Three-Dimensional Magnetic Resonance Imaging of Glenohumeral Dysplasia in Neonatal Brachial Plexus Palsy

Glenohumeral abduction contractures after residual neonatal brachial plexus injury

Glenohumeral abduction contractures are common in patients with neonatal brachial plexus injury, but little has been previously published about them. We conducted a retrospective analysis of data prospectively collected from 205 consecutive children (108 female) of mean age 9.6 years with neonatal brachial plexus injury (C5-C6, 58%; C5-C7, 29%; C5-T1, 14%). Most children (69%) showed a glenohumeral abduction contracture, it being more common in those with upper neonatal brachial plexus injury.Level of evidence: III.

Influence of Brachial Plexus Birth Injury Location on Glenohumeral Joint Morphology

PURPOSE

Patient presentation after brachial plexus birth injury (BPBI) is influenced by nerve injury location; more contracture and bone deformity occur at the shoulder in postganglionic injuries. Although bone deformity after postganglionic injury is well-characterized, the extent of glenohumeral deformity after preganglionic BPBI is unclear.

METHODS

Twenty Sprague-Dawley rat pups received preganglionic or postganglionic neurectomy on a single forelimb at postnatal days 3 to 4. Glenohumeral joints on affected and unaffected sides were analyzed using micro-computed tomography scans after death at 8 weeks after birth. Glenoid version, glenoid inclination, glenoid and humeral head radius of curvature, and humeral head thickness and width were measured bilaterally.

RESULTS

The glenoid was significantly more declined in affected compared with unaffected shoulders after postganglionic (-17.7° ± 16.9°) but not preganglionic injury. Compared with the preganglionic group, the affected shoulder in the postganglionic group exhibited significantly greater declination and increased glenoid radius of curvature. In contrast, the humeral head was only affected after preganglionic but not postganglionic injury, with a significantly smaller humeral head radius of curvature (-0.2 ± 0.2 mm), thickness (-0.2 ± 0.3 mm), and width (-0.3 ± 0.4 mm) on the affected side compared with the unaffected side; changes in these metrics were significantly associated with each other.

CONCLUSIONS

These findings suggest that glenoid deformities occur after postganglionic BPBI but not after preganglionic BPBI, whereas the humeral head is smaller after preganglionic injury, possibly suggesting an overall decreased biological growth rate in this group.

CLINICAL RELEVANCE

This study expands understanding of the altered glenoid and humeral head morphologies after preganglionic BPBI and its comparisons with morphologies after postganglionic BPBI.

Neonatal brachial plexus injuries and their impact on growing bone. An experimental study

Neonatal brachial plexus palsy remains a problem, even in light of current advances in perinatal care. While many cases resolve spontaneously, the concern remains on the best means of surgical management for restoration of elbow flexion and shoulder reanimation. The present experimental study in an animal model examines the evidence that supports that neonatal brachial plexus injuries result in structural changes in the affected bone. The study suggests that if the microsurgical reinnervation takes place early enough, these changes may be diminished. On the other hand there is no way to identify at birth, which injuries will be permanent and will need surgical repair and which will spontaneously improve.

Team Approach: Management of Brachial Plexus Birth Injury

Brachial plexus birth injury is an upper-extremity paralysis that occurs from a traction injury to the brachial plexus during birth. Approximately 10% to 30% of children with a brachial plexus birth injury have residual neurologic deficits with associated impact on upper-limb function. Management of brachial plexus birth injuries with a multidisciplinary team allows optimization of functional recovery while avoiding unnecessary intervention. Early occupational therapy should be initiated with a focus on range of motion and motor learning. The need for microsurgical reconstruction of the brachial plexus can be predicted based on early physical examination findings, and reconstruction is generally performed at 3 to 9 months of age. The majority of children with residual neurologic deficits develop associated glenohumeral dysplasia. These children may require secondary procedures, including botulinum toxin injection, subscapularis and pectoralis lengthening, shoulder capsular release, shoulder tendon transfer, and humeral osteotomy.

