Instrumented measurement of glenohumeral joint laxity: reliability and normative data

Inconsistency in Shoulder Arthrometers for Measuring Glenohumeral Joint Laxity: A Systematic Review

There is no consensus on how to measure shoulder joint laxity and results reported in the literature are not well systematized for the available shoulder arthrometer devices. This systematic review aims to summarize the results of currently available shoulder arthrometers for measuring glenohumeral laxity in individuals with healthy or injured shoulders. Searches were conducted on the PubMed, EMBASE, and Web of Science databases to identify studies that measure glenohumeral laxity with arthrometer-assisted assessment. The mean and standard deviations of the laxity measurement from each study were compared based on the type of population and arthrometer used. Data were organized according to the testing characteristics. A total of 23 studies were included and comprised 1162 shoulders. Populations were divided into 401 healthy individuals, 278 athletes with asymptomatic shoulder, and 134 individuals with symptomatic shoulder. Sensors were the most used method for measuring glenohumeral laxity and stiffness. Most arthrometers applied an external force to the humeral head or superior humerus by a manual-assisted mechanism. Glenohumeral laxity and stiffness were mostly assessed in the sagittal plane. There is substantial heterogeneity in glenohumeral laxity values that is mostly related to the arthrometer used and the testing conditions. This variability can lead to inconsistent results and influence the diagnosis and treatment decision-making.

Ultrasound Assessment of Anterior Humeral Head Translation in Patients With Anterior Shoulder Instability: Correlation With Demographic, Radiographic, and Clinical Data

Background:

Ultrasonography can be used to quantitatively assess anterior humeral head translation (AHHT) at different degrees of shoulder abduction. Risk factors for recurrent shoulder instability have been identified.

Hypothesis:

It was hypothesized that the number of dislocations or glenoid or humeral bone loss would be associated with more AHHT as measured using ultrasound.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 39 patients who underwent surgery for anterior shoulder instability were prospectively studied. Ultrasound assessment of AHHT was performed immediately after general anesthesia was induced. The upper arm was placed at 0°, 45°, and 90° of abduction, and a 40-N anterior force was applied to the proximal third of the arm. The distance from the posterior edge of the glenoid to that of the humeral head was measured at each abduction angle using ultrasound with and without a 40-N anterior force, and the AHHT was calculated. The differences in translation at each shoulder angle were compared. Additionally, the authors investigated the association between AHHT and demographic, radiographic, and clinical data.

Results:

Compared with the AHHT at 0° of abduction (5.29 mm), translation was significantly larger at 45° of abduction (8.90 mm; P < .01) and 90° of abduction (9.46 mm; P < .01). The mean translation was significantly larger in female patients than in male patients at all degrees of abduction (P ≤ .036 for all). There was no correlation between AHHT at any abduction angle and number of dislocations, clinical data, or radiographic data (including bone loss).

Conclusion:

Ultrasound assessment of AHHT showed larger amounts of laxity at 45° and 90° than at 0° of abduction. Anterior glenohumeral laxity was greater in female than male patients. Glenoid or humeral bone loss did not correlate with AHHT, thereby clarifying that bone loss has no direct effect on measurements of capsular laxity in neutral rotation.

Objective measurement of Inferior-Directed stiffness in glenohumeral joint using a specially designed robotic device in healthy shoulders; Within- and Between-Session reliability

Clinical assessment of capsuloligamentous structures of the glenohumeral joint has been qualitative and subjective in nature, as demonstrated by limited intra- and inter-rater reliability. Robotic devices were utilized to develop a clinically objective measurement technique for glenohumeral joint stiffness. The purpose of this study was to quantify the amount of inferior-direction stiffness of the glenohumeral joint using a safe clinical device in the asymptomatic individuals, and to determine between trial and between session reliability of the robotic device. Twenty healthy subjects were recruited via convenience sampling. Inferior-directed translation and applying force were measured using displacement and force sensors of a robotic device. The stiffness values were calculated as the mean of the slopes of the linear portions of the force-displacement curves for the cycles obtained after familiarization and preconditioning. Four trials for each measurement occasion were averaged to determine the stiffness value for each subject in one session. Repeatability of glenohumeral joint stiffness measurements for between trials and between two sessions was determined using intraclass correlation values and standard error of the measurements. The mean stiffness value was 1.50 N/mm (±0.40) and 1.52 N/mm (±0.40), respectively. The robotic device for stiffness assessment was reliable for repeated measures of stiffness in one session, and between sessions with ICC equal 0.96 (95% CI 0.93-0.98), and 0.97 (95% CI 0.95-0.99), respectively. The SEM between the trials was in each session 0.08 N/mm. The results of this study provide that our robotic technique for quantifying glenohumeral joint stiffness is precise and reproducible.

