The finite element method (FEM) represents a computer simulation method, originally used in civil engineering, which dates back to the early 1940s. Applications of FEM have also been used in numerous medical areas and in orthopedic surgery. Computing technology has improved over the years and as a result, more complex problems, such as those involving the spine, can be analyzed. The spine is a complex anatomical structure that maintains the erect posture and supports considerable loads. Applications of FEM in the spine have contributed to the understanding of bone biomechanics, both in healthy and abnormal conditions, such as scoliosis, fractures (trauma), degenerative disc disease and osteoporosis. However, since FEM is only a digital simulation of the real condition, it will never exactly simulate in vivo results. In particular, when it concerns biomechanics, there are many features that are difficult to represent in a FEM. More FEM studies and spine research are required in order to examine interpersonal spine stiffness, young spine biomechanics and model accuracy. In the future, patient-specific models will be used for better patient evaluations as well as for better pre- and inter-operative planning.

The Achilles tendon represents the most commonly ruptured tendon of the human body. Numerous studies have evaluated, throughout the years, management options regarding acute Achilles tendon rupture. Minimally invasive techniques have recently gained more popularity. Endoscopic flexor hallucis longus tendon transfer has been mainly described as a treatment method for neglected Achilles tendon ruptures. However, it has recently been described as an applicable treatment option for acute Achilles tendon ruptures as well. Nevertheless, this procedure is technically quite demanding and should be performed by experienced surgeons. This technical note thoroughly describes the endoscopic flexor hallucis longus transfer technique for acute Achilles tendon ruptures, focusing on the most important technical aspects, thus attempting to simplify and render this procedure more widely accepted. Technique Video: video See video under supplementary data.

Background: Here, we introduce a comprehensive treatment algorithm for posterolateral rotatory instability (PLRI) of the elbow, a condition affecting elbow mobility. We outline a diagnostic approach and a novel surgical management plan through the arthroscopic surgeon’s point of view. Methods: The central focus of this management approach is the integrity of common extensor origin (CEO). High clinical suspicion must be evident to diagnose PLRI. Special clinical and imaging tests can confirm PLRI but sometimes the final confirmation is established during the arthroscopic treatment. The most appropriate treatment is determined by the degree of CEO integrity. Results: The treatment strategy varies with the CEO’s condition: intact or minor tears require arthroscopic lateral collateral ligament imbrication, while extensive tears may need plication reinforced with imbrication or, in cases of retraction, a triceps tendon autograft reconstruction of the lateral ulnar collateral ligament alongside CEO repair. These approaches aim to manage residual instability and are complemented using a tailored rehabilitation protocol to optimize functional outcomes. Conclusion: PLRI is a unique clinical condition and should be treated likewise. This algorithm offers valuable insights for diagnosing and treating PLRI, enhancing therapeutic decision-making.

Posterolateral rotatory instability (PLRI) of the elbow is commonly treated with open lateral collateral ligament (LCL) reconstruction techniques. This cohort study evaluates the efficacy of a less invasive arthroscopic LCL imbrication technique for reducing grade I or II PLRI. Forty-three patients with stage 1 or 2 PLRI, unresponsive to conservative therapy, were included. Diagnoses were based on chronic post-traumatic pain (11 patients), chronic atraumatic lateral elbow pain (20), and previous open tennis elbow surgery (12). Following clinical and arthroscopic diagnosis confirmation, the LCL imbrication technique was performed. The Mayo Elbow Performance Score and range of motion (ROM) were assessed preoperatively and postoperatively using the Shapiro-Wilk test and Wilcoxon signed rank test, respectively, with a minimum 12-month follow-up (range 12-48 months). The Mayo Elbow Performance Score increased significantly from a median of 45 points preoperatively to 90 (range 80-100) at 3 months and 95 (range 80-100) at 12 months follow-up (P < .001). Postoperative median flexion reached 140°, and extension was 0°. At 12 months, 2 patients experienced a 10° extension deficit; 95.3% (41 of 43) achieved full ROM. Knot irritation occurred in 4 patients (out of the first 10 of this cohort, 9.3%), 3 of them requiring knot removal. Switching to a polydioxanone 1 suture eliminated this complication. One patient underwent arthroscopic arthrolysis for adhesions after 14 months. Arthroscopic LCL imbrication offers favorable outcomes for grade I or II PLRI from the third postoperative month with minimal complications. A slight restriction in ROM and transient knot discomfort were the main issues, the latter resolved by switching to a thinner polydioxanone suture.

Acute Achilles tendon rupture (AATR) in patients with multimorbidity poses a significant therapeutic challenge to surgeons because of the increased risk for wound-healing-related complications. Thus, nonoperative management has been these individuals' most widely adopted treatment. We report a case of a 66-year-old patient with AATR who was treated with endoscopic flexor hallucis longus (FHL) transfer. His medical history was remarkable for recent stroke, hypertension, prediabetes, pemphigus under oral methylprednisolone, smoking, and recent pneumonia. The patient was evaluated up to two years postoperatively and was satisfied with the outcome since he was able to maintain his pre-traumatic activity level. No complications were noted. The Achilles tendon total rupture score was 92 out of a maximum of 100. This favorable outcome indicates that endoscopic FHL transfer may be a safe alternative treatment option for patients with an increased risk of surgical complications.