Integrated iterative musculoskeletal modeling predicts bone morphology following brachial plexus birth injury (BPBI)

Brachial plexus birth injury (BPBI) is the most common nerve injury among children. The glenohumeral joint of affected children can undergo severe osseous deformation and altered muscle properties, depending on location of the injury relative to the dorsal root ganglion (preganglionic or postganglionic). Preganglionic injury results in lower muscle mass and shorter optimal muscle length compared to postganglionic injury. We investigated whether these changes to muscle properties over time following BPBI provide a mechanically-driven explanation for observed differences in bone deformity between preganglionic and postganglionic BPBI. We developed a computational framework integrating musculoskeletal modeling to represent muscle changes over time and finite element modeling to simulate bone growth in response to mechanical and biological stimuli. The simulations predicted that the net glenohumeral joint loads in the postganglionic injury case were nearly 10.5% greater than in preganglionic. Predicted bone deformations were more severe in the postganglionic case, with the glenoid more declined (pre: -43.8°, post: -51.0°), flatter with higher radius of curvature (pre: 3.0 mm, post: 3.7 mm), and anteverted (pre: 2.53°, post: 4.93°) than in the preganglionic case. These simulated glenoid deformations were consistent with previous experimental studies. Thus, we concluded that the differences in muscle mass and length between the preganglionic and postganglionic injuries are critical mechanical drivers of the altered glenohumeral joint shape.

Preoperative multislice computed tomography evaluation of shoulder deformities in brachial plexus birth palsy patients undergoing tendon transfer

BACKGROUND

Brachial plexus birth palsy (BPBP) refers to a birth related paralysis of the upper extremity. The current study was designed to evaluate the efficacy of computed tomography (CT) in the assessment of humeral head posterior subluxation and glenoid retroversion preoperatively and to evaluate whether or not bony deformity correlates with functional improvement (based on Modified Mallet Score) following tendon transfer in brachial plexus birth palsy patients.

PATIENTS AND METHODS

This prospective study included 30 patients, 15 below 4 years and 15 above 4 years old, with a mean age 3.65 ± 1.39 (range 2-8) years old. Thirteen patients were males (43.3%) and 17 were females (56.6%). The left side was affected in 13 patients (43.3%), while the right in 17 (56.7%). The Modified Mallet Score was used for clinical assessment of the shoulder function. A multislice CT scan with 3D reconstruction was used as a preoperative radiological assessment of the shoulder. An electromyography (EMG) of the muscles around the shoulder was performed. All patients were operated upon by anterior release of the internal rotators to improve the external rotation range of motion and by transfer of teres major and latissimus dorsi to improve the abduction motion through one anterior deltopectoral incision and a small posterosuperior incision. Postoperatively, the range of shoulder abduction and external rotation had been assessed after shoulder spica removal and till the end of follow up.

RESULTS

Fourteen patients (46.7%) had a normal glenoid version angle (normal range from -12° to 2°) and normal range of articulation with the glenoid (42.3%-71.4%) and 16 patients (53.3%) had an abnormal glenoid version angle and abnormal range of articulation with the glenoid. According to the Modified Mallet Score, there was a statistically significant difference in the mean value of global abduction (P = 0.04), external rotation (P = 0.03), hand to mouth (P = 0.02), hand to neck (P = 0.03) and hand to spine (P = 0.02) between the pre- and post-operative assessment of all patients. There was a statistically significant difference in the mean value of postoperative Modified Mallet Score between the patients under the age of 4 years and those above the age of 4 years. There was no statistically significant difference between the patients with normal CT angles and those with abnormal CT angles. There was no statistically significant difference in the mean value of glenoid version angle and percentage of humeral head articulation between the patients below the age of 4 years and those above 4 years (P = 0.845).

CONCLUSION

The study concluded that the glenoid version angle and humeral head articulation percentage do not negatively affect results of the tendon transfer around the shoulder in patients of upper brachial plexus birth palsy.

LEVEL OF EVIDENCE

IV.

