Glenohumeral contact pressure in a simulated active compression test using cadaveric shoulders

Physical Examination Maneuvers for SLAP Lesions: A Systematic Review and Meta-analysis of Individual and Combinations of Maneuvers

BACKGROUND

Superior labrum anterior to posterior (SLAP) lesions are targeted on physical examination using a variety of provocative maneuvers.

PURPOSE/HYPOTHESIS

The purpose was to conduct a systematic review on the performance of physical examination maneuvers in diagnosing SLAP lesions and to perform a meta-analysis comparing the sensitivity and specificity of these examinations both individually and in combination. The null hypothesis stated that there would be no significant difference in the sensitivity or specificity of the included physical examination tests, neither individually nor in combination.

STUDY DESIGN

Meta-analysis and systematic review; Level of evidence, 4.

METHODS

A systematic review was performed with the inclusion criteria of studies that reported either the sensitivities and specificities or the number of true-positive, true-negative, false-positive, or false-negative results for at least 1 maneuver for identifying SLAP lesions. A meta-analysis was performed to determine the sensitivity and specificity of individual maneuvers. Additional analysis determined the performance of these maneuvers when combined in series and parallel. In series, all must be present to be considered positive. In parallel, any single positive test forces the overall combination to be considered positive. Only tests that were included in ≥3 studies were considered in the meta-analysis and those included in ≥4 studies were considered in the combination analysis.

RESULTS

Overall, 862 studies were identified, 18 of which were included in the systematic review and meta-analysis. The physical examinations included were the O'Brien (n = 16), speed (n = 8), Yergason (n = 6), anterior slide (n = 8), crank (n = 7), Jobe (n = 5), dynamic labral shear (n = 3), Kim 2 (n = 3), and biceps groove tenderness tests (n = 3). All combinations of 2 to 5 maneuvers in both series and parallel were considered. The O'Brien and crank test combination was the most sensitive 2-test combination in both parallel and series. The Yergason and anterior slide test combination was the most specific 2-test combination in parallel and series.

CONCLUSION

This systematic review and meta-analysis reports an updated meta-analysis considering the sensitivity and specificity of common physical examination maneuvers used in the diagnosis of SLAP lesions and considers these values for tests in both series and parallel combinations. The present analysis demonstrates improved specificities when tests are considered in series and improved sensitivities when considered in parallel combination.

Contact Mechanics of Elliptical and Spherical Head Implants during Axial Rotation in Anatomic Total Shoulder Arthroplasty: A Biomechanical Comparison

BACKGROUND

Elliptical humeral head implants have been proposed to result in more anatomic kinematics following total shoulder arthroplasty (aTSA). The purpose of this study was to compare glenohumeral contact mechanics during axial rotation using spherical and elliptical humeral head implants in the setting of aTSA.

METHODS

Seven fresh-frozen cadaveric shoulders were utilized for biomechanical testing in neutral (NR), internal (IR), and external (ER) rotation at various levels of abduction (0°, 15°, 30°, 45°, 60°) with lines of pull along each of the rotator cuff muscles. Each specimen underwent the following three conditions: (1) native, and TSA using (2) an elliptical and (3) spherical humeral head implant. Glenohumeral contact mechanics, including contact pressure (CP; kPa), peak contact pressure (PCP; kPa), and contact area (CA; mm2), were measured in neutral rotation as well as external and internal rotation using a pressure mapping sensor.

RESULTS

Elliptical head implants showed a significantly lower PCP in ER compared to spherical implants at 0° (Δ-712.0 kPa; p = 0.034), 15° (Δ-894.9 kPa; p = 0.004), 30° (Δ-897.7 kPa; p = 0.004), and 45° (Δ-796.9 kPa; p = 0.010) of abduction, while no significant difference was observed in ER at 60° of abduction or at all angles in NR and IR. Both implant designs had similar CA in NR, ER, and IR at all tested angles of abduction (p > 0.05, respectively).

