3 and total n-6 polyunsaturated FAs (PUFAs). The results indicate location- and disease-dependent differences in the SF FA composition. These alterations in FA profiles and their potential implications for the production of PUFA-derived lipid mediators may affect joint lubrication, synovial inflammation and pannus formation as well as cartilage and bone degradation and contribute to the pathogeneses of inflammatory joint diseases.

Assessment of Safe Cartilage Harvesting Quantity in the Shoulder: A Cadaveric Study

Purpose

To evaluate the volume and yield of morselized cartilage that can be harvested from the shoulder for immediate reimplantation and repair.

Methods

A standard arthroscopic approach was used to harvest non–load-bearing cartilage from 5 cadaveric shoulder specimens. Cartilage was separated from the humerus, grasped, added to the cartilage particulator, and morselized to form a cartilage paste. The volume of reclaimed cartilage was measured and compared with average humeral and glenoid defects.

Results

The total yield of cartilage paste following tissue processing that was obtained from the 5 glenohumeral joints ranged from 1.0 mL to 2.4 mL with a mean volume of 1.9 ± 0.5 mL, yielding a theoretical 18.6 cm² ± 5.2 cm² of coverage with a 1-mm monolayer. Previously reported mean glenoid defect size ranges from 1.12 cm² to 2.73 cm², while the mean humeral defect size ranges from 4.22 cm² to 6.00 cm².

Conclusions

This study validated that through a single-stage surgical and processing technique it is possible to obtain a sufficient volume for re-implantable autologous morselized cartilage graft to address most glenohumeral articular cartilage defects.

Clinical Relevance

Chondrocyte grafts have been shown to be effective in cartilage repair. A single-site, single-staged procedure that uses a patient’s autologous shoulder cartilage from the same joint has the potential to reduce morbidity associated with multiple surgical sites, multistaged procedures, or nonautologous tissue in shoulder surgery.

Geometric analysis of the humeral head and glenoid in the Indian population and its clinical significance

BACKGROUND

Total anatomic and reverse shoulder prostheses are designed to match the dimensions of the native bony anatomy. Chinese and Japanese bony dimensions of the shoulder have been found to be different from that of the Caucasian population. We hypothesized that the geometric dimensions of the humeral head and glenoid in the Indian population would also be different from that of the Caucasian population.

METHOD

Fifty patients underwent computerized tomographic scans of their normal shoulders. We calculated the superoinferior (SI) diameter of the humeral head, anteroposterior diameter of the humeral head, radius of curvature of the humeral head, humeral head retroversion, humeral head thickness, inclination angle, critical shoulder angle, greater tuberosity angle, glenoid width, glenoid length, radius of curvature of the glenoid, glenoid inclination angle, and glenoid version.

RESULTS

The radius of curvature of the humeral head averaged 22.9 ± 1.7 mm, the articular surface thickness 17.1 ± 1.6 mm, and the SI diameter 42.3 ± 3 mm. The SI diameter strongly correlated with the thickness (r = 0.617, P = .001). The anteroposterior/SI articular surface diameter ratio averaged 0.9 ± 0.9, the articular surface thickness/radius of curvature ratio 0.7 ± 0.9, the inclination angle 133.8 ± 6.4, and the retroversion angle 33.5° ± 8.5°. The radius of curvature of the glenoid averaged 23.3 ± 3.4 mm, the glenoid width 24.0 ± 2 mm, the SI length 31.3 ± 2.2 mm, the glenoid inclination angle 78.7° ± 4.8°, and the glenoid retroversion 1.8° ± 3.8°.

DISCUSSION

Compared with the Western population, our cohort had a smaller humeral radius of curvature (P = .04), smaller articular surface diameter (P = .001), smaller inclination angle (P = .003), larger retroversion angle of the humeral head (P < .001), and smaller glenoid length and width (P < .0001). Most of the implant companies did not have smaller sized combinations of humeral heads with thickness to match our population. The glenoid width of females in our cohort was found to be smaller for the smallest size of the glenoid base plate.

CONCLUSION

Smaller sized options in humeral head diameter and thickness of the anatomic prosthesis and glenoid baseplate of the reverse shoulder prosthesis need to be made available to suit our population and avoid a mismatch.