Pitching shoulder passive flexibility: torque-angle analysis for external rotation and internal rotation

In this study, a custom device was developed to analyse the pitching shoulder's external rotation (ER) and internal rotation (IR) passive flexibility. We analysed three novel measures: the resistance onset angle (ROA = angle where the shoulder begins stretching), rotational stiffness, and torque at the end range of motion (ROM). The purpose was to conduct a bilateral analysis to determine if there are significant differences between the throwing and non-throwing shoulder. Participants were 30 upper level pitchers (13 division I, 17 minor league). During testing, pitchers laid supine on a treatment table and the arm was secured to a rotational wheel with the shoulder abducted 90° and elbow flexed 90°. Dependent t-tests revealed significant (p < 0.01) and relatively extreme bilateral differences for all three variables. The throwing shoulder had: increased ER ROA (9°), decreased IR ROA (5.3°), increased ER stiffness (17%), increased IR stiffness (34%), increased ER torque (21%), and increased IR torque (30%). Secondary correlation analysis was completed to determine if the torque-angle variables were good predictors of the end ROM. Stiffness correlations were weak for ER (r = 0.35, p = 0.048) and IR (r = 0.42, p = 0.017) but ROA correlations were strong for ER (r = 0.85, p < 0.001) and IR (r = 0.86, p < 0.001).

Developing reliable measures of the passive torque-angle relationship for shoulder internal and external rotation: Implications for overhead athletics

OBJECTIVES

1) Thoroughly assess shoulder flexibility by establishing the passive torque-angle relationship for internal and external rotation with the arm in an overhead athletics position (abducted 90°) and 2) test the reliability of four passive torque-angle measures.

DESIGN

Reliability study.

SETTING

Data were collected in a university biomechanics laboratory.

PARTICIPANTS

Bilateral shoulder flexibility of 15 male college students (20.7 ± 1.1 y) was evaluated twice in two sessions over 7-10 days.

MAIN OUTCOME MEASURES

For both ER and IR, reliability was assessed bilaterally (intra-session, inter-session, and inter-tester) for the traditional range of motion measure and three novel kinetic measures: torque at end ROM, resistance onset angle, rotational stiffness. This resulted in 48 total assessments.

RESULTS

Thirty-four assessments had good to excellent reliability (ICC ≥ 0.8), 10 had fair reliability (0.7 ≤ ICC < 0.8), and 4 had poor reliability (ICC< 0.7). Three of the four flexibility measures had a good overall ICC score: ROM (0.83), torque at end ROM (0.84), and resistance onset angle (0.81). The fourth, stiffness, had a fair overall reliability score (0.74).

CONCLUSIONS

The passive torque-angle measures should be assimilated into clinical and research settings to determine the relevance to injury, rehabilitation, and performance.

Physical Exam and Evaluation of the Unstable Shoulder

Background:

The clinical evaluation of the patient with shoulder instability can be challenging. The pathological spectrum ranges from the straightforward “recurrent anterior dislocation” patient to the overhead athlete with a painful shoulder but not clear instability episodes. Advances in shoulder arthroscopy and imaging have helped in understanding the anatomy and physiopathology of the symptoms. The aim of this general article is to summarize the main examination manoeuvres that could be included in an overall approach to a patient with a suspicion of instability.

Material and Methods:

In order to achieve the above-mentioned objective, a thorough review of the literature has been performed. Data regarding sensibility and specificity of each test have been included as well as a detailed description of the indications to perform them. Also, the most frequent and recent variations of these diagnostic tests are included.

