Biometrical analysis of the shoulder joint regarding glenoid implant dimensions for arthroplasty

Purpose

Reduced bone stock and difficult intraoperative orientation are challenges in glenoid replacement surgery. New implant designs and methods for fixation, such as locking screws, extra-long central pegs and/or central compression screws are targeting these issues. The objective of this study is the analysis of the glenoid dimension regarding maximum central peg diameter and peg length (PL), and maximum screw length (SL) for glenoid fixation.

Methods

Retrospective analysis of magnetic resonance imaging (n = 50) scans. Measurement of the maximum inferior glenoid diameter (GD), SL, maximum length of a 9.9, 10 and 11.4 mm central peg (PL) in the transverse plane; glenoid version (GV), humeral head diameter (HHD). Two independent measurements.

Results

Mean age: 49.0 ± 15.7 years (17–80) (n = 20 female, 49.6 ± 16.0; n = 30 male, 48.6 ± 15.7). Mean values of measurement were GD: 28.9 ± 3.7 mm (21–39); SL: 34.1 ± 4.9 mm (26–44); PL 9.9 mm: 19.4 ± 4.3 mm (9–30); PL 10 mm: 19.0 ± 4.4 mm (8–30); PL 11.4 mm: 16.5 ± 4.1 mm (7–26) with significant gender differences (p = 0.001; p = 0.022; p = 0.001); GV: ?0.6° ± 4.9° (?10 to 11); HHD: 50.0 mm ± 4.9 (41–61). There was good correlation between PL and SL (r = 0.32, p = 0.024) and for GD and PL (r = 0.61, p = 0.001; r = 0.57, p = 0.001; r = 0.96, p = 0.001). The ratio of HHD and GD was very constant with 0.6 ± 0.07.

Conclusions

These data indicate the high interindividual variability of glenoid morphology including significant gender-related differences. The good correlation between humeral head size and GD and maximum central PL can be helpful for cases with reduced bone stock in decision-making about implant size and bone grafting.     

Instabilität des Glenohumeralgelenks

The force-fit glenohumeral joint is stabilized by a fine interaction of passive and active stabilizers. Only in this way is a painless harmonious and powerful movement in all directions feasible. Besides the genuine functional disorders of this interplay, structural lesions are common causes of instability symptoms and dislocations. The classification based on the direction of instability, the trauma history and the presence of hyperlaxity is commonly accepted. Alongside the thorough history of present complaints and skilful clinical examination including special instability test maneuvers, diagnostic imaging sets the course for therapeutic interventions. Ultrasound gives a status report about the rotator cuff whereas magnetic resonance imaging (MRI) and computed tomography (CT) illustrate the structural damage to the glenohumeral joint. A decision for operative therapy is based on patient age, sport level, profession, risk profile, personal requirements of the patient and the present structural lesions. Major bony glenoid lesions cannot be compensated and are considered an urgent indication for surgery. The absence of structural disorders and pronounced functional deficits of scapulo-humeral balance (often accompanied by multidirectional instability) is the domain of conservative treatment. Surgical therapy aims at anatomical reconstruction which can be achieved both with classic open and arthroscopic techniques whereas both have advantages and disadvantages. Based on careful consideration of the indications, modern therapeutic interventions can achieve a low risk of recurrence, high rates of return to sport and profession and improved future prospects regarding instability arthropathy in the long-term can be expected.     

Ultrasound diagnosis of the acromioclavicular joint

Although standardized sonographic techniques are available, the diagnostic capabilities of sonography in diseases and injuries of the acromioclavicular [AC] joint are not yet widely used. Nevertheless, standardized sonographic techniques are available for examining injuries and diseases of the AC joint. Analogous to X-ray techniques, the bony relations of the clavicle and the acromion can be displayed. Joint effusions and marginal alterations of the subchondral bone plate can be imaged. However, there is no reliable method to display the articular disc and the coracoclavicular ligaments. There is no reproducible method for displaying the articular disk. Tears of the deltoid and trapezius muscles and their common fascia are easily detectable in high-grade injuries of the AC joint. The differentiation between acjoint injuries, i.e. Rockwood II/Rockwood IV, is facilitated, which aids in therapeutic decision making. In combination with conventional X-ray examination, sonography of the AC joint can be used at low cost and is easy to learn.     

Chemonucleolysis using chymopapain and collagenase. 3-year results of a prospective randomized study]

100 patients were prospectively and randomized treated by chemonucleolysis either by collagenase (n = 50/400 ABC-U/disc) or by chymopapain (n = 50/4000 I.U.). The success rate after 1 year was 70% for collagenase and 78% after chymopapain, and 72%/80% after 3 years, respectively. Successful results increased significantly during the first year after treatment and remained stable after that point. After chymopapain, one case of successfully treated anaphylaxis (2%) occurred. After collagenase, 3 cases of secondary sequestrations were observed in cases with primarily closed discograms with intact dorsal longitudinal ligament.     

Measurement of human lumbar spine ligaments during loaded and unloaded motion

Length changes in the ligaments of human lumbar spine motion segments were investigated in order to find conditions under which unusual stress or stress reduction is found in the longitudinal ligaments and facet joint capsules. Flexibility measurements were performed under load. Increasing load and height reduction in the motion segment increases the flexibility. The anterior and posterior longitudinal ligament normally operate in the elastic part of their stress-strain curve. Destruction of the intervertebral disc leads to a dislocation of the centers of rotation in the motion segment. Two types of facet joint capsules were observed. Height reduction in the motion segment leads to abnormal strains in one type sooner than in the other, which can be normalized by slight flexion. Injection of a silicone compound into the disc normalizes many of the changes in the motion segment due to height reduction.     

18-Jahres-Nachuntersuchung nach offener RM-Rekonstruktion

Objective

Age is a known factor for the emergence of a rotator cuff (RC) tear. Our goal was to determine whether a known supraspinatus tendon rupture represents a predisposition to a defect of the contralateral side.

Methods

We studied 37 patients, all who had undergone surgery by the same surgeon from May 1995 to January 1999. To be included, at least one pulley suture had to be used to reattach the affected tendon. All patients were already part of an follow-up examination for an average of 7.5 years postoperatively (range 4.8–10.2 years). Currently, patients were evaluated using the Constant score (CS), ASES, DASH, SPADI, WORC, and Oxford score. Sonography was also performed on both sides.

Results

Demographics: 24 men and 13 women, mean age 76 years, average time since surgery: 17.5 years. Two patients had already undergone RC reconstruction on both sides during the period 1995–1999. The rerupture rate on the surgical side 7.5 years postoperatively was 3?%, while on the contralateral side 9?% of patients had a nontreated RC defect. After 17.5 years, 17 of 37 patients (46?%) had contralateral RC defect surgery, and 6 (16.2?%) patients had an untreated contralateral side defect. Overall, 62.2?% of the patient collective had a defect on the contralateral side over a period of 17.5 years. After 7.5 years, the CS of the surgical side with 79.6 (age- and sex-adapted 102.7?%) was significantly improved, while on the contralateral side it was 77.4 (101.95?%). After 17.5 years, the CS was 76.6 (106.2?%) for the treated side and 73 (101.8?%) for the contralateral side.

Conclusion

We found that a surgically treated RC defect represents an increased risk for a defect of the contralateral side. Most defects of the contralateral side were symptomatic on average about 10 years after the primary surgery and were surgically treated.

     

Magnetic resonance tomography in spondylolysis and spondylolisthesis

40 patients with spondylolisthesis and/or spondylolysis were studied by magnetic resonance imaging (MR), 12 of whom with correlation to CT. CT proved to be more sensitive in detecting pars defects than MR. Sagittal MR, however, was more accurate in assessing spondylolisthesis than axial CT. At present, CT is superior to MR in demonstrating bony abnormalities. MR appears indicated in the patient undergoing spinal fusion in whom detection of intervertebral disc degeneration in the levels above or below intended fusion may lead to extension of fusion to the degenerated levels. Lack of ionizing radiation makes MR an ideal diagnostic method in evaluating spondylolisthesis in children and adolescents.