Internal Derangement of the Shoulder Joint in Asymptomatic Professional Baseball Players

RATIONALE AND OBJECTIVES

To evaluate the influence of throwing activity on shoulder morphology and the difference in shoulder morphology on MRI between asymptomatic professional baseball players and volunteers who play baseball as a recreational activity.

MATERIALS AND METHODS

This retrospective case-control study included 68 asymptomatic professional baseball players (32 pitchers, 36 batters) and 30 male volunteers. Morphologic changes in the following shoulder structures were assessed on MRI: rotator cuff, glenoid labrum, humeral head, subacromial-subdeltoid bursa, subcoracoid bursa, long head of the biceps tendon, deltoid muscle, acromion, and clavicle.

RESULTS

Partially torn supraspinatus, posterior glenoid or labral lesions, bone marrow edema, intraosseous cysts of the humeral head, and edematous subacromial-subdeltoid bursa were significantly more commonly observed in players (p = 0.01, p < 0.001, p = 0.03, p< 0.001, and p < 0.001). Players with more than 10 years of experience had a significantly higher incidence of patchy intermediate signal abnormality (odds ratio: 3.73, p = 0.03), partial tear in the supraspinatus tendon (odds ratio: 6.20, p = 0.03), and edematous change in the subacromial-subdeltoid bursa (odds ratio: 2.96, p = 0.03).

CONCLUSION

The results from our study showed that repetitive throwing activities cause macroscopic structural lesions of the shoulder joints in asymptomatic baseball players. Significance of these lesions is to be determined.

A Biomechanical and Structural Comparison of Articular Cartilage and Subchondral Bone of the Glenoid and Humeral Head

Background:

The underlying cause of glenohumeral arthritis is poorly understood. Glenohumeral arthrosis patterns have been classified and described, and differential contact stresses within the joint have been implicated as a cause of joint degeneration, but the intrinsic cause of degeneration patterns in the glenohumeral joint (GHJ) remains largely unknown.

Purpose/Hypothesis:

The purpose of this study was to assess morphological and mechanical differences in articular cartilage (AC) and subchondral bone (SCB) of the glenoid and humeral head in matched cadaveric specimens. We hypothesized that there would be significant zone-dependent differences between the intrinsic characteristics (AC thickness, SCB thickness, compressive forces) of the glenoid and humeral head.

Study Design:

Descriptive laboratory study.

Methods:

Ten human cadaveric GHJs (mean age, 60.2 years) were dissected to expose articular surfaces to facilitate biomechanical testing. A 2-mm and 6-mm osteochondral plug was harvested at 5 zones (central, anterior, posterior, inferior, superior) on the glenoid and humeral head (N = 200 plugs). Each 2-mm core was histologically sectioned and stained with hematoxylin and eosin. AC thickness measurements were taken using light microscopy. The 6-mm plugs were imaged using micro–computed tomography to measure SCB thickness. After imaging, AC specimens were removed from the SCB and tested in confined compression. The compressive aggregate modulus (H_A0), compressive stiffening coefficient (β), and compressive modulus at 16% strain (H_A0.16) and at 50% strain (H_A0.50) were calculated.

Results:

The overall AC thickness was significantly greater on the glenoid. The glenoid also had significantly thicker AC at the inferior, posterior, and superior zones as well as significantly higher SCB thickness overall and significantly greater SCB thickness at the anterior and central zones. The glenoid had significantly greater overall H_A0.50 and H_A0.50 values at the superior zone and had a significantly greater overall compressive stiffening coefficient (β).

Conclusion:

The glenoid had thicker AC, thicker SCB, and greater compressive stiffness at high strain.

Clinical Relevance:

These intrinsic differences may help better elucidate the cause of differential degeneration patterns between the glenoid and humeral head.