Results:

Laxity and instability should be considered separately. For anterior instability, a combination of apprehension, relocation and release tests provide great specificity. On the other hand, multidirectional or posterior instability can be difficult to diagnose especially when the main complain is pain.

Conclusion:

A detailed interview and clinical examination of the patient are mandatory in order to identify a shoulder instability problem. Range of motion of both shoulders, clicking of catching sensations as well as pain, should be considered together with dislocation and subluxation episodes. Specific instability and hyperlaxity tests should be also performed to obtain an accurate diagnosis.

Stress radiography for clinical evaluation of anterior shoulder instability

BACKGROUND

The purpose of this study was to examine the validity of stress radiography using the Telos GA-IIE as a clinical methodology to evaluate shoulder instability.

METHODS

On 36 anterior shoulder dislocators and 23 uninjured volunteers, 4 types of stress radiographs were captured while applying 15 daN of force anteriorly (AER0 and AER60) and posteriorly (PER0 and PER60) at 2 different positions: (1) 90° of abduction combined with 0° external rotation and (2) 90° of abduction combined with 60° external rotation. The results of the anterior drawer test and of the same test under anesthesia were correlated.

RESULTS

AER0 and AER60 from the affected shoulder revealed significantly larger displacement than on the normal side (P < .05), and all 4 radiographs from the affected joints demonstrated significantly larger displacement (P < .05) than in the volunteers. Among the 4 types of radiographs, AER0 and AER60 showed significantly higher displacement in the patients (P < .001), whereas there were no differences in the volunteers (P = .167). The results of the anterior drawer test positively correlated to AER60 (Pearson correlation coefficient [PCC] = 0.453; P = .005) and AER0 (PCC = 0.529; P = .001), and those of examination under anesthesia weakly correlated to AER60 (PCC = 0.287; P = .264) but highly correlated to AER0 (PCC = 0.695; P = .002).

CONCLUSION

Stress radiographs on the affected shoulder frequently correlated with physical examinations, and the displacement of >3 mm on AER0 suggests anterior instability.

In vivo measurements of humeral movement during posterior glenohumeral mobilizations

OBJECTIVES

The purpose of this study was to quantify in vivo posterior translational movements occurring in the glenohumeral joint during posterior mobilizations and to determine the intratester reliability of those posterior translational movements.

METHODS

Twenty-eight individuals (17 females, 11 males) participated in this study. One physical therapist utilized a Kaltenborn approach to apply three grades of posterior humeral mobilization. A hand held dynamometer was used to quantify the force used during each grade of mobilization. Ultrasound imaging was used to visualize and measure posterior humeral movement. Statistical analysis included descriptive statistics for force and posterior movement, intraclass correlation coefficient (ICC) for intrarater reliability of force and posterior movement during each grade of mobilization and paired t-tests to compare movement and force between grades of mobilization.

RESULTS

Mean posterior movement (mm) measurements were 3.0, 8.2 and 10.7 for grade I, grade II and grade III mobilizations, respectively. Mean force (Newtons) measurements used during mobilization were 41.7, 121.5 and 209.4 for grade I, grade II and grade III mobilizations, respectively. The ICCs ranged from 0.849 to 0.905 for movement and from 0.717 to 0.889 for force. Force and measurement values were significantly different between grades of mobilization and between dominant and non-dominant arms. Gender was found to be significantly associated with force.

DISCUSSION

Mean movements and mean forces occurring during posterior mobilization increased with increasing grades. Intratester reliability was high for all grades of manual mobilization supporting the use of subjective feedback to determine appropriate force application. Quantification of forces and movements helps to clarify parameters that can serve as a reference for clinical practice.

Physical examination of the shoulder

This article summarizes the overall assessment of the shoulder joint and seeks to help direct clinicians to diagnose shoulder pathology using standard and specific physical examinations. The history and standard examination can prompt the examiner to focus on specific tests to further evaluate the shoulder and limit the differential diagnoses. An appropriate and directed shoulder physical examination allows the clinician to focus on further diagnostic strategies and treatment options for the patient.

