Physeal Injuries of the Coracoid Process Are Closely Associated With Sports Activities: A Systematic Review

Background:

Physeal injuries of the coracoid process are rare but may be increasing because of increased participation of youth in year-round sports.

Purpose:

To analyze reported physeal and apophyseal injuries of the coracoid process.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

PubMed and Scopus were searched using the terms scapula fracture and coracoid fracture. The inclusion criteria were English full-text articles describing coracoid fracture as well as articles that described patient characteristics and presented appropriate images. The exclusion criteria were descriptive cases without images as well as those lacking appropriate images. Citation tracking was conducted to find additional articles and full-text articles written in other languages. Articles were included if they reported physeal injury or judged to involve physeal injury based on the provided images.

Results:

Overall, 22 studies including 32 patients (29 males, 3 females) were identified. All but 2 patients were younger than 18 years of age, and 66% (21/32) had sustained injuries during or as a result of participation in sporting activities. The affected site was the physis at the base in 18 patients, an intra-articular fracture in the primary coracoid ossification center combined with the subcoracoid ossification center to form an intra-articular fracture in 5, the apophysis of the tip in 3, the apophysis of the angle in 5, and uncertain in 1. Eleven patients had concurrent acromioclavicular injuries. The injury was acute in 23 patients, chronic in 6, and traumatic nonunion in 3. Among 21 cases in which treatment methods and outcomes were described, 21% of the acute cases (4/19), and 2 of the 3 nonunions were surgically treated. Only 1 study used a widely accepted evaluation method. Follow-up periods ranged from 6 weeks to 2 years. Outcomes were generally excellent for nonoperative and operative treatment and without any serious complications.

Conclusion:

Coracoid physeal injuries occurred most commonly in patients aged 13 to 15 years of age (71%) and were usually sustained during or as a result of sports activities (66%). The most common injury site was the physis at its base. The cause of these injuries is probably severe or repeated traction of the attached muscles and ligaments. The majority of these injuries can be successfully treated nonoperatively.

Seasonal variation in the onset of acute calcific tendinitis of rotator cuff

Background

Calcific tendinitis of the rotator cuff is a disorder that causes acute onset of shoulder pain when spontaneous resorption of the calcification occurs. However, factors that trigger calcium resorption have not been clarified. The present study aimed to investigate the association between the onset of calcium resorption in calcific tendinitis and the season of onset.

Methods

We retrospectively reviewed 195 patients (female, 116; male, 79; mean age, 62.6 ± 14.2 years; median age, 62 [52, 73] years) diagnosed with the postcalcification stage of calcific tendinitis, which was defined as acute calcific tendinitis in this study, between 2006 and 2018. The onset date of acute calcific tendinitis for each patient was collected from clinical notes. We evaluated the incidence of acute calcific tendinitis in each season and month. Furthermore, we investigated the correlation between the incidence of acute calcific tendinitis and the mean monthly temperature or humidity levels for each year.

Results

The most common season of acute calcific tendinitis onset was summer (35.4%), followed by spring (24.6%), autumn (24.1%), and winter (15.9%) (P = 0.002). Monthly analyses showed the highest peak of onset was in July (15.4%) and the lowest peak was in February (3.1%) (P = 0.022). The incidence of acute calcific tendinitis had a weak association with mean monthly temperature (R² = 0.066; P = 0.001) but was not associated with mean monthly humidity levels (R² = 0.018; P = 0.099).

Conclusions

This study provides new information on seasonal variation of acute calcific tendinitis onset. The results of this study indicated that the onset of calcium resorption occurs most frequently in the summer in Japan; however, the reasons for seasonal variation remain unclear, and further studies will be needed.

Level of evidence

Level III.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03773-6.