Optimal management of glenohumeral osteoarthritis

Glenohumeral osteoarthritis (OA) is defined as progressive loss of articular cartilage, resulting in bony erosion, pain, and decreased function. This article provides a gross overview of this disease, along with peer-reviewed research by experts in the field. The pathology, diagnosis, and classification of this condition have been well described. Treatment begins with non-operative measures, including oral and topical anti-inflammatory agents, physical therapy, and intra- articular injections of either a corticosteroid or a viscosupplementation agent. Operative treatment is based on the age and function of the affected patient, and treatment of young individuals with glenohumeral OA remains controversial. Various methods of surgical treatment, ranging from arthroscopy to resurfacing, are being evaluated. The roles of hemiarthroplasty, total shoulder arthroplasty, and reverse shoulder arthroplasty are similarly reviewed with supporting data.

[Shoulder cartilage regeneration : Indications, possibilities, surgical implementation]

Asymptomatic cartilage lesions of the shoulder are frequent. Symptomatic lesions are treated analogously to other hyaline cartilage bearing joints and can be treated arthroscopically in the vast majority of cases. The therapeutic options can be subdivided into resection, stimulation and transplantation of the defect cartilage. There are only a few reports about outcome after cartilage restoration surgery in the literature, and microfracturing is the surgical technique that has been most investigated.

Computer Modeling Analysis of the Talar Dome as a Graft for the Humeral Head

PURPOSE

To study the degree of surface congruency between the talar dome and humeral head, to determine the size of graft harvestable from the talar dome, and to determine if there are surrogate markers that correspond to a higher degree of surface congruency.

METHODS

Computer models of 7 nonmatched humeral heads and 7 talar domes were generated by digital segmentation of magnetic resonance (MR) images. Modeled defect regions of each humeral head were then aligned with medial and lateral surfaces of each talar dome using software to maximally limit surface mismatch. Modeled defect sizes ranging from 24 × 10 mm to 30 × 10 mm were tested. Congruence match of <1 mm separation was then measured.

RESULTS

The average surface match between randomly selected talar domes to humeral head surfaces was 87.2% when 1 mm was selected as the maximal acceptable congruence difference. Congruence match was not affected by graft size or laterality of talar dome as source of graft. Matching radius of curvature of talar dome to humeral head and height of donor to recipient correlated with improved congruence match. Under best match conditions, a maximal congruence match of 95.2% was achieved.

CONCLUSIONS

The present study indicates that the talar dome can be a potential source of osteochondral allograft for Hill-Sachs lesions with a maximal defect size of 30 × 10 mm for a single graft. Larger graft sizes resulted in decreased success of actual graft harvest as a result of dimensional constraints of the talar dome. Additional studies are required to determine the biomechanical compatibility of this graft.

CLINICAL RELEVANCE

The talar dome has a high degree of surface congruency in comparison with the humeral head though the maximal graft size harvestable limits its clinical applicability.

Three-dimensional anthropometric analysis of the glenohumeral joint in a normal Japanese population

BACKGROUND

An understanding of normal glenohumeral geometry is important for anatomical reconstruction in shoulder arthroplasty. Unfortunately, the details of the glenohumeral joint in Asian populations have not been sufficiently evaluated. The purpose of this study was to evaluate the 3-dimensional geometry of the glenohumeral joint in the normal Japanese population and to clarify its morphologic features.

METHODS

Anthropometric analysis of the glenohumeral joint was performed using computed tomography scans of 160 normal shoulders from healthy Japanese volunteers. The glenohumeral dimensions and orientation were analyzed 3-dimensionally. Sex differences and correlations between sides and among the respective parameters in the glenohumeral dimensions were evaluated.

RESULTS

The normal Japanese humeral head has an average width of 41.4 mm, thickness of 13.2 mm, diameter of 42.9 mm, retroversion of 32°, and inclination of 135°. The glenoid has an average height of 31.5 mm, width of 23.1 mm, diameter of 62.0 mm, retroversion of 0°, and inferior inclination of 2°. The values of the glenohumeral dimensions were uniform in men and women, and the humeral head and glenoid were larger in men than in women. The glenohumeral size was well correlated between the 2 sides, and there were direct correlations among the heights, humeral length, humeral head size, and glenoid size.

CONCLUSIONS

The present study revealed the glenohumeral geometry in the normal Japanese population. The present results would be useful to determine the size of implants and to improve the design of shoulder prostheses that reflect the normal anatomy of the Asian glenohumeral joint.