Computational analysis of glenohumeral joint growth and morphology following a brachial plexus birth injury

Children affected with brachial plexus birth injury (BPBI) undergo muscle paralysis. About 33% of affected children experience permanent osseous deformities of the glenohumeral joint. Recent evidence suggests that some cases experience restricted muscle longitudinal growth in addition to paralysis and reduced range of motion at the shoulder and elbow. It is unknown whether altered loading due to paralysis, muscle growth restriction and contracture, or static loading due to disuse is the primary driver of joint deformity after BPBI. This study uses a computational framework integrating finite element analysis and musculoskeletal modeling to examine the mechanical factors contributing to changes in bone growth and morphometry following BPBI. Simulations of 8 weeks of glenohumeral growth in a rat model of BPBI predicted that static loading of the joint is primarily responsible for joint deformation consistent with experimental measures of bone morphology, whereas dynamic loads resulted in normal bone growth. Under dynamic loading, glenoid version angle (GVA), glenoid inclination angle (GIA), and glenoid radius of curvature (GRC) (-1.3°, 38.2°, 2.5 mm respectively) were similar to the baseline values (-1.8°, -38°, 2.1 mm respectively). In the static case with unrestricted muscle growth, these measures increased in magnitude (5.2°, -48°, 3.5 mm respectively). More severe joint deformations were observed in GIA and GRC when muscle growth was restricted (GVA: 3.6°, GIA: -55°, GRC: 4.0 mm). Predicted morphology was consistent with literature reports of in vivo glenoid morphology following postganglionic BPBI. This growth model provides a framework for understanding the most influential mechanical factors driving glenohumeral deformity following BPBI.

Three-dimensional MRI analyses of prereduced femoral head sphericity in patients with developmental dysplasia of the hip after Pavlik harness failure

We used three-dimensional (3D) MRI to assess the sphericity of the cartilaginous femoral head in developmental dysplasia of the hip. We assessed 21 children using 3D-MRI. The smallest sphere including the femoral head cartilage was drawn, the diameter was measured, and the center of the sphere was defined. We compared the diameters of the femoral heads between unaffected and diseased sides. The diameter of the affected side was smaller, with flattening at the posteromedial area and proximoposterior areas. 3D-MRI showed that the shape of the dislocated femoral head was aspherical with focal growth failure.

Relationship between glenoid deformity and gait characteristics in a rat model of neonatal brachial plexus injury

Neonatal brachial plexus injury (NBPI) results in substantial postural and functional impairments associated with underlying muscular and osseous deformities. We examined the relationship between glenoid deformity severity and gait in a rat model of NBPI, an established model for studying the in vivo pathomechanics of NBPI. At 8 weeks post-operatively, we monitored the gait of 24 rat pups who exhibited varying degrees of glenoid deformity following unilateral brachial plexus neurectomy and chemodenervation interventions administered 5 days postnatal. Five basic stride and stance metrics were calculated for the impaired forelimbs over four consecutive gait cycles. Bilateral differences in glenoid version (ΔGA_v ) and inclination (ΔGA_i ) angles were computed from data for the same rats as reported in a previous study. A linear regression model was generated for each deformity-gait pair to identify significant relationships between the two. ΔGA_v was not significantly correlated with any gait measurements, while ΔGA_i significantly correlated with all five gait measurements. Specifically, ΔGA_i was significantly positively correlated with stride length (R²  = 0.38, p = 0.001) and stance factor (R²  = 0.45, p < 0.001), and significantly negatively correlated with stance width (R²  = 0.24, p = 0.016), swing/stance ratio (R²  = 0.17, p = 0.046), and stride frequency (R²  = 0.33, p = 0.003). Rats with declined glenoids exhibited the most altered gait.

CLINICAL SIGNIFICANCE

Our findings link musculoskeletal changes and functional outcomes in an NBPI rat model. Thus, gait analysis is a potentially useful, non-invasive, quantitative way to investigate the effects of injury and deformity on limb function in the NBPI rat model. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1991-1997, 2018.

Guidelines for humeral subluxation cutoff values: a comparative study between conventional, reoriented, and three-dimensional computed tomography scans of healthy shoulders

BACKGROUND

The humeral subluxation index (HSI) is frequently assessed on computed tomography (CT) scans in conditions of the shoulder characterized by humeral displacement. An arbitrarily set HSI cutoff value of 45% for anterior subluxation and 55% for posterior subluxation has been widely accepted. We studied whether mean values and thresholds of humeral subluxation, in relation to the glenoid and scapula, were influenced by different imaging modalities.