Effects of external rotation on anteroposterior translations in the shoulder: a pilot study

BACKGROUND

Using physical examination to make the diagnosis of shoulder instability can be difficult, because typical examination maneuvers are qualitative, difficult to standardize, and not reproducible. Measuring shoulder translation is especially difficult, which is a particular problem, because measuring it inaccurately may result in improper treatment of instability.

QUESTIONS/PURPOSES

The objective of this study was to use a magnetic motion tracking system to quantify the effects of external rotation of the abducted shoulder on a simulated simple translation test in healthy subjects. Specifically, we hypothesized that (1) increasing external rotation of the abducted shoulder would result in decreasing translation; (2) intraobserver repeatability would be less than 2 mm at all external rotation positions; and (3) mean side-to-side differences would be less than 2 mm at all external rotation positions.

METHODS

The intraobserver repeatability and side-to-side differences of AP translation were quantified with a noninvasive magnetic motion tracking system and automated data analysis routine in nine healthy subjects at four positions of external rotation with the arm abducted. A shoulder positioning apparatus was used to maintain the desired arm position.

RESULTS

No differences in translations between the positions of external rotation were found (p = 0.48). Intraobserver repeatability was 1.1 mm (SD, 0.8 mm) and mean side-to-side differences were small: 2.7 mm (SD, 2.8 mm), 2.8 mm (SD, 1.8 mm), 2.5 mm (SD, 1.8 mm), and 4.0 mm (SD, 2.6 mm) at 0°, 20°, 40°, and 60° of external rotation, respectively.

CONCLUSIONS

The intraobserver repeatability was strong and the side-to-side differences in translation were small with the magnetic motion tracking system, which is encouraging for development of an improved quantitative test to assess shoulder translation for fast and low-cost diagnosis of shoulder instability.

CLINICAL RELEVANCE

Clinicians may not have to position the contralateral, normal, abducted shoulder in precisely the same position of external rotation as the injured shoulder while performing side-to-side comparisons.

Shoulder instability in professional rugby players-the significance of shoulder laxity

OBJECTIVE

Shoulder instability is a common cause of morbidity among professional rugby union players. This study explores whether the risk of shoulder dislocation is associated with innate shoulder laxity.

DESIGN

Retrospective cohort study.

SETTING

Clinical sports medicine research at professional rugby clubs.

PARTICIPANTS

One hundred sixty-nine healthy rugby players (mean age 25.1 years) with no history of instability in either shoulder and 46 players (mean age 27.5 years) with shoulder instability in one shoulder (patient group).

MAIN OUTCOME MEASURES

Anterior, inferior, and posterior laxity was measured in both shoulders for healthy players and in the uninjured shoulder only for injured players using dynamic ultrasound.

RESULTS

There was no significant difference between the nondominant (anterior: mean 2.9 ± 1.2 mm; inferior: mean 3.1 ± 1.0 mm; posterior: mean 5.1 ± 1.7 mm) and dominant (anterior: mean 3.1 ± 1.1 mm; inferior: mean 2.9 ± 1.0 mm; posterior: mean 4.9 ± 1.7 mm) shoulders in healthy players (P > 0.05). The comparison between healthy shoulders (anterior: mean 3.0 ± 1.2 mm; inferior: mean 3.0 ± 1.0 mm; posterior: mean 5.0 ± 1.7 mm) and the uninjured shoulder (anterior: mean 4.2 ± 1.7 mm; inferior: mean 3.4 ± 1.2 mm; posterior: mean 6.2 ± 3.0 mm) from injured players identified that players with unstable shoulders have a significantly higher shoulder translation in their uninjured shoulder than healthy players (P < 0.05).

CONCLUSIONS

Formal assessment of shoulder translation using dynamic ultrasound should enable sports medicine practitioners to identify players at greatest risk of subsequent shoulder instability for targeted prehabilitation programs.

Objective evaluation of shoulder function using body-fixed sensors: a new way to detect early treatment failures?