Articular cartilage and local anaesthetic: A systematic review of the current literature

BACKGROUND

Chondrolysis involves the breakdown of cartilage following arthroscopic surgery, most commonly affecting the glenohumeral joint.

METHODS

This review summarises all clinical and laboratory studies regarding local anaesthetic (LA) and its association with chondrolysis. We identified 289 papers, 41 of which met our inclusion criteria and were included in the final review.

RESULTS

Bupivacaine, lidocaine, ropivacaine and levobupivacaine are all toxic to cartilage. Intra-articular infusions confer a greater toxicity to cartilage than single injections.

CONCLUSIONS

Intra-articular LA pain pumps carry a high risk of chondrolysis and should be avoided. Further studies are indicated to assess long-term single exposure LA implications.

Knee chondrolysis by infusion of bupivacaine with epinephrine through an intra-articular pain pump catheter after arthroscopic ACL reconstruction

BACKGROUND

Postoperative knee chondrolysis caused by continuous intra-articular pain pumps infusing bupivacaine with epinephrine is a rare but serious complication.

PURPOSE

To determine the association between postoperative intra-articular infusion of bupivacaine with epinephrine and the development of knee chondrolysis in patients who have undergone arthroscopic anterior cruciate ligament reconstruction (ACLR). The authors hypothesized that the development of knee chondrolysis after ACLR is associated with postoperative high-dose intra-articular bupivacaine with epinephrine infusion.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

In this retrospective cohort study, the charts of all patients treated with arthroscopic ACLR by a single surgeon between January 1, 2004, and December 31, 2006, were reviewed. Patients with severe articular cartilage damage at the time of the index procedure, with known knee joint infection, inflammatory arthritis, multiligament knee injury, bilateral knee injury, or any previous knee surgery, were excluded. Patients were grouped into 2 cohorts: the exposure group (those who had postoperative infusion of bupivacaine with epinephrine via an intra-articular pain pump [IAPP]) and the nonexposure group (those without postoperative infusion).

RESULTS

A total of 105 patients met the inclusion and exclusion criteria. There were 57 male and 48 female patients with a mean age at surgery of 25.5 ± 8.6 years (range, 13-52 years). The exposure group consisted of 46 patients and the control group of 59 patients. Thirteen of 46 patients (28.3%) who received an IAPP developed chondrolysis. There were no cases of chondrolysis in the control group. Of those in the exposure group, 32 patients were exposed to 0.5% bupivacaine with epinephrine and 12 developed chondrolysis (37.5%), while 14 patients were exposed to 0.25% bupivacaine with epinephrine and 1 developed chondrolysis (7.1%). Patients exposed to 0.5% bupivacaine with epinephrine had a significantly higher incidence of chondrolysis compared with those exposed to 0.25% (P = .03). Patients with chondrolysis had severe pain and limitations in daily activity.

CONCLUSION

The development of knee chondrolysis was associated with the intra-articular infusion of bupivacaine with epinephrine postoperatively. Furthermore, the presented evidence suggests that this occurs in a dose-dependent manner. The risk of knee chondrolysis might be reduced by avoidance of intra-articular infusion of bupivacaine with epinephrine. We recommend against continuous intra-articular infusion of local anesthetic postoperatively.

Effect of humeral head rotation on bony glenohumeral stability

BACKGROUND

The humeral head and glenoid cavity are not perfectly spherical, nor do they have matching radii of curvature. We hypothesized that glenohumeral stability is dependent on axial humeral rotation.

METHODS

Seven cadaveric shoulders were investigated. For each test, the humeral head was translated relative to the glenoid in 2 directions (starting from neutral), anterior and anteroinferior. Contact forces and lateral humeral displacement were recorded. Joint stability was quantified using the stability ratio and energy to dislocation. The humerus was set in 60° of abduction for all tests. Testing was performed in neutral rotation and 60° of external rotation.

FINDINGS

The force displacement curves differed between rotations. In both displacement directions, the peak translational force occurred with less displacement in neutral rotation than in external rotation. The stability ratio and energy to dislocation in the anteroinferior direction were greater than in the anterior direction for both rotation positions. While there were no significant differences in the stability ratio or energy to dislocation between rotation conditions at complete dislocation, the energy required to move the humeral head 10% of the glenoid width was significantly greater with the arm in neutral rotation.

