Alteration in stress distribution patterns through the elbow joint in professional and college baseball pitchers: Using computed tomography osteoabsorptiometry

Computed tomography Osteoabsorptiometry: Review of bone density, mechanical strength of material and clinical application

Computed Tomography (CT) imaging is an effective non-invasive examination. It is widely used in the diagnosis of fractures, arthritis, tumor, and some anatomical characteristics of patients. The density value (Hounsfield unit, HU) of a material in computed tomography can be the same for materials with varying elemental compositions. This value depends on the mass density of the material and the degree of X-ray attenuation. Computed Tomography Osteoabsorptiometry (CTOAM) imaging technology is developed on the basis of CT imaging technology. By applying pseudo-color image processing to the articular surface, it is used to analyze the distribution of bone mineralization under the articular cartilage, evaluate the position of prosthesis implantation, track the progression of osteoarthritis, and determine the joint injury prognosis. Furthermore, this technique was combined with indentation testing to discuss the relationship between the high bone density area of the articular surface, the mechanical strength of the bone, and the anchorage stability of the implant, in addition to the study of the relationship between mechanical strength and bone density. This narrative study discusses the pre- and postoperative evaluation of medical device implantation position, orthopedic surgery, and the clinical treatment of bone injury and degeneration. It also discusses the research status of CTOAM technology in image post-processing engineering and the relationship between bone material and mechanical strength.

Radial Head Lag: A Possible Biomechanical Mechanism for Osteochondritis Dissecans of the Capitellum in Baseball Pitchers

BACKGROUND

Osteochondritis dissecans (OCD) of the capitellum is common in throwing athletes and is believed to result from repetitive overloading on the radiocapitellar (RC) joint, although the cause and mechanism remain unclear. The torsional forces (moments) generated by the triceps during elbow extension pull only on the ulna; therefore, the radial head moves passively across the capitellum and is effectively "dragged along" by the ulna. Any laxity in the proximal radioulnar joint could lead to asynchronous motion between the radius and ulna, resulting in the radial head lagging behind the coronoid and possibly malarticulating with the capitellum during such motion.

HYPOTHESIS

Radial head motion on the capitellum lags behind ulnohumeral joint motion during simulated throwing.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 8 cadaveric elbows were tested under simulated throwing, including active extension of the elbow generated by pulling of the triceps under valgus stress, as well as during passive extension under valgus stress to serve as a reference. Ulnohumeral motion was tracked using a video camera. Radial head motion was tracked using an intra-articular, thin-film pressure sensor mounted on the capitellum, and the longitudinal movement of the center of force (COF) of the radial head was measured. Radial head motion was compared between passive and active motion for each 10° of elbow extension from 90° to 20°.

RESULTS

Elbow motion during simulated active extension reached an angular velocity of 366 deg/s. Radial head motion during simulated active extension significantly lagged compared with its motion during passive extension at every elbow extension angle examined between 70° and 20° (P < .001). The maximal lag reached a mean of 4 mm (range, 2-7 mm). In other words, RC and ulnohumeral motion were asynchronous during simulated throwing.

CONCLUSION

This study describes a novel phenomenon: motion of the radial head across the capitellum during rapid extension, such as in baseball pitching, lags behind that seen during passive elbow motion. According to a new proposed theory of OCD lesion development, this lag should result in RC incongruency and elevated shear forces on the capitellum due to edge loading.

CLINICAL RELEVANCE

We propose a new biomechanical explanation for OCD of the capitellum in baseball pitchers: radial head lag. Understanding this process is the first step in efforts to prevent this common injury.

Stress distribution pattern in the distal radioulnar joint before and after ulnar shortening osteotomy in patients with ulnar impaction syndrome

Ulnar shortening osteotomy (USO) for ulnar impaction syndrome potentially leads to degenerative changes of the distal radioulnar joint (DRUJ). This study was performed to evaluate the effect of the sigmoid notch morphology on the stress distribution pattern of the DRUJ using computed tomography (CT) osteoabsorptiometry (CT-OAM). We reviewed the pre- and postoperative transverse CT images of 15 wrists that had undergone USO. The examined wrists were classified into two groups based on the sigmoid notch morphology: the linear-type notch (type L) and the curved-type notch (type C). We calculated and statistically compared the percentage of the high-density area (%HDA) in each divided region of the sigmoid notch. In type L, %HDA was significantly larger in the distal-dorsal region of the sigmoid notch before USO. Postoperatively, in type L, no specific regions showed a significantly different %HDA. In type C, %HDA was significantly larger in the distal-volar region of the sigmoid notch before USO. Postoperatively, %HDA of type C was significantly larger in the proximal-volar region. Our results suggest that in patients with ulnar impaction syndrome, morphological evaluation of the sigmoid notch can serve as a predictor of osteoarthritis in the DRUJ with or without USO.

Stress-Distribution Pattern Across the Glenohumeral Joint in Collegiate and Professional Baseball Players: A Computed Tomography Osteoabsorptiometry Study

Background:

The influence of long-term loading conditions on the articular surfaces of the glenohumeral joint can be determined by measuring stress-distribution patterns. Long-term pitching activity changes the stress distribution across the glenohumeral joint surface; however, the influence of competitive level on stress-distribution patterns remains unclear.

Purpose:

To use computed tomography (CT) osteoabsorptiometry (CTOAM) to evaluate the distribution of subchondral bone density across the glenohumeral joint in collegiate and professional baseball players as well as to determine the effects of pitching activity on the articular surfaces.

Study Design:

Descriptive laboratory study.

Methods:

We evaluated 73 shoulders in 50 baseball players. CT imaging data were obtained from the dominant-side shoulder of 12 professional pitchers (PP group) and 15 professional fielders (PF group). CT imaging data were also obtained from both shoulders of 12 asymptomatic collegiate pitchers (CP group) and 11 collegiate fielders (CF group). The pattern of distribution of subchondral bone density across the articular surfaces of each glenohumeral joint was assessed by CTOAM. As a measure of bone density, the mean Hounsfield units (HU) were obtained for each joint surface, and the absolute values of the dominant shoulder were compared for each group.

Results:

Stress-distribution patterns over the articular surfaces differed between the dominant and nondominant sides in the CP group as well as between both collegiate groups versus the PP group. In the CP group, the mean HU of the humeral head surface were greater on the nondominant versus dominant side (P = .035). On the dominant side, the mean HU of the humeral head surface and glenoid were greater in the CP versus the PP group (P = .001 and .027, respectively).

Conclusion:

Stress distribution on the articular surface of the glenohumeral joint was affected by pitching ability and competitive level. Our analysis indicates that the traction force on the glenohumeral joint surface might be greater than compression force during pitching.

Clinical Relevance:

The present findings suggest that pitching activity results in low stress to the articular surfaces of the glenohumeral joint. This supports the notion that mechanical conditions play a crucial role in the etiology of disorders specific to pitching activity.

Long-term Stress Distribution Patterns Across the Ankle Joint in Soccer Players: A Computed Tomography Osteoabsorptiometry Study

Background:

The distribution pattern of subchondral bone density is considered to accurately reflect the stress distribution over a joint under long-term physiologic loading. The biomechanical characteristics of the surface of the ankle joint in soccer players can be determined by measuring this distribution pattern under long-term loading.

Purpose:

To evaluate the distribution of subchondral bone density across the ankle joint in soccer players and to determine the effects of soccer activities, including kicking motion, on the ankle joint surface under long-term loading conditions by computed tomography (CT) osteoabsorptiometry (CTOAM).

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

CT imaging data were obtained from both ankles of 10 soccer players (soccer group) and 10 nonathletic volunteers (control group). The distribution patterns of subchondral bone density across the articular surface of the ankle joints were assessed by CTOAM. Quantitative analysis was performed of the locations and percentages of high-density areas on the articular surface.

Results:

Stress distribution patterns over the ankle joint differed between the soccer players and controls. In the soccer players, the high-density areas were found in the anterior part of the distal tibia and proximal talus as well as the distal fibula. The percentages of high-density areas were greater in the soccer players compared with controls (P < .0001).

Conclusion:

Stress distribution over the articular surface of the ankle joint was affected by soccer activities. A high stress concentration was seen in soccer players in the anterior part of the tibia and talus and in the fibula; such excessive stress may lead to anterior impingement.