BACKGROUND

Variable definitions of outcome (Constant score, Simple Shoulder Test [SST]) have been used to assess outcome after shoulder treatment, although none has been accepted as the universal standard. Physicians lack an objective method to reliably assess the activity of their patients in dynamic conditions. Our purpose was to clinically validate the shoulder kinematic scores given by a portable movement analysis device, using the activities of daily living described in the SST as a reference. The secondary objective was to determine whether this device could be used to document the effectiveness of shoulder treatments (for glenohumeral osteoarthritis and rotator cuff disease) and detect early failures.

METHODS

A clinical trial including 34 patients and a control group of 31 subjects over an observation period of 1 year was set up. Evaluations were made at baseline and 3, 6, and 12 months after surgery by 2 independent observers. Miniature sensors (3-dimensional gyroscopes and accelerometers) allowed kinematic scores to be computed. They were compared with the regular outcome scores: SST; Disabilities of the Arm, Shoulder and Hand; American Shoulder and Elbow Surgeons; and Constant.

RESULTS

Good to excellent correlations (0.61-0.80) were found between kinematics and clinical scores. Significant differences were found at each follow-up in comparison with the baseline status for all the kinematic scores (P < .015). The kinematic scores were able to point out abnormal patient outcomes at the first postoperative follow-up.

CONCLUSION

Kinematic scores add information to the regular outcome tools. They offer an effective way to measure the functional performance of patients with shoulder pathology and have the potential to detect early treatment failures.

Electrocautery of the patellar rim in primary total knee replacement: beneficial or unnecessary?

The management of the patella during total knee replacement is controversial. In some studies the absence of patellar resurfacing results in residual anterior knee pain in over 10% of patients. One form of treatment which may be used in an endeavour to reduce this is circumferential patellar rim electrocautery. This is believed to partially denervate the patella. However, there is no evidence of the efficacy of this procedure, nor do we know if it results in harm.

A retrospective comparative cohort study was performed of 192 patients who had undergone a primary total knee replacement with the porous coated Low Contact Stress rotating platform prosthesis without patellar resurfacing between 2003 and 2007. In 98 patients circumferential electrocautery of the patellar rim was performed and in 94 patients it was not. The two groups were matched for gender and age. The general Oxford Knee Score and the more specific patellar score for anterior knee pain were used to assess patient outcomes a minimum of two years post-operatively.

No statistically significant differences were noted between the groups for either scoring system (p = 0.41 and p = 0.87, respectively). Electrocautery of the patella rim did not improve the outcome scores after primary total knee replacement in our patients.

Stiffness regulation and muscle-recruitment strategies of the shoulder in response to external rotation perturbations

BACKGROUND

The complex interactions between capsuloligamentous structures and muscle-recruitment strategies that maintain glenohumeral stability remain unclear. The purposes of the present study were to determine whether stiffness regulation and muscle-activation strategies differed under varying joint positions and levels of contraction in the shoulder and to determine the relationship between generalized joint laxity, glenohumeral joint laxity, and joint stiffness.

METHODS

Forty healthy, physically active subjects with a mean age (and standard deviation) of 25.2 +/- 4.6 years, a mean height of 174.7 +/- 6.7 cm, and a mean mass of 73.1 +/- 13.8 kg were tested. Shoulder stiffness and the activation of muscles (including the rotator cuff and the anterior deltoid) were measured at two levels of internal rotation torque (0% and 50% of maximum) and two joint positions (0 degrees and 90% of maximum external rotation) before and after a 5 degrees external rotation perturbation. Generalized laxity and glenohumeral joint laxity (in the anterior, posterior, and inferior directions) were also assessed.

RESULTS

Stiffness was 77% greater at 50% of maximum internal rotation torque than at 0% of maximum internal rotation torque (p < 0.001) but was not significantly different between joint positions (p = 0.73). From 0% to 50% of maximum internal rotation torque, preparatory and reactive recruitment of the subscapularis increased significantly more (p < 0.05) than those of the other muscles. Also, subscapularis preparatory activity was 36% greater in 0 degrees of external rotation than in 90% of maximum external rotation (p < 0.01). Generalized joint laxity (as indicated by a score of >/=4) was present in 20% of the subjects. Glenohumeral joint laxity (as indicated by a grade of >/=2) was present in the anterior, posterior, and inferior directions in 13%, 15%, and 15% of the subjects, respectively. No correlation existed between passive stiffness and generalized or glenohumeral laxity (r = -0.12 to 0.29; p = 0.08 to 0.48).