Volar transfer of the lateral band with transverse retinacular ligament is effective for the correction of swan-neck deformity caused by volar plate injury of the PIP joint

We introduced a technique with a volar transfer of the lateral band using the transverse retinacular ligament for swan-neck deformity caused by volar plate injury of the PIP joint. A 61-year-old woman injured her 5th finger and was diagnosed with a volar plate injury of the PIP joint. She presented with snapping of the finger together with the appearance of a swan-neck deformity, and surgery was performed. Dorsally located lateral bands were transferred towards the volar aspect of the finger, and their position was maintained using the transverse retinacular ligament. Improvements in the snapping and swan-neck deformities were confirmed by intraoperative active motion of the finger. One year postoperatively, the deformity had not recurred, and there was no contracture of the finger. Surgical transfer of the lateral band using the transverse retinacular ligament is effective for swan-neck deformity caused by volar plate injury of the PIP joint.

Reproducibility of the modified Neer classification defining displacement with respect to the humeral head fragment for proximal humeral fractures

Background

Although the Neer classification is widely used for the assessment of proximal humeral fractures, its reproducibility has been challenged. The purpose of this study was to evaluate the reproducibility of the conventional Neer classification and a modified classification that defined fracture displacement with respect to the humeral head fragment.

Methods

The fracture patterns in 80 cases of proximal humeral fractures were independently assessed by 6 observers. The cases were grouped according to the conventional Neer classification using radiographs followed by computed tomography (CT) scans by each examiner twice with a 1-month interval. The fractures were then classified with the modified Neer classification, which defined displacement of the fragment as separation of more than 1 cm or angulation of more than 45° from the humeral head fragment, twice with a 1-month interval. Kappa coefficients of the conventional and modified Neer classifications were compared.

Results

The modified classification showed significantly higher intra-observer agreement than the conventional classification, both for radiographs (P = .028) and for CT scans (P = .043). Intra-observer agreement was also significantly higher for the modified classification than for the conventional classification, both for radiographs (P = .001) and for CT scans (P < .001).

Conclusions

The present study showed that agreement for the Neer classification could be improved when fracture displacement was defined as separation or angulation from the humeral head. Considering vascularity to the humeral head, furthermore, the modified method might be more helpful for predicting patients’ prognosis than the conventional Neer classification.

Pseudoaneurysm of the Posterior Humeral Circumflex Artery After Reverse Shoulder Arthroplasty: A Case Report

CASE

A 78-year-old woman with rheumatoid arthritis and a massive rotator cuff tear of the right shoulder was treated with reverse shoulder arthroplasty, but a pseudoaneurysm in the posterior humeral circumflex artery suddenly ruptured 7 months after surgery. Embolization of the pseudoaneurysm and skin treatment successfully relieved her symptoms without implant removal.

CONCLUSION

Although a rare occurrence, vascular complication can occur after shoulder arthroplasty. The cause of the pseudoaneurysm was hypothesized to be repetitive contact between the humeral component and the artery and/or chronic traction of the blood vessel because of its chronic onset.

Evaluation of three-dimensional acromiohumeral distance in the standing position and comparison with its conventional measuring methods

Background

Narrowing of the acromiohumeral distance (AHD) implies a rotator cuff tear. However, conventional AHD measurements using two-dimensional (2D) imaging or with the patient in the supine position might differ from that while standing during daily activity. This study aimed to evaluate the three-dimensional (3D) actual distance between the acromion and humeral head in the standing position and compare the AHD values with those obtained using conventional measuring methods.

Methods

Computed tomography (CT) images of 166 shoulders from 83 healthy volunteers (31 male and 52 female; mean age 40.1 ± 5.8 years; age range, 30–49 years) were prospectively acquired in the supine and standing positions using conventional and upright CT scanners, respectively. The minimum distance between the acromion and humeral head on the 3D surface models was considered as the 3D AHD. We measured the 2D AHD on anteroposterior digitally reconstructed radiographs. The AHD values were compared between the supine and standing positions and between the 2D and 3D measurements.