METHODS

The HSIs referenced to the scapula (SHSI) and glenoid (GHSI) were compared between conventional CT scans, CT scans reoriented into the corresponding reference plane (ie, scapular plane for the SHSI and glenoid center plane for the GHSI), and 3-dimensional (3D) CT reconstructions of 120 healthy shoulders. The 95% normal range determined the cutoff values of humeral subluxation.

RESULTS

The SHSI thresholds for conventional, reoriented, and 3D CT scans were 33%-61%, 44%-68%, and 49%-61%, respectively. A different mean SHSI was found for each imaging modality (conventional, 47%; reoriented, 56%; 3D, 55%; P ≤ .014), with the conventional SHSI showing an underestimation in 89% of the cases. GHSI thresholds for conventional, reoriented, and 3D CT scans were 40%-61%, 44%-56%, and 46%-54%, respectively. The mean GHSI did not differ between each imaging modality (conventional, 51%; reoriented, 50%; 3D, 50%; P = .146).

CONCLUSIONS

The SHSI and GHSI are susceptible to different imaging modalities with consequently different cutoff values. The redefined HSI cutoff values guide physicians in the evaluation of humeral subluxation in conditions characterized by humeral displacement, depending on the available image data.

The Effect of Scapular Position on Magnetic Resonance Imaging Measurements of Glenohumeral Dysplasia Caused by Neonatal Brachial Plexus Palsy

PURPOSE

Neonatal brachial plexus palsy (NBPP) frequently causes glenohumeral dysplasia. Quantification of this dysplasia on magnetic resonance imaging can determine the need for and the success of nonsurgical or surgical intervention. However, we hypothesize that the variable position of the scapula on the thorax between affected and unaffected shoulders affects dysplasia measurements.

METHODS

Magnetic resonance imaging studies were analyzed from 19 NBPP patients (ages 0.8-18 years; median, 2.4 years) without prior shoulder surgery. Three reviewers measured the glenoid version angle (GVA) and percentage of humeral head anterior to the midscapular line (PHHA) on standard axial images ("thoracic axial") and on reformatted axial images aligned perpendicular to the scapular plane ("scapular axial"), which corrects for scapulothoracic position. Scapular tilt and protraction were measured to assess their impact on the difference between thoracic and scapular GVA and PHHA measurements. Intra- and interrater reliability were calculated for GVA and PHHA on both views.

RESULTS

The GVA of the affected shoulder was significantly greater on thoracic than on scapular images, by an average of 5° and as much as 34°. The PHHA was significantly less in the affected shoulders on thoracic than on scapular images, by an average of 5% and as much as 33% of humeral head width. The difference in GVA, but not PHHA, between thoracic and scapular axial images in the affected shoulder correlated with scapular tilt. Unaffected shoulders showed no significant difference in GVA or PHHA between thoracic and scapular axial images. Interrater reliability ranged from fair to substantial and did not differ between thoracic and scapular images.

CONCLUSIONS

Thoracic axial images overestimate the severity of glenohumeral dysplasia in NBPP, owing at least in part to the variable position of the scapula on the thorax. This confounding effect must be considered in interpretation of axial quantitative measures of glenohumeral dysplasia in NBPP.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

Shoulder muscle atrophy and its relation to strength loss in obstetrical brachial plexus palsy

BACKGROUND

Treatment/prevention of shoulder muscle strength imbalances are major therapeutic goals for children with obstetrical brachial plexus palsy. The study aims were to characterize muscle atrophy in children/adolescents with unilateral obstetrical brachial plexus palsy, to quantify the agonist-antagonist muscle volume balance and the association between muscle volume and strength.

METHODS

Eight boys and four girls (age=12.1, standard deviation=3.3) participated in this case-control study. Three-dimensional magnetic resonance images of both shoulders were acquired. The unimpaired shoulder served as a reference. Volumes of deltoid, pectoralis major, supraspinatus, infraspinatus, teres major, subscapularis were calculated based on 3D models, derived through image segmentation. Maximal isometric torques were collected in six directions.