CONCLUSIONS

In the setting of aTSA, elliptical heads showed significantly lower PCP during ER at 0° to 45° of abduction, when compared to spherical head implants. However, in NR and IR, PCP was similar between implant designs. Both designs showed similar CA during NR, ER, and IR at all abduction angles.

LEVEL OF EVIDENCE

basic science; controlled laboratory study.

Superior Capsular Reconstruction Partially Restores Native Glenohumeral Joint Loads In A Dynamic Biomechanical Shoulder Model

PURPOSE

To evaluate the effect of an irreparable posterosuperior rotator cuff tear (PSRCT) on glenohumeral joint loads and to quantify improvement following superior capsular reconstruction (SCR) using an acellular dermal allograft.

METHODS

Ten fresh-frozen cadaveric shoulders were tested using a validated dynamic shoulder simulator. A pressure mapping sensor was placed between the humeral head and glenoid surface. Each specimen underwent the following conditions: (1) native, (2) irreparable PSRCT, (3) SCR using a 3mm-thick acellular dermal allograft. Glenohumeral abduction angle (gAA) and superior humeral head migration (SM) were measured using 3D motion tracking software. Cumulative deltoid force (cDF) and glenohumeral contact mechanics, including contact area (gCA) and contact pressure (gCP), were assessed at rest,15°,30°,45°, and maximum angle of glenohumeral abduction.

RESULTS

The PSRCT resulted in a significant decrease of gAA along with an increase in SM, cDF, and gCP (P<.001, respectively). SCR did not restore native gAA (P<.001), however, SM was significantly reduced (P<.001). Further, SCR significantly reduced deltoid forces at 30° (P=.007) and 45° of abduction (P=.007) when compared to the PSRCT. SCR did not restore native cDF at 30°(P=.015), 45°(P<.001), and maximum angle (P<.001) of glenohumeral abduction. Compared to the PSRCT, SCR resulted in a significant decrease of gCP at 15°(P=.008), 30°(P=.002), and 45°(P=.006). However, SCR did not completely restore native gCP at 45° (P=.038) and maximum abduction angle (P=.014).

CONCLUSION

In this dynamic shoulder model, SCR only partially restored native glenohumeral joint loads. However, SCR significantly decreased glenohumeral contact pressure, cumulative deltoid forces, and superior migration, while increasing abduction motion, when compared to the posterosuperior rotator cuff tear.

CLINICAL RELEVANCE

These observations raise concerns regarding the true joint preserving potential of SCR for an irreparable posterosuperior rotator cuff tear, along with its ability to delay progression of cuff tear arthropathy and eventual conversion to reverse shoulder arthroplasty.

The O'Brien test demonstrates a higher diagnostic value in identifying posteroinferior labral tears than superior labral anterior to posterior (SLAP) tears

Background

The primary aim was to determine the diagnostic value of the O'Brien test in localizing labral tears of the shoulder.

Methods

A consecutive series of patients electing for labral repair between January 2005 and March 2021 were included in this retrospective study. Inclusion criteria were as follows: (1) any patient with a labral tear who was elected for arthroscopic labral repair and (2) had documentation of the O'Brien test in the preoperative evaluation. Exclusion criteria were patients that had a negative arthrographically enhanced computed tomography or magnetic resonance imaging scan. During arthroscopy, the localization and extension of the labral tear was documented in a standardized 12-o'clock configuration. Anteroinferior, posteroinferior, superior labrum anterior to posterior (SLAP), and combined labral tears were documented. The sensitivity, specificity, positive and negative predictive values, accuracy, positive and negative likelihood ratios, receiver operating characteristic curve, and area under the curve were calculated to determine the diagnostic value.

Results

The cohort consisted of 271 patients (77% male) and included 105 anteroinferior, 86 posteroinferior, 46 SLAP, and 32 combined parts of the labrum. The mean age at time of surgery was 30 (±10.2) years. The O'Brien test was positive in 142 (52%) patients and showed the highest sensitivity and specificity for the posteroinferior tears (83% and 62%) compared to the anteroinferior (16% and 25%), combined labral parts (69% and 50%), and SLAP (65% and 50%) tears. In addition, receiver operating characteristic-analysis demonstrated a significantly higher area under the curve for posteroinferior tears compared to the other tears (P < .001).