Results

The mean values of 2D AHD were 8.8 ± 1.3 mm (range, 5.9–15.4 mm) in the standing position and 8.1 ± 1.2 mm (range, 5.3–14.3 mm) in the supine position. The mean values of 3D AHD were 7.3 ± 1.4 mm (range, 4.7–14.0 mm) in the standing position and 6.6 ± 1.2 mm (range, 4.4–13.7 mm) in the supine position. The values of 3D AHD were significantly lower than those of 2D AHDs in both the standing and supine positions (P < 0.001). The values of 2D and 3D AHDs were significantly lower in the supine position than in the standing position (P < 0.001).

Conclusions

This study evaluated the 3D AHD of normal shoulders in the standing position using an upright CT scanner. The present results indicated that assessments in the supine position can underestimate the value of the AHD compared with those made in the standing position and that assessments using 2D analysis can overestimate the value.

Three-dimensional alignment changes of the shoulder girdle between the supine and standing positions

Background

Although humans spend most of their day in a standing or sitting position, it is difficult to accurately evaluate the alignment of the shoulder girdle during daily activity, and its alignment changes between positions. The purpose of this study was to evaluate the 3-dimensional alignment of the shoulder girdle in the supine and standing positions by computed tomography (CT) and to assess the alignment changes of the shoulder girdle between these two positions.

Methods

CT scans of both shoulders of 100 healthy volunteers were prospectively taken in both supine and standing positions on the same day. The local 3-dimensional coordinate systems of the thorax, clavicle, and scapula were defined from the specific bony landmarks, and 3-dimensional angular rotations and positions of the clavicle and scapula were calculated. Differences in rotations and positions of the clavicle and scapula were evaluated between the supine and standing positions.

Results

Compared with the supine position, the clavicle showed significantly less elevation and greater retraction, and the scapula showed significantly less upward rotation, anterior tilting, and internal rotation in the standing position. Compared with the supine position, the clavicle center was located more inferiorly, posteriorly, and laterally, and the scapula center was located more inferiorly, posteriorly, and medially in the standing position.

Conclusions

The present study showed that angular rotations and positions of the clavicle and scapula change significantly with position due to the effect of gravity.

Computed tomography-based three-dimensional preoperative planning for total wrist arthroplasty

Total wrist arthroplasty is indicated for severely damaged joints; however, it is sometimes difficult to place the implant in the proper position. We report a case of total wrist arthroplasty using computed tomography (CT)-based 3D planning. After a 3D digital model of the wrist was reconstructed using preoperative planning software, the computer-aided design models of the implant were superimposed on the wrist and the appropriate size and position of the implant were determined. During surgery, the planned parameters were measured using a slide gauge to reproduce the planned position of the implant. The size of the implant used at surgery was the same as in 3D planning. Comparing the CT before and after surgery, the position of the implant was almost the same as in 3D planning on the radial side, but the carpal side was placed 7 mm proximal to the position in preoperative planning. Two years after surgery, the patient had no complications and radiography showed no obvious signs of aseptic loosening. Our method may contribute to a reduced incidence of complications, such as intraoperative fracture and postoperative dislocation, leading to improve long-term outcomes of total wrist arthroplasty.

A Comparison of Splint Versus Pinning the Distal Interphalangeal Joint for Acute Closed Tendinous Mallet Injuries

Background: The vast majority of acute closed tendinous mallet injuries are treated with a splint. Very few studies have directly compared splinting versus pinning the distal interphalangeal joint for this injury. The aim of this cohort study is to determine the outcomes of both methods. Methods: A total of 59 patients with acute tendinous mallet injury were retrospectively enrolled (29 patients in conservative treatment and 30 patients in surgical treatment). Conservative treatment was performed using custom-made thermoplastic splint and surgical treatment was conducted with oblique K-wire fixation of the distal interphalangeal (DIP) joint. The DIP joint was immobilized for eight weeks in both treatments. Active ranges of motion of the affected finger and Miller's classification were evaluated postoperatively. Results: The mean extension lag of the DIP joint in the surgical treatment group was significantly better than it was with conservative treatment (2.1° vs 13.8°). Three patients who were noncompliant with the splint showed poor results, while no patients in the surgical treatment group had a poor result. Conclusions: Surgical treatment with K-wire fixation leads to satisfactory results for acute tendinous mallet injury.