CONCLUSIONS

Moderate levels of muscle contraction can significantly increase glenohumeral joint stiffness and stability. Preactivation of the subscapularis appears to be the primary dynamic stabilizer with the arm in 0 degrees of external rotation. However, with the arm in 90% of maximum external rotation (the apprehension position), less subscapularis activity is observed and the maintenance of stability may shift toward other musculoskeletal structures because joint stiffness does not change. A relationship between generalized joint laxity, glenohumeral laxity, and stiffness was not observed in healthy subjects.

Laxity testing of the shoulder: a review

Laxity testing is an important part of the examination of any joint. In the shoulder, it presents unique challenges because of the complexity of the interactions of the glenohumeral and scapulothoracic joints. Many practitioners believe that laxity testing of the shoulder is difficult, and they are unclear about its role in evaluation of patients. The objectives of the various laxity and instability tests differ, but the clinical signs of such tests can provide helpful information about joint stability. This article summarizes the principles of shoulder laxity testing, reviews techniques for measuring shoulder laxity, and evaluates the clinical usefulness of the shoulder laxity tests. Shoulder laxity evaluation can be a valuable element of the shoulder examination in patients with shoulder pain and instability.

Simulated humeral avulsion of the glenohumeral ligaments: a new instability model

Humeral avulsion of the glenohumeral ligaments (HAGL) is an infrequent cause of shoulder instability. Experimental studies on this lesion are rare. This study was undertaken to determine the extent of humeral-based capsuloligamentous damage required for dislocation to occur. In 65 fresh cadaver shoulders, a humeral-sided ligamentous cutting sequence was done. After each step, degree of sulcus, translation, and instability were evaluated with an electromagnetic tracking device. There was a high degree of correlation between the amount of cut done and the resulting degree of instability. The order of the ligamentous cuts had no significant influence. For a dislocation to occur at least 3 zones had to be cut. Simulated HAGL can be used as a model for shoulder instability, although further experiments are needed to validate this model fully. Extensive capsuloligamentous lesions on the humeral side seem to be required before dislocation can occur. This may be a factor explaining the relative paucity of HAGL in clinical series.

The effect of isolated labrum resection on shoulder stability

The present study was initiated to determine whether glenohumeral instability and dislocation can result from isolated lesions of the glenoid labrum in an arthroscopic cadaver model. Adjacent combinations of four zones of the labrum (superior, anterosuperior, anteroinferior and inferior) were sequentially removed with a motorised shaver, taking great care to leave the capsule intact in 24 cadaver shoulders. Stability was tested before and after inserting the scope and after each resection step. Inferior stability was examined by performing an inferior drawer test. Anterior stability was evaluated with an anteroposterior drawer test in 0 degrees of abduction and with a load-and-shift test in external rotation and 90 degrees abduction. Labral resection of all four zones maximally resulted in a grade 1 inferior instability (<10 mm inferior translation). When two adjacent labral zones were resected, a grade 2 anterior drawer (>10 mm anterior but no medial translation) was seen in 17% of the specimens. This was seen in one more specimen after the addition of a third zone. There were no differences in the stability of the load-and-shift test after any amount of labral resection. Total labral debridement increased inferior and anterior translation, but did not allow the humeral head to dislocate. The degree of stability in the cocked-arm position, which is the most prone to dislocation, is not altered. In patients, isolated labral tears, that is, without evidence of capsuloligamentous damage, can probably be safely debrided without risking glenohumeral instability to the point of dislocation. Nevertheless, anterior translation may significantly increase when two or more zones are resected.

Sonographic stress measurement of glenohumeral joint laxity in collegiate swimmers and age-matched controls

BACKGROUND

Glenohumeral laxity that is greater than normal has been implicated as a causal factor in the development of shoulder pain and dysfunction in elite swimmers; however, quantitative evidence demonstrating greater-than-normal glenohumeral joint laxity in swimmers is lacking.