Conclusion

The O'Brien test demonstrates more diagnostic value for posteroinferior tears than other labral tears. This includes the SLAP tear, for which the O'Brien test was originally designed.

Clinical Relevance

These findings are helpful towards reinterpreting the O'Brien test as well as diagnosing, and more specifically localizing labral tears in clinics.

Increased Glenohumeral Joint Loads Due to a Supraspinatus Tear Can Be Reversed With Rotator Cuff Repair: A Biomechanical Investigation

PURPOSE

To evaluate the effect of an isolated full-thickness supraspinatus (SSP) tear on glenohumeral kinematics and contact mechanics, as well as to quantify improvement following rotator cuff repair (RCR).

METHODS

Ten fresh-frozen cadaveric shoulders (mean age: 63.1 ± 4.6 years) were tested using a dynamic shoulder simulator. A pressure-mapping sensor was placed between the humeral head and the glenoid. Each specimen underwent the following three conditions: 1) native, 2) isolated full-thickness SSP tear, and 3) RCR. Maximum abduction angle (MAA) and superior humeral head migration (SHM) were measured using 3D motion tracking software. Cumulative deltoid force (CDF) and glenohumeral contact mechanics, including contact area (GCA) and contact pressure (GCP), were assessed at the resting position, as well as at 15°, 30°, 45°, and 60° of glenohumeral abduction.

RESULTS

Compared to native, the SSP tear resulted in a significant decrease in MAA (Δ-8.3°; P < .001) along with a SHM of 6.4 ± 3.8 mm, while significantly increasing CDF (Δ20.5 N; P = .008), GCP (Δ63.1 kPa; P < .001), and peak GCP (Δ278.6 kPa; P < .001), as well as decreasing GCA (Δ-45.8 mm²; P < .001) at each degree of abduction. RCR reduced SHM to 1.2 ± 2.5 mm, while restoring native MAA, CDF (Δ1.8 N), GCA (Δ4.5 mm²), GCP (Δ-4.5 kPa) and peak GCP (Δ19.9 kPa) at each degree of abduction (P > .999, respectively).

CONCLUSION

In a dynamic biomechanical cadaveric model, increased glenohumeral joint loads due to a full-thickness SSP tear can be reversed with RCR. More specifically, RCR restored native glenohumeral contact area and contact pressure, while preventing superior humeral head migration and decreasing compensatory deltoid forces.

CLINICAL RELEVANCE

These time 0 observations indicate that undergoing rotator cuff repair may prevent the development of degenerative changes by significantly reducing glenohumeral joint loads and ensuring sufficiently stable joint kinematics.

Reinterpretation of O'Brien test in posterior labral tears of the shoulder

Background:

Injuries to the posterior labrum are less common and more difficult to diagnose compared to anterior labral pathology. This may be in part due to difficulties in preoperative diagnosis. Posterior labral injuries cause abnormal loading of the rotator cuff with subsequent weakness. Examination using the O'Briens test tightens the posterior capsule and posteriorly translates the humeral head, stressing the labrum resulting in pain and weakness.

Method:

A retrospective study.

Results:

Of 74 patients diagnosed with a posterior labral tear at arthroscopy 55 had subjective weakness on performing a O'Briens test, a sensitivity of 83% and a positive predictive value (PPV) of 90%.

Conclusion:

Multiple tests have been described for posterior labral pathology and none of these, on their own, have a high sensitivity rate. Posterior labral injuries can often be missed on magnetic resonance imaging scanning and also at surgery if not specifically looked for. Using a sign of clinically demonstrated weakness when performing the O'Briens test, and hence reinterpretation of the test, is sensitive, with a high PPV for posterior labral pathology and can help guide further treatment.