A Case of Coronal Intra-articular and Epiphyseal Fractures of the Metacarpal Head in Early Adolescence

Intra-articular metacarpal head fracture is relatively rare. We report a case of coronal intra-articular and epiphyseal fractures of Salter-Harris type IV injury in the metacarpal head of the index finger. Surgery was performed by a dorsal approach. The volar fragment that was displaced proximally was gently reduced while bending the metacarpophalangeal (MP) joint, and it was fixed with cortical screws inserted proximal to the articular cartilage facilitating early rehabilitation. We consider the mechanism of injury to be a force applied from the distal phalanx that was transmitted unevenly to the volar side when the MP joint was slightly flexed. A three-dimensional computed tomography scan was useful in making the precise diagnosis, confirming the fracture pattern and planning fixation of the fracture.

Causes of Procedural Failures of Closed Reductions using an Extension-Block Pin for Bony Mallet Finger

This retrospective study evaluated procedural failures of closed reductions using an extension-block Kirschner wire (K-wire) for bony mallet finger. A total of 132 patients who underwent a closed reduction for bony mallet finger in a procedure using an extension-block K-wire were radiographically assessed. Radiographs were used to evaluate (1) postoperative displacement of the reduction before or after K-wire removal and (2) inaccurate reduction of the fragment immediately after surgery. The causes of procedural failure and bone union were evaluated using radiographs and medical records of the intraoperative findings. Out of 132 patients, 17 with procedural failure were enrolled. Displacement of the reduction before and after K-wire removal occurred in seven and six cases, respectively. Inaccurate reduction immediately after surgery occurred in four cases. The most common cause of procedural failure was inaccurate insertion of the K-wire to fix the distal interphalangeal joint (eight cases) followed by inaccurate insertion of the extension-block pin (five cases). All patients had bone union regardless of the displacement of the reduction or inaccurate reduction of the fragment. Caution should be exercised during the reduction and fixation when an extension-block K-wire is used in a closed reduction procedure.

Comparison between Trans-articular and Subacromial Stabilization with Ligament Repair for Acute Acromioclavicular Dislocation

Background:

Although numerous treatment options for acromioclavicular joint dislocation have been reported, the treatment strategy is not yet standardized.

Objective:

The purpose of this study was to evaluate the clinical and radiographic results of coracoclavicular ligament repair with temporary acromioclavicular stabilization using suture anchors and Kirschner wires, and to compare the results between temporary trans-articular fixation and subacromial stabilization of the acromioclavicular joint.

Methods:

Thirty-three cases with displaced acromioclavicular joint dislocation were retrospectively evaluated. In the first 14 cases, the wires temporarily penetrated the joint for an average of 7 weeks (trans-articular group), while the acromioclavicular joint was temporarily stabilized by wires passing under the acromion that were inserted into the distal clavicle for an average of 13 weeks in the latter 19 cases (subacromial group). Clinical and radiographic results were evaluated and compared between the two groups.

Results:

The average UCLA score was 32.0 points in the trans-articular group and 32.8 points in the subacromial group, indicating no difference between the two groups (P = 0.418). Coracoclavicular distance ratio after surgery was significantly smaller in the subacromial group (P ≤ 0.035), and acromioclavicular dislocation ratio after removal of the wires was also smaller in the subacromial group (P ≤ 0.001) compared with the trans-articular group.

Conclusion:

This study revealed that coracoclavicular ligament repair with temporary acromioclavicular stabilization leads to favorable clinical results, with the subacromial group showing better maintenance of joint reduction compared with the trans-articular group. Subacromial wire stabilization is a viable option for long-term temporary fixation of acute displaced acromioclavicular joint dislocation.