FINDINGS

All the major muscles studied were significantly atrophied. The teres major demonstrated the biggest difference in atrophy between groups (51 percentage points), the pectoralis major was the least atrophied (23 percentage points). The muscle volume distribution was significantly different between shoulders. Muscle volume could predict maximal voluntary isometric torques, but the regression coefficients were weaker on the impaired side (72% to 91% of the strength could be predicted in the uninvolved side and 24% to 90% in the involved side and external rotation strength could not be predicted).

INTERPRETATION

This study demonstrates muscle atrophy varied across all the main shoulder muscles of the glenohumeral joint, leading to significant muscle volume imbalances. The weaker coefficients of determination on the impaired side suggest that other variables may contribute to the loss of strength in addition to atrophy.

Glenoid morphology in obstetrical brachial plexus lesion: a three-dimensional computed tomography study

BACKGROUND

Obstetric brachial plexus lesion (OBPL) frequently leads to glenohumeral dysplasia, and excessive retroversion of the glenoid is among the best known developmental disturbances. Most analyses of the glenoid are based on 2-dimensional (D) imaging and do not address glenoid inclination or provide information on the glenoid in the sagittal plane. We aim to describe the 3-D deformity of the glenoid in children with OBPL.

METHODS

Preoperative computed tomography (CT) scans of the nonaffected and the affected scapula of 24 children (aged 5 to 12 years) with developmental disturbances after OBPL years were analyzed. The dimensions of the scapula and the deformation of the glenoid were visualized in 3-D.

RESULTS

The retroversion of the glenoid fossa was greater in all affected shoulders, and 2-D measurements significantly overestimated retroversion compared with angles measured in 3-D. The inclination of the glenoid fossa was altered, and a distal bony edge loss was observed on 3-D reformations in the sagittal plane. The reliability of the measured angles was excellent, and the κ agreement for the description of the glenoid form was substantial. Furthermore, the dimensions of the scapula were significantly smaller on the affected shoulders.

CONCLUSION

OBPL is indeed a 3-D disorder. Our measurements revealed excessive retroversion of the glenoid fossa, and the reliability of the 3-D CT measurements was superior to their 2-D counterparts. 3-D CT reformations of the glenoid in the coronal and the sagittal plane added further to 3-D understanding of glenoid morphology in OBPL. These new findings legitimatize a 3-D CT-based description of the glenoid deformities connected with OPBL.

Reliability of 3D upper limb motion analysis in children with obstetric brachial plexus palsy

Kinematics, measured by 3D upper limb motion analysis (3D-ULMA), can potentially increase understanding of movement patterns by quantifying individual joint contributions. Reliability in children with obstetric brachial plexus palsy (OBPP) has not been established.

OBJECTIVE

This study aimed to determine between session reliability and measurement errors of 3D-ULMA using the acromion method (AM) in children with OBPP.

APPROACH

Ten participants (mean 10 years, range 7-15 years, Narakas classification I-III) completed 3D-ULMA on two occasions, mean interval of 8.6 d (±2.8 d). Kinematic data were captured by a 4-CODA cx1 optoelectronic tracking system. Participants performed three trials of the modified Mallet scale tasks. Local coordinate systems, segment and joint rotations were defined as recommended by the International Society of Biomechanics. The intraclass correlation coefficient (ICC 2,K) and standard error of measurement (SEM) were calculated for task duration, range and joint angle at point of task achievement (PTA).

MAIN RESULTS

Results indicated poor reliability for spatiotemporal parameters and range. Moderate to excellent reliability at PTA was observed in 19/60 variables (ICC: 0.77-0.98; SEM: 3.5°-10.4°). The Abduction Task had the highest (ICC: 0.79-0.98; SEM: 3.5°-10.3°) with External Rotation the lowest reliability. Glenohumeral and thoracohumeral elevation had the most consistent reliability. Scapular protraction/retraction had consistently poor reliability (ICC: 0-0.72; SEM: 3.5°-10.2°) with axial rotation also poor (ICC: 0.00-0.91; SEM: 6.3°-32.8°). This study determined inconsistent test-retest reliability of 3D-ULMA, using AM, to track dynamic performance of functional tasks in children with OBPP. It is the first study to outline measurement error in this population. This information permits more reliable interpretation of future studies of kinematic patterns in children with OBPP.