Dynamic contact area ratio in shoulder instability: an innovative diagnostic technique measuring interplay of bony lesions.

PURPOSE: The hypothesis of this study is that Dynamic Contact Area Ratio of the humerus and glenoid, measured with CT scans, is significantly reduced in patients with anterior shoulder instability compared to the Dynamic Contact Area Ratio in a control group of people without shoulder instability. METHODS: Preoperative CT scans of patients who underwent surgery for anterior shoulder instability were collected. Additionally, the radiologic database was searched for control subjects. Using a validated software tool (Articulis) the CT scans were converted into 3-dimensional models and the amount the joint contact surface during simulated motion was calculated. RESULTS: CT scans of 18 patients and 21 controls were available. The mean Dynamic Contact Area Ratio of patients was 25.2 ± 6.7 compared to 30.1 ± 5.1 in healthy subjects (p = 0.014). CONCLUSION: Dynamic Contact Area Ratio was significantly lower in patients with anterior shoulder instability compared to controls, confirming the hypothesis of the study. The findings of this study indicate that calculating the Dynamic Contact Area Ratio based on CT scan images may help surgeons in diagnosing anterior shoulder instability. LEVEL OF EVIDENCE: III.

International survey and surgeon's preferences in diagnostic work-up towards treatment of anterior shoulder instability.

PURPOSE: Recurrent anterior shoulder instability after surgical treatment can be caused by bony defects. Several diagnostic tools have been designed to measure the extent of these bony lesions. Currently, there is no consensus which measurement tool to use and decide which type of surgery is most appropriate. We therefore performed an evaluation of agreement in surgeons' preference of diagnostic work-up and surgical treatment of anterior shoulder instability. METHODS: An international survey was conducted amongst orthopaedic shoulder surgeons. The survey contained questions about surgeons' experience, clinical and radiological examination and the subsequent treatment for anterior shoulder instability. Descriptive statistics were used to present the data, and percentages of responding surgeons were calculated. RESULTS: The questionnaire was completed by 197 delegates from 46 countries. 55 % of the respondents think evidence in current literature is sufficient on diagnostic work-up for anterior shoulder instability. Anamnestic, number of dislocations was most frequently asked (by 95 % of respondents), the most frequently used test is the apprehension test (91 %). For imaging, conventional X-ray in various directions was most performed, followed by MR arthrography and plane CT scan respectively. The responding surgeons perform surgery (labrum repair or Latarjet) in 51 % of the patients. A median of 25 % glenoid bone loss was given by the respondents, as cut-off from when to perform a bony repair. CONCLUSION: Many different diagnostic examinations for assessing shoulder instability are used and a high variety is seen in the use of diagnostic tools. Also no consensus is seen in the use of different surgical options (arthroscopic and open procedures). This implies the need for more research on diagnostic imaging and the correlation with specific subsequent surgical treatment. LEVEL OF EVIDENCE: Survey, level of evidence IV.

[Femoroacetabular impingement: frequently missed in patients with chronic groin pain]. / Femoro-acetabulaire impingement: vaak gemist bij chronische liesklachten.

Femoroacetabular impingement is a diagnosis that is often missed in patients with chronic groin pain. The condition often appears in young athletes. An anatomic deformity of the femoral head and the acetabular ridge causes an impingement that damages the subchondral tissue. This damage can result in sharp pain in the groin during specific hip movements and the acetabular labrum may also be ruptured. Diagnosing femoroacetabular impingement and a labral tear can be a challenge. We present the case of a 19-year-old male who twisted his right hip joint during a game of football. Physiotherapy only aggravated the pain. Further diagnostics showed femoroacetabular impingement and a labral tear. Arthroscopic intervention in the hip joint by an orthopedic surgeon lead to immediate pain relief, and two years after surgery the patient is still free of pain and has returned playing sport at his previous level. Femoroacetabular impingement can be a cause of chronic groin pain in young athletes. Hip arthroscopy is a safe and effective treatment, enabling the patient to return to playing sport at their previous level.

Range of motion implications of proximal humerus fractures: a case study.

BACKGROUND: Functional outcome in surgical treatment of Neer three- and four-part proximal humerus fractures (PHF) varies greatly and depends on multiple parameters. Important parameters are the amount and direction of displacement and the necessary reduction of fragments during surgery. These are patient-specific parameters and are difficult to determine using traditional modalities such as radiographs and computed tomography (CT). METHODS: A 58-year-old female patient was reported in the emergency department with a three-part PHF. CT scan images showed that the humeral shaft was medialised and internally rotated, but with a marginally displaced greater tuberosity fragment. Using a bone-determined range of motion (ROM) simulation system, we analysed the CT scan and calculated the required correction needed to prevent post-operative impingement. The fracture was reduced and stabilised by a locking plate, realigning the medialised and internally rotated humeral shaft. The post-operative bone-determined ROM was determined using a post-operative CT scan and the motion simulation system. RESULTS: ROM limitations due to bony impingement visible in the simulations of the pre-operative CT scan had mostly disappeared in the simulations of the post-operative CT scan. Twelve weeks post-surgery the patient has regained close to 80% of her ROM. CONCLUSIONS: This case demonstrates the applicability of a new diagnostic tool that can be used to identify bony impingement and helps in making the decision for conservative or surgical treatment of a PHF. The simulation of post-trauma function was indicative of functional outcome. This supports our claim that the system may be used to facilitate the treatment decision regarding PHF.

Femoroacetabular impingement and its implications on range of motion: a case report.

INTRODUCTION: Femoroacetabular impingement leads to limited hip motion, pain and progressive damage to the labrum. Assessment of the amount and location of excessive ossification can be difficult, and removal does not always lead to pain relief and an increase of function. One of the challenges ahead is to discover why certain cases have poor outcomes. CASE PRESENTATION: The technical and clinical results of two consecutive arthroscopic shavings of an osseous cam protrusion are described in our patient, a 50-year-old Caucasian man with complaints of femoroacetabular impingement. At 12 weeks after the first arthroscopic shaving, our patient still experienced pain. Using a range of motion simulation system based on computed tomography images the kinematics of his hip joint were analyzed. Bone that limited range of motion was removed in a second arthroscopic procedure. At six months post-operatively our patient is almost pain free and has regained a range of motion to a functional level. CONCLUSION: This case demonstrates the relevance of range of motion simulation when the outcome of primary arthroscopic management is unsatisfactory. Such simulations may aid clinicians in determining the gain of a second operation. This claim is supported by the correlation of the simulations with clinical outcome, as shown in this case report.

Combined surface and volume processing for fused joint segmentation.

PURPOSE: Segmentation of rheumatoid joints from CT images is a complicated task. The pathological state of the joint results in a non-uniform density of the bone tissue, with holes and irregularities complicating the segmentation process. For the specific case of the shoulder joint, existing segmentation techniques often fail and lead to poor results. This paper describes a novel method for the segmentation of these joints. METHODS: Given a rough surface model of the shoulder, a loop that encircles the joint is extracted by calculating the minimum curvature of the surface model. The intersection points of this loop with the separate CT-slices are connected by means of a path search algorithm. Inaccurate sections are corrected by iteratively applying a Hough transform to the segmentation result. RESULTS: As a qualitative measure we calculated the Dice coefficient and Hausdorff distances of the automatic segmentations and expert manual segmentations of CT-scans of ten severely deteriorated shoulder joints. For the humerus and scapula the median Dice coefficient was 98.9% with an interquartile range (IQR) of 95.8-99.4 and 98.5% (IQR 98.3-99.2%), respectively. The median Hausdorff distances were 3.06 mm (IQR 2.30-4.14) and 3.92 mm (IQR 1.96 -5.92 mm), respectively. CONCLUSION: The routine satisfies the criterion of our particular application to accurately segment the shoulder joint in under 2 min. We conclude that combining surface curvature, limited user interaction and iterative refinement via a Hough transform forms a satisfactory approach for the segmentation of severely damaged arthritic shoulder joints.