INTERPRETATION

The energy to dislocation, a new parameter of dislocation risk, and the stability ratio, indicate that the glenohumeral joint is more stable in the anteroinferior direction than the anterior direction. During initial displacement, axial rotation of the humeral head contributes to glenohumeral geometrical stability. However, humeral head rotation does not have a significant effect when looking at complete dislocation.

Management of cartilage defects in the shoulder

Articular cartilage lesions of the glenohumeral joint are an especially difficult clinical problem to manage, particularly in the younger, more active patient. Left untreated, these lesions may progress in the long-term, leading to further pain and disability. While shoulder arthroplasty remains a viable option in older patients with glenohumeral arthritis, concerns over component longevity and loosening in younger patients make it less attractive in that age group. Arthroscopic joint debridement with loose body removal, often with capsular release, has been successful in select, more sedentary patients. More recent techniques, including autologous chondrocyte implantation (ACI), osteochondral grafting (allograft versus autograft), interpositional arthroplasty, and microfracture surgery, have been evaluated for use in the shoulder. These procedures have experienced success in weight bearing joints, including the knee and ankle. Despite the good clinical results in the shoulder with short-term follow-up reported in some small series, the treatment of chondral injuries in the glenohumeral joint remains a challenging problem.

Glenohumeral joint preservation: a review of management options for young, active patients with osteoarthritis

The management of osteoarthritis of the shoulder in young, active patients is a challenge, and the optimal treatment has yet to be completely established. Many of these patients wish to maintain a high level of activity, and arthroplasty may not be a practical treatment option. It is these patients who may be excellent candidates for joint-preservation procedures in an effort to avoid or delay joint replacement. Several palliative and restorative techniques are currently optional. Joint debridement has shown good results and a combination of arthroscopic debridement with a capsular release, humeral osteoplasty, and transcapsular axillary nerve decompression seems promising when humeral osteophytes are present. Currently, microfracture seems the most studied reparative treatment modality available. Other techniques, such as autologous chondrocyte implantation and osteochondral transfers, have reportedly shown potential but are currently mainly still investigational procedures. This paper gives an overview of the currently available joint preserving surgical techniques for glenohumeral osteoarthritis.

Comparison of third toe joint cartilage thickness to that of the finger proximal interphalangeal (PIP) joint to determine suitability for transplantation in PIP joint reconstruction

PURPOSE

To compare the cartilage thickness of the third toe joints to the finger proximal interphalangeal (PIP) joints to assess the appropriateness of using third toe osteochondral grafts for finger PIP joint reconstruction.

METHODS

A laser scanner was used to construct 3-dimensional computer models of 6 matched cadaver right third toe PIP joints, condyles of the third toe middle phalanx, and finger PIP joints with and without cartilage. Cartilage distribution patterns were computed and analyzed for each surface. The cartilage thickness of both sides of the third toe PIP joint and the third toe middle phalanx condyles were compared to the PIP joint of the fingers. A total of 18 third toe and 48 finger joint surfaces were analyzed.

RESULTS

For the third toe middle phalanx condyles, the mean thickness was 0.20 ± 0.09 mm with a maximum of 0.52 ± 0.18 mm, and a coefficient of variation (CV%; a measure of uniformity of cartilage distribution) of 62. For the third toe proximal phalanx condyles, the mean cartilage thickness was 0.26 ± 0.10 mm with a maximum thickness of 0.56 ± 0.14 mm and a CV% of 44. The mean thickness, maximum thickness, and CV% of the finger proximal phalanx condyles was 0.43 ± 0.11 mm, 0.79 ± 0.16 mm, and 31, respectively. For the third toe middle phalanx base, the mean thickness was 0.28 ± 0.06 mm with a maximum of 0.47 ± 0.09 mm and a CV% of 34, compared to the finger middle phalanx base mean of 0.40 ± 0.12 mm with a maximum of 0.67 ± 0.14 mm and a CV% of 27.

CONCLUSIONS

There were significant differences in cartilage thickness between the third toe and the fingers in this study. However, fewer differences were observed with the third toe middle phalanx base cartilage thickness than with the third toe condyles in comparison to the fingers.