Treatment of distal clavicle fractures using a Scorpion plate and influence of timing on surgical outcomes: a retrospective cohort study of 105 cases

Background

Plate fixation is an established method for treating unstable distal clavicle fractures. However, the appropriate timing of surgery for acute distal clavicle fractures remains unclear. The present study aimed to evaluate the clinical outcomes of osteosynthesis using a Scorpion plate and to assess the influence of surgery timing on the surgical outcomes for acute unstable distal clavicle fractures.

Methods

We retrospectively reviewed 105 patients who underwent fixation for acute unstable distal clavicle fractures (Neer type II and V) using the Scorpion plate between 2008 and 2018. Patients were divided into early (45 patients) and delayed (60 patients) treatment groups based on the timing of the surgical intervention (within or after 7 days). The outcomes were postoperative complications (nonunion, peri-implant fracture, plate loosening, plate-related pain, and stiffness). We evaluated the outcomes from X-ray radiographs and clinical notes.

Results

Among the 105 patients, nonunion, plate loosening, plate-related pain, and stiffness were observed in six patients (5.7%), four patients (3.8%), seven patients (6.7%), and one patient (1.0%), respectively. The nonunion rate was significantly higher in the delayed treatment group than that in the early treatment group (P = 0.036). Although the difference was not significant, plate loosening and stiffness were only observed in the delayed treatment group.

Conclusion

Our results demonstrated that osteosynthesis using Scorpion plates achieved satisfactory surgical outcomes for unstable distal clavicle fractures. In addition, this study suggested that performing surgery within 6 days after injury is recommended to reduce postoperative complications.

Clinical Results of Surgical Resection and Histopathological Evaluation of Synovial Chondromatosis in the Shoulder: A Retrospective Study and Literature Review

Background

Synovial chondromatosis occurs rarely in the shoulder, and its details remain unclear. The purpose of this study was to clarify the clinical results of surgical resection and the histopathological findings of synovial chondromatosis in the shoulder.

Methods

Ten shoulders with synovial chondromatosis that had been operatively resected were reviewed retrospectively. Osteochondral lesions were present in the glenohumeral joint in six shoulders and in the subacromial space in four shoulders. Two patients had a history of trauma with glenohumeral dislocation without recurrent instability, and the other seven patients (eight shoulders) did not have any traumatic episodes or past illness involving the ipsilateral shoulder girdle. The occurrences of osteochondral lesions, inferior humeral osteophytes, and acromial spurs were assessed on radiographs before resection, just after resection, and at final follow-up. The Constant scores were compared before resection and at final follow-up with Wilcoxon signed-rank tests. Resected lesions were histopathologically differentiated between primary and secondary synovial chondromatosis.

Results

Inferior humeral osteophytes were found in five shoulders with synovial chondromatosis in the glenohumeral joint, and all four shoulders with synovial chondromatosis in the subacromial space had acromial spur formation. Osteochondral lesions appeared to have been successfully removed in all shoulders on postoperative radiographs. At the final follow-up, however, one shoulder with secondary synovial chondromatosis in the subacromial space showed recurrence of osteochondral lesions and acromial spur formation. The mean Constant score improved significantly from 53.0 points before resection to 76.0 points at a mean follow-up of 6.0 years (p = 0.002). On histopathological evaluation, one shoulder was diagnosed as having primary synovial chondromatosis, while nine shoulders had secondary synovial chondromatosis.

Conclusions

The present study showed that resection of shoulder osteochondral lesions successfully relieved the clinical symptoms and that primary synovial chondromatosis is less common than secondary synovial chondromatosis in the shoulder. Although most of the present osteochondral lesions were clinically determined to be primary chondromatosis, only one case was histopathologically categorized as primary synovial chondromatosis. These results suggest that histopathological identification is needed to differentiate between primary and secondary synovial chondromatosis.