OBJECTIVE

To quantify glenohumeral joint laxity in elite swimmers and nonswimming controls using stress sonography.

STUDY DESIGN

Controlled laboratory study.

METHODS

Force-displacement measures were performed bilaterally in 42 National Collegiate Athletic Association Division I swimmers and 44 age-matched controls. Of the 42 swimmers, 27 (64%) reported a history of unilateral or bilateral shoulder pain resulting from swimming. Ultrasound imaging was used to measure glenohumeral joint displacement under stressed and non-stressed conditions.

RESULTS

An analysis of variance revealed no significant difference in glenohumeral joint displacement between swimmers (anterior, 2.82 +/- 1.7 mm; posterior, 5.30 +/- 2.4 mm) and age-matched controls (anterior, 2.74 +/- 1.7 mm; posterior, 4.90 +/- 2.7 mm). No significant difference in glenohumeral joint displacement was found between swimmers with a history of shoulder pain (anterior, 2.90 +/- 1.6 mm; posterior, 5.42 +/- 2.3 mm) versus swimmers without a history of shoulder pain (anterior, 2.74 +/- 1.8 mm; posterior, 5.14 +/- 2.6 mm). Shoulders displayed significantly more glenohumeral joint displacement in the posterior direction compared to the anterior direction (P < .001).

CONCLUSIONS

Our instrumented technique was unable to identify significantly greater glenohumeral joint displacement in elite swimmers compared to nonswimming controls, and elite swimmers with a history of shoulder pain were not found to have significantly more glenohumeral joint displacement compared to swimmers without a history of shoulder pain.

CLINICAL RELEVANCE

Objective assessment of glenohumeral joint displacement in athletes participating in overhead-motion sports may be important for injury prevention and management.

Evaluation of general joint laxity, shoulder laxity and mobility in competitive swimmers during growth and in normal controls

The aim of the study was to evaluate differences between competitive swimmers and a reference group of school children concerning general joint laxity, laxity of the glenohumeral joint and range of motion in the shoulder. Materials and methods. Competitive swimmers (n = 120) were compared with references consisting of age and gender matched school children (n = 1277). General joint laxity was evaluated with the Beighton score. Anterior glenohumeral laxity was assessed according to the drawer test, and inferior glenohumeral laxity according to the sulcus test. Shoulder rotation was measured with a goniometer.

RESULTS

Male swimmers of both age groups showed a higher degree of general joint laxity compared with the reference group while 9-year-old female swimmers alone had a lower degree of general joint laxity compared with references. No significant difference concerning shoulder laxity was noticed between groups. There was a decreased internal rotation in male and female swimmers as compared with the reference group. External rotation was reduced in female swimmers as compared with the female references. The same result was observed in male swimmers, but only at the age of 12 years.

CLINICAL CONSEQUENCE

Competitive swimming in children seems to lead to a decreased range of motion with regard to shoulder rotation. However, the reason for this is still unclear and further investigations are needed.

Comparison of dynamic sonography to stress radiography for assessing glenohumeral laxity in asymptomatic shoulders

BACKGROUND

Stress radiography has been the established imaging method for quantifying glenohumeral joint laxity. Dynamic ultrasound is an alternative imaging method that may be used to measure glenohumeral laxity; however, validity and repeatability have not been examined.

OBJECTIVE

To determine criterion-related validity and repeatability of a sonographic imaging method for measuring glenohumeral laxity in asymptomatic shoulders.

STUDY DESIGN

Controlled laboratory study.

METHODS

In experiment 1, 20 subjects were assessed for glenohumeral laxity using stress radiography and dynamic ultrasound. In the second experiment, 13 subjects were assessed for laxity in 2 separate test sessions using the dynamic ultrasound technique.

RESULTS

Correlational analysis between the sonographic and radiographic measures revealed an r = 0.79 (r(2) = 0.62), indicating excellent criterion-related validity for the sonographic imaging method. Test-retest repeatability was 0.72 and 0.85 for anterior and posterior translation, respectively, and interrater repeatability was 0.96 and 0.99 for anterior and posterior translation, respectively.