Glenohumeral Contact Pressure With Simulated Anterior Labral and Osseous Defects in Cadaveric Shoulders Before and After Soft Tissue Repair

BACKGROUND

Glenoid rim fractures and erosion can result from traumatic and repeated shoulder dislocations, leading to glenoid bone loss. Traditional instability surgery includes Bankart repair to restore soft tissue anatomy, although a recent trend is to address glenoid bone deficiency when appropriate with a bone block procedure.

HYPOTHESIS/PURPOSE

The purpose of this study was to quantify glenohumeral joint contact pressures as a function of anterior labral detachment, progressive anterior glenoid bone loss, and labral repair. The hypothesis was that a critical glenoid defect size exists whereby labral repair alone cannot restore joint contact pressures, therefore favoring bone block augmentation over soft tissue repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen cadaveric shoulders were tested under a 440-N compressive load simulating glenohumeral abduction positions of 30° and 60° in neutral rotation and 60° with 90° of external rotation. Glenohumeral joint contact pressures were recorded with a Tekscan pressure sensor system in these configurations: (1) intact specimen, (2) Bankart lesion, (3) 10% anterior rim bone defect, (4) 10% bone defect with labral repair, (5) 20% bone defect, (6) 20% bone defect with labral repair, (7) 30% bone defect, and (8) 30% bone defect with labral repair. The joint contact pressures were compared at all configurations.

RESULTS

The Bankart lesion and 10%, 20%, and 30% glenoid defects showed significant (P < .05) increases in mean contact pressures over baseline values. Labral repair at 10% bone loss reduced mean contact pressures to below the intact state, and labral repair of 20% defects demonstrated normalized mean contact pressures. However, mean contact pressures remained statistically elevated compared with baseline values after labral repair of 30% glenoid defects.

CONCLUSION

Glenohumeral joint contact pressures were restored to baseline values after labral repair of 10% and 20% anterior glenoid bone defects. Conversely, labral repair at 30% glenoid bone loss did not restore glenohumeral contact mechanics, yielding elevated contact pressures despite repair. Further study is warranted to investigate the stability (resistance to dislocations) of the glenohumeral joint after labral repair and bone block augmentation.

CLINICAL RELEVANCE

A critical glenoid defect size exists in which labral repair alone does not restore normal glenohumeral contact pressures. Surgeons should carefully evaluate glenoid bone loss before selecting a surgical treatment for shoulder instability.

Glenohumeral joint cartilage contact in the healthy adult during scapular plane elevation depression with external humeral rotation

The shoulder (glenohumeral) joint has the greatest range of motion of all human joints; as a result, it is particularly vulnerable to dislocation and injury. The ability to non-invasively quantify in-vivo articular cartilage contact patterns of joints has been and remains a difficult biomechanics problem. As a result, little is known about normal in-vivo glenohumeral joint contact patterns or the consequences that surgery has on altering them. In addition, the effect of quantifying glenohumeral joint contact patterns by means of proximity mapping, both with and without cartilage data, is unknown. Therefore, the objectives of this study are to (1) describe a technique for quantifying in-vivo glenohumeral joint contact patterns during dynamic shoulder motion, (2) quantify normal glenohumeral joint contact patterns in the young healthy adult during scapular plane elevation depression with external humeral rotation, and (3) compare glenohumeral joint contact patterns determined both with and without articular cartilage data. Our results show that the inclusion of articular cartilage data when quantifying in-vivo glenohumeral joint contact patterns has significant effects on the anterior-posterior contact centroid location, the superior-inferior contact centroid range of travel, and the total contact path length. As a result, our technique offers an advantage over glenohumeral joint contact pattern measurement techniques that neglect articular cartilage data. Likewise, this technique may be more sensitive than traditional 6-Degree-of-Freedom (6-DOF) joint kinematics for the assessment of overall glenohumeral joint health. Lastly, for the shoulder motion tested, we found that glenohumeral joint contact was located on the anterior-inferior glenoid surface.