Continuous Catheter Irrigation for the Treatment of Purulent Tenosynovitis during Two-Stage Flexor Tendon Reconstruction

Two-stage flexor tendon reconstruction with a silicone rod is useful for restoring the tendon and tendon sheath but sometimes results in infection after the first-stage operation. We experienced a case in which we maintained the reconstructed tendon sheath by replacing an infected silicone rod with a polyvinyl chloride tube, followed by continuous catheter irrigation until the infection subsided. This procedure can effectively deal with infection of a silicone rod during two-stage flexor tendon reconstruction.

Cerclage Wiring Fixation for the Treatment of Long Oblique Fractures of the Distal Clavicle: A Report of 2 Cases

CASE

A 49-year-old man and a 37-year-old man with long oblique fractures of the distal clavicle were successfully treated with cerclage wiring fixation without detachment of the trapezius and deltoid muscles and exposure of the fracture site.

CONCLUSIONS

Long oblique fractures with the acromioclavicular and coracoclavicular ligaments being intact and attached to the distal fragment are relatively rare among distal clavicle fractures. Cerclage wiring fixation is a viable treatment option for the fixation of long oblique fractures of the distal clavicle, with good clinical results and rapid recovery of shoulder function.

Four-Dimensional CT Analysis Using Sequential 3D-3D Registration

Four-dimensional computed tomography (4DCT) provides a series of volume data and visualizes joint motions. However, numerical analysis of 4DCT data remains difficult because segmentation in all volumetric frames is time-consuming. We aimed to analyze joint kinematics using a sequential 3D-3D registration technique to provide the kinematics of the moving bone with respect to the fixed bone semiautomatically using 4DCT DICOM data and existing software. Surface data of the source bones are reconstructed from 3DCT. The trimmed surface data are respectively matched with surface data from the first frame in 4DCT. These trimmed surfaces are sequentially matched until the last frame. These processes provide positional information for target bones in all frames of the 4DCT. Once the coordinate systems of the target bones are decided, translation and rotation angles between any two bones can be calculated. This 4DCT analysis offers advantages in kinematic analyses of complex structures such as carpal or tarsal bones. However, fast or large-scale motions cannot be traced because of motion artifacts.

Glenohumeral translation during active external rotation with the shoulder abducted in cases with glenohumeral instability: a 4-dimensional computed tomography analysis

BACKGROUND

Although glenohumeral instability is common, the mechanism of instability remains unclear. The purpose of this study was to quantitatively evaluate humeral head translation during active external rotation with abduction in patients with glenohumeral instability by use of 4-dimensional computed tomography scans.

METHODS

Ten patients with unilateral glenohumeral instability with a positive fulcrum test were prospectively included in this study. Sequential computed tomography of bilateral shoulders during active external rotation at 90° of shoulder abduction was performed for 6 seconds at 5 frames per second. The 3-dimensional positions of the humeral head center in the anteroposterior, superoinferior, and mediolateral directions were calculated at 0°, 20°, 40°, 60°, and maximum shoulder abduction-external rotation from the starting position. Translation of the humeral head center from the starting position was evaluated using Dunnett multiple-comparison tests, and the differences between the affected and intact shoulders were assessed using Wilcoxon signed rank tests.

RESULTS

The humeral head center translated posteriorly, inferiorly, and medially during glenohumeral external rotation with the shoulder in the abducted position on the intact side. However, the affected humeral head showed significantly less posterior translation (P = .028), greater inferior translation (P = .047), and less medial translation (P = .037) than the contralateral side.

CONCLUSIONS

This study indicated that dysfunction of the anterior band of the inferior glenohumeral ligament causes decreased posterior, increased inferior, and decreased medial translation of the humeral head during active shoulder abduction-external rotation.

A novel pyrenophane bearing tetraazathiapentalene skeleton

A novel pyrenophane incorporating macrocyclic tetraazathiapentalene is synthesised and characterised. The absorption and fluorescence spectra in CH2Cl2 clearly showed π–π interaction between two pyrene rings including pyrene excimer emission.

Total finger joint arthroplasty with a costal osteochondral autograft: up to 11 years of follow-up

The purpose of this study was to evaluate the mid- to long-term clinical outcomes of total finger joint arthroplasty using a costal osteochondral autograft for joint ankylosis. Twenty-three joints (three metacarpophalangeal joints, 20 proximal interphalangeal joints) in 23 patients (19 men and four women) were treated with a costal osteochondral autograft and were evaluated after a mean follow-up of 77 months (60-138). Mean age was 33 years (18 to 55). Significant improvement in active finger extension/flexion was seen from a preoperative mean of -24°/26° (arc: 2°) to -13°/75° (arc: 63°) at latest follow-up. Mean preoperative Japanese Society for Surgery of the Hand version of the Disability of the Arm, Shoulder and Hand score was initially 24 and improved significantly to 5 at latest follow-up. Conclusion: total finger arthroplasty using a costal osteochondral autograft gave an anatomical and biological reconstruction and provided stable improvement at a mean follow-up of 77 months. Level of evidence: IV.

A computed tomography analysis of three-dimensional glenoid orientation modified by glenoid torsion

Background

The longitudinal axis of the glenoid is not always parallel to the scapular body, and glenoid torsion could affect the values of glenoid orientation. The purpose of this study was to evaluate 3-dimensional glenoid version and inclination modified by glenoid torsion and to clarify the differences between the values of conventional and of modified glenoid orientations.

Methods

Computed tomography scans of 30 shoulders without shoulder pathology, 30 shoulders with primary osteoarthritis, and 30 shoulders with a massive rotator cuff tear or cuff tear arthropathy were retrospectively evaluated. After determining the glenoid axis and the scapular planes and calculating conventional glenoid version and inclination, modified glenoid version and inclination, and glenoid torsion, the values of conventional glenoid orientation and those of modified glenoid orientation were compared statistically.

Results

All shoulders showed anterior torsion of the glenoid with an average of 16° ± 5°. The values of modified glenoid retroversion were significantly smaller than those of conventional glenoid retroversion in all groups (P < .033), and the values of the modified glenoid inferior inclination were significantly larger than those of conventional glenoid inferior inclination in all groups (P < .001).

Conclusions

The present study showed that the glenoid twists with respect to the scapular body and that modification by glenoid torsion could affect the values of glenoid orientation. These results indicated that glenoid orientation with respect to the glenoid longitudinal axis will help surgeons determine proper placement of the glenoid component during shoulder arthroplasty.

The relationship between the morphological axis and the kinematic axis of the proximal radius

PURPOSE

Surgical procedures for impaired forearm rotation such as for chronic radial head dislocation remain controversial. We hypothesized that the morphological axis of the proximal radius is important for stable forearm rotation, and we aimed to clarify the relationship between the morphological axis and the kinematic axis of the proximal radius using four-dimensional computed tomography (4DCT).

METHODS

Ten healthy volunteers were enrolled. Four-dimensional CT of the dominant forearm during supination and pronation was obtained. The rotation axis of forearm rotation was calculated from all frames during supination and pronation. The principle axis of inertia, which represents the most stable rotation axis of a rigid body, was calculated for the proximal radius by extending its surface data incrementally by 1% from the proximal end. The angle between the kinematic rotation axis and the morphological rotation axis of each length was calculated.

RESULTS

The rotation axis of the forearm was positioned on the radial head 0.0 mm radial and 0.4 mm posterior to the center of the radial head proximally and 2.0 mm radial and 1.2 mm volar to the fovea of the ulnar head distally. The principle axis at 15.9% of the length of the proximal radius coincided with the forearm rotation axis (kinematic axis). Individual differences were very small (SD 1.4%).

CONCLUSION

Forearm rotation was based on the axis at 16% of the length of the proximal radius. This portion should be aligned in cases of severe morphological deformity of the radial head that cause "rattling motion" of the radial head after reduction procedures.