CONCLUSIONS

Dynamic ultrasound appears to be a valid and repeatable method for assessing glenohumeral laxity in a clinical setting.

CLINICAL RELEVANCE

Based on the results of this study, dynamic ultrasound is a repeatable and valid method for measuring glenohumeral laxity and therefore may be used as a viable replacement for stress radiography during assessments of glenohumeral laxity.

Reliability of Intratester and Intertester Measurements Derived from an Instrumented Ankle Arthrometer

Context:

Measurement reliability is critical when new sports-medicine devices or techniques are developed.

Objective:

To determine the reliability of laxity measurements obtained from an instrumented ankle arthrometer.

Design:

Intratester reliability was examined using a test–retest design, and intertester reliability was assessed using the measurements recorded by 2 different examiners on a separate group of participants.

Setting:

Sports-medicine research laboratory.

Participants:

40 participants with no history of ankle injury, equally divided across the 2 studies.

Measurements:

Laxity measurements included anteroposterior (AP) displacement during loading to 125 N. Inversion–eversion (I–E) rotation was tested during loading to 4000 N-mm. The measures were analyzed using intraclass correlation coefficients (ICCs) and dependentttests.

Results:

Good to excellent ICCs (.80–.99) for intratester and intertester reliability. A significant difference in measures was observed between testers for both AP displacement and I–E rotation.

Conclusions:

Laxity measurements from an instrumented ankle arthrometer are reliable across test days and examiners

In vivo quantification of capsular end-point in the nonimpaired glenohumeral joint using an instrumented measurement system

STUDY DESIGN

Single-group factorial.

OBJECTIVES

Quantify glenohumeral joint translations as a function of force using an instrumented measurement system. Our first specific aim was to compare the magnitude of force (N) required to reach capsular end-point between the anterior, posterior, and inferior directions. Our second specific aim was to compare the magnitude of translation (mm) at capsular end-point between the anterior, posterior, and inferior directions.

BACKGROUND

Manual force-displacement techniques are subjective in nature, and the clinician must rely on "feel" to determine capsular end-point. Several investigators have attempted to utilize more objective measures at the glenohumeral joint, however none have quantified the force or displacements necessary to achieve a true capsular end-point.

METHODS AND MEASURES

An arthrometric technique was used to measure anterior, posterior, and inferior glenohumeral translations in 20 nonimpaired shoulders (11 women and 9 men with a mean age of 20.9 +/- 3.6 years).

RESULTS

The magnitude of applied force required to reach capsular end-point was significantly different between directions of translations. Anterior-directed translations required a significantly greater magnitude of applied force to reach capsular end-point than inferior-directed translations. The magnitude of translation was not significantly different between directions at capsular end-point.

CONCLUSIONS

Applied forces in the range of 181 to 203 N are necessary to reach capsular end-point in subjects with nonimpaired shoulders. Anterior translation required significantly higher forces (203.1 +/- 13.1 N) to reach capsular end-point than inferior translation (181.4 +/- 31.9 N).

Instrumented measurement of glenohumeral joint laxity and its relationship to passive range of motion and generalized joint laxity

The purpose of this study was to objectively characterize in vivo glenohumeral joint laxity using an instrumented shoulder arthrometer. Secondary objectives were to examine the relationship of glenohumeral joint laxity with passive range of motion and generalized joint laxity. Fifty-one recreational athletes with no history of shoulder injury or long-term participation in overhead sports participated in this study. Anterior and posterior laxity data were obtained at displacement forces of 67, 89, 111, and 134 N. Bilateral passive shoulder range of motion measures were obtained, and a modified Beighton Mobility Score was used to quantify generalized joint laxity. There were no significant differences in glenohumeral joint laxity between the right and left shoulders (P values = 0.14 to 0.73). No significant differences in laxity were seen between directions (F(1,400) = 1.35, P = 0.25). However, significant differences were observed between force levels (F(3,400) = 27.17, P < 0.0001). No moderate or stronger correlations between laxity, passive range of motion, and generalized joint laxity were seen. These data confirm the presence of a wide spectrum of symmetric laxity in subjects that fails to correlate strongly with passive range of motion or generalized joint laxity.