Advanced MR imaging of the shoulder: dedicated cartilage techniques

Treatment of Articular Cartilage Injuries in the Glenohumeral Joint

Articular cartilage injuries in the glenohumeral joint present a unique and difficult problem for the patient and surgeon alike. Various etiologies exist for the development of these cartilage lesions; therefore, treatment options are vast and must be chosen thoughtfully, especially in the young, active patient. Across all treatment modalities, the goal is for the patient to regain lasting function and mobility while decreasing pain.

Diagnostic performance of CT-arthrography and 1.5T MR-arthrography for the assessment of glenohumeral joint cartilage: a comparative study with arthroscopic correlation

PURPOSE

To compare the diagnostic performance of multi-detector CT arthrography (CTA) and 1.5-T MR arthrography (MRA) in detecting hyaline cartilage lesions of the shoulder, with arthroscopic correlation.

PATIENTS AND METHODS

CTA and MRA prospectively obtained in 56 consecutive patients following the same arthrographic procedure were independently evaluated for glenohumeral cartilage lesions (modified Outerbridge grade ≥2 and grade 4) by two musculoskeletal radiologists. The cartilage surface was divided in 18 anatomical areas. Arthroscopy was taken as the reference standard. Diagnostic performance of CTA and MRA was compared using ROC analysis. Interobserver and intraobserver agreement was determined by κ statistics.

RESULTS

Sensitivity and specificity of CTA varied from 46.4 to 82.4 % and from 89.0 to 95.9 % respectively; sensitivity and specificity of MRA varied from 31.9 to 66.2 % and from 91.1 to 97.5 % respectively. Diagnostic performance of CTA was statistically significantly better than MRA for both readers (all p ≤ 0.04). Interobserver agreement for the evaluation of cartilage lesions was substantial with CTA (κ = 0.63) and moderate with MRA (κ = 0.54). Intraobserver agreement was almost perfect with both CTA (κ = 0.94-0.95) and MRA (κ = 0.83-0.87).

CONCLUSION

The diagnostic performance of CTA and MRA for the detection of glenohumeral cartilage lesions is moderate, although statistically significantly better with CTA.

KEY POINTS

• CTA has moderate diagnostic performance for detecting glenohumeral cartilage substance loss. • MRA has moderate diagnostic performance for detecting glenohumeral cartilage substance loss. • CTA is more accurate than MRA for detecting cartilage substance loss.

Treatment of glenohumeral arthrosis

The successful diagnosis and treatment of glenohumeral arthrosis in the young and active patient can be challenging to even the most experienced of clinicians. A thorough preoperative evaluation, including a detailed understanding of patient expectations, facilitates the selection of a treatment strategy. Arthroscopy is the gold standard for detecting chondral injuries, and it is increasingly used as an effective first line of management. In patients who fail arthroscopic debridement and reparative techniques, further treatment should proceed with an algorithmic decision-making approach encompassing patient-based and disease-based factors. Restorative and reconstructive techniques may provide improvements in pain and functional outcome while delaying the need for total shoulder arthroplasty, although the longevity of these treatments has yet to be established in the literature. Hemiarthroplasty and total shoulder arthroplasty have historically proven to be the most durable and reliable options in properly selected patients. However, concerns about progressive glenoid erosion and glenoid component loosening have led many to pursue alternative nonarthroplasty techniques for the management of arthrosis in active young individuals.

Glenohumeral joint preservation: current options for managing articular cartilage lesions in young, active patients

This is a review of joint-preservation techniques for the shoulder. Whereas the management of diffuse articular cartilage loss in the glenohumeral joints of elderly and less active patients by total shoulder arthroplasty is well accepted, significant controversy persists in selecting and refining successful operative techniques to repair symptomatic glenohumeral cartilage lesions in the shoulders of young, active patients. The principal causes of focal and diffuse articular cartilage damage in the glenohumeral joint, including previous surgery, trauma, acute or recurrent dislocation, osteonecrosis, infection, chondrolysis, osteochondritis dissecans, inflammatory arthritides, rotator cuff arthropathy, and osteoarthritis, are discussed. Focal cartilage lesions of the glenohumeral joint are often difficult to diagnose and require a refined and focused physical examination as well as carefully selected imaging studies. This review offers a concise guide to surgical decision making and up-to-date summaries of the current techniques available to treat both focal chondral defects and more massive structural osteochondral defects. These techniques include microfracture, osteoarticular transplantation (OATS [Osteochondral Autograft Transfer System]; Arthrex, Naples, FL), autologous chondrocyte implantation, bulk allograft reconstruction, and biologic resurfacing. As new approaches to glenohumeral cartilage repair and shoulder joint preservation evolve, there continues to be a heightened need for collaborative research and well-designed outcomes analysis to facilitate successful patient care.

Glenohumeral Microfracture

The treatment of symptomatic cartilage lesions in the glenohumeral joint presents a significant challenge due to poor healing characteristics. Diagnosis of glenohumeral chondral defects is not always clear, and while current imaging modalities are good, many lesions require arthroscopy to fully appreciate. Arthroplasty remains an effective treatment in low-demand patients; however, younger, higher demand individuals may be treated with less invasive reparative measures. This paper discusses the diagnosis of glenohumeral chondral pathology and presents the technique, rehabilitation, and available outcomes following microfracture in the shoulder.

Nonarthroplasty alternatives for the treatment of glenohumeral arthritis

Although most glenohumeral cartilaginous lesions are incidental findings and well tolerated, a symptomatic cartilage injury in a young, active individual remains a challenge. The diagnosis of this symptomatic lesion is difficult, and is usually only arrived at once other shoulder comorbidities and sources of glenohumeral pain are ruled out. Once diagnosed, a variety of treatment options are available which include palliative, reparative, restorative, and reconstruction techniques. The smallest lesions are amenable to reparative strategies such as marrow-stimulation, stimulating a fibrocartilaginous response. Larger lesions and those that have failed reparative techniques may be candidates for restorative or reconstruction procedures to replace damaged cartilage with hyaline-like tissue. The presence of bipolar injury may require the use of biologic interpositional arthroplasty. This review describes the challenges associated with the diagnosis and management of glenohumeral arthritis, and provides a treatment framework for use in these challenging patients.

Sodium and T1rho MRI for molecular and diagnostic imaging of articular cartilage

In this article, both sodium magnetic resonance (MR) and T1rho relaxation mapping aimed at measuring molecular changes in cartilage for the diagnostic imaging of osteoarthritis are reviewed. First, an introduction to structure of cartilage, its degeneration in osteoarthritis (OA) and an outline of diagnostic imaging methods in quantifying molecular changes and early diagnostic aspects of cartilage degeneration are described. The sodium MRI section begins with a brief overview of the theory of sodium NMR of biological tissues and is followed by a section on multiple quantum filters that can be used to quantify both bi-exponential relaxation and residual quadrupolar interaction. Specifically, (i) the rationale behind the use of sodium MRI in quantifying proteoglycan (PG) changes, (ii) validation studies using biochemical assays, (iii) studies on human OA specimens, (iv) results on animal models and (v) clinical imaging protocols are reviewed. Results demonstrating the feasibility of quantifying PG in OA patients and comparison with that in healthy subjects are also presented. The section concludes with the discussion of advantages and potential issues with sodium MRI and the impact of new technological advancements (e.g. ultra-high field scanners and parallel imaging methods). In the theory section on T1rho, a brief description of (i) principles of measuring T1rho relaxation, (ii) pulse sequences for computing T1rho relaxation maps, (iii) issues regarding radio frequency power deposition, (iv) mechanisms that contribute to T1rho in biological tissues and (v) effects of exchange and dipolar interaction on T1rho dispersion are discussed. Correlation of T1rho relaxation rate with macromolecular content and biomechanical properties in cartilage specimens subjected to trypsin and cytokine-induced glycosaminoglycan depletion and validation against biochemical assay and histopathology are presented. Experimental T1rho data from osteoarthritic specimens, animal models, healthy human subjects and as well from osteoarthritic patients are provided. The current status of T1rho relaxation mapping of cartilage and future directions is also discussed.

Muskuloskeletal MR imaging at 3.0 T: current status and future perspectives

Magnetic resonance (MR) imaging has become an important diagnostic tool in evaluation of the musculoskeletal system. While most examinations are currently performed at magnetic field strengths of 1.5 T or lower, whole-body MR systems operating at 3.0 T have recently become available for clinical use. The higher field strengths promise various benefits, including increased signal-to-noise ratios, enhanced T2* contrast, increased chemical shift resolution, and most likely a better diagnostic performance in various applications. However, the changed T1, T2, and T2* relaxation times, the increased resonance-frequency differences caused by susceptibility and chemical-shift differences, and the increased absorption of radiofrequency (RF) energy by the tissues pose new challenges and/or offer new opportunities for imaging at 3.0 T compared to 1.5 T. Some of these issues have been successfully addressed only in the very recent past. This review discusses technical aspects of 3.0 T imaging as far as they have an impact on clinical routine. An overview of the current data is presented, with a focus on areas where 3.0 T promises equivalent or improved performance compared 1.5 T or lower field strengths.

Nonarthroplasty treatment of glenohumeral cartilage lesions

Treatment of young, active persons with symptomatic cartilage lesions of the glenohumeral joint represents a significant challenge. Diagnosis of glenohumeral chondral defects is not always straightforward and effective treatment requires familiarity with a number of techniques. Low-demand individuals may accept palliative therapy in the form of arthroscopic debridement as a temporizing solution. However, younger, high-demand individuals require a careful, stepwise approach that includes reparative, restorative, and reconstructive strategies. Reparative strategies use marrow-stimulation techniques to induce formation of fibrocartilage. Restorative tactics attempt to replace damaged cartilage with hyaline or hyaline-like tissue using osteochondral or chondrocyte transplantation. Large lesions that are not candidates for reparative or restorative procedures can be approached using reconstruction methods such as biologic resurfacing. This review examines causes of chondral injury in the glenohumeral joint, discusses diagnostic strategies, and presents a practical framework including palliative, reparative, restorative, and reconstructive options with which one can formulate a treatment plan for these patients.