Open versus arthroscopic release for lateral patellar compression syndrome: a randomized-controlled trial

Strain evaluation of axially loaded collateral ligaments: a comparison of digital image correlation and strain gauges

The response of soft tissue to loading can be obtained by strain assessment. Typically, strain can be measured using electrical resistance with strain gauges (SG), or optical sensors based on the digital image correlation (DIC), among others. These sensor systems are already established in other areas of technology. However, sensors have a limited range of applications in medical technology due to various challenges in handling human soft materials. The aim of this study was to compare directly attached foil-type SG and 3D-DIC to determine the strain of axially loaded human ligament structures. Therefore, the medial (MCL) and lateral (LCL) collateral ligaments of 18 human knee joints underwent cyclic displacement-controlled loading at a rate of 20 mm/min in two test trials. In the first trial, strain was recorded with the 3D-DIC system and the reference strain of the testing machine. In the second trial, strain was additionally measured with a directly attached SG. The results of the strain measurement with the 3D-DIC system did not differ significantly from the reference strain in the first trial. The strains assessed in the second trial between reference and SG, as well as between reference and 3D-DIC showed significant differences. This suggests that using an optical system based on the DIC with a given unrestricted view is an effective method to measure the superficial strain of human ligaments. In contrast, directly attached SGs provide only qualitative comparable results. Therefore, their scope on human ligaments is limited to the evaluation of changes under different conditions.

Does drainage affect development of heterotopic ossification after total hip arthroplasty?

OBJECTIVE

To investigate the effect of drainage on heterotopic ossification (HO) after total hip arthroplasty (THA) and to evaluate other postoperative complications and joint dysfunction between patients with and without drainage.

METHODS

In this retrospective cohort study, the medical records of patients who underwent THA from 2017 to 2019 were reviewed. The patients were divided into a drainage group and non-drainage group. Standard preoperative anteroposterior and lateral radiographs were assessed by senior radiologists for HO analysis. Clinical indicators included the hemoglobin concentration, superficial infection, blood transfusion, hematoma formation, hip range of motion (ROM), erythrocyte sedimentation rate, C-reactive protein concentration, dressing changes, visual analogue scale score, and Harris Hip Score (HHS).

RESULTS

The incidence of HO was significantly higