Diagnostic accuracy in rotator cuff tears: clinical tests vs MRI

Background: Till date there is a lack of consensus regarding validity of clinical tests in identifying the rotator cuff injuries and also the predictive value of noninvasive investigations done to confirm such shoulder pathology.Methods: We included 48 patients with shoulder complaints in our study who underwent blinded clinical examination and MRI of shoulder, whose findings were compared with arthroscopic findings and were statistically analyzed.Results: In the study group mean age was 47 years and 71% were males. When compared with arthroscopy, clinical examination for supraspinatus had better sensitivity (90) but low specificity and negative predictive value (NPV) (37.5). MRI evaluation of supraspinatus had specificity of 85 and NPV of 60. Infraspinatus had almost similar statistical values. MRI was found to have better specificity (89.5) in comparison with clinical examination (52.6) in subscapularis evaluation along with higher positive (67 vs. 30) and negative predictive value (94 vs. 90).Conclusions: Clinical examination is good in identifying lesion or tear of supraspinatus and subscapularis but may also have false positives, where usage of noninvasive MRI will reduce these false positive in comparison with gold standard arthroscopy. Although clinical examination is very useful for diagnosis of rotator cuff injuries, MRI could be used to improve specificity and predictive values in patients who are planned for surgical management of rotator cuff injury

Preoperative estimation of humerus intramedullary nail length using clinical landmarks

Purpose: Intramedullary interlocking nailing is one of the accepted methods of treating humerus diaphyseal fractures. Appropriate nail length and diameter are of paramount importance to achieve a stable fracture fixation. Estimating the nail length can be as challenging in certain cases as it is important. This study aims to provide an easy-to-use formula utilizing clinical measurements from contra lateral arm to accurately estimate humeral nail length. Methods: This descriptive cross-sectional study was conducted at 3 tertiary care hospitals in Mangalore, India. Patients above the age of 18 years coming to the outpatient department with elbow, shoulder or arm complaints requiring radiological investigation from July 2021 to July 2022 were included. Patients with fractures or dislocations of upper limbs, malunited or non-united fractures of upper limbs, congenital or developmental deformities and patients with open growth plates were excluded. Patients’ variables (like age and gender), radiological humerus length and contralateral arm clinical measurements were recorded. An independent samples t-test was used for univariate analysis, and linear regression analysis was done to estimate the desired nail length using the clinical measurement of the humerus (cm) in both genders separately. The significance level was set at p < 0.05. Results: Our study included 204 participants of which 108 were male and 96 were female. The formula for predicting humeral nail length in males is (−2.029) + (0.883 × clinical measurement). The formula for females is 1.862 + (0.741 × clinical measurement). A simplified formula to determine humeral nail length is 0.9 clinical length – 2 cm (in males) and 0.7 × clinical length + 2 cm (in females). Conclusion: To improve the stability of fixation with intramedullary nails it is imperative to select the appropriate nail length. There have been studies that devised reliable methods of determining nail lengths in the tibia and femur using preoperative clinical measurements. A similar clinical method of determining humeral nail length is lacking in the literature. Our study was able to correlate radiological lengths of the humerus medullary canal with clinical measurements performed using anatomical landmarks to arrive at a formula. This allows for a reliable and easy nail length determination preoperatively

Wear estimation at the contact surfaces of oval shaped hip implants using finite element analysis

AbstractThe hip joint is one of the most essential joints for transmitting weights to the lower abdomen during day-to-day activities. Loosening of hip implants is mostly caused by wear. The wear assessment during the design stage offers a clear sense of the implant’s life expectancy, and modest adjustments in the design may also greatly enhance the implant’s life expectancy, lowering the probability of revision surgery. Linear wear is estimated at the contact surfaces of the femoral head to the acetabular cup and the acetabular cup to the backing cup in this study. In this work, oval-shaped hip implant is considered with a femoral head diameter of 28 mm, an acetabular cup thickness of 4 mm, and a backing cup thickness of 2 mm. The Archard’s law used to estimate the linear wear rate. It is observed that when the acetabular cup is made of UHWMPE and the stem, femoral head, and backing cup are made of CoCr, the least overall deformation is 0.394 mm during walking loads. When the stem is considered Ti−6Al−4 V and the acetabular cup of UHWMPE, the minimum wear between the femoral head and acetabular cup is 0.063 mm/year. During a typical standing posture, an acetabular cup-to-backing cup wear rate of 0.007 mm/year is estimated. Overall, the CoCr material combination had the lowest wear rate in the four activities considered for this work. These implants designs can be 3D-printed and further can be tested in a hip simulator under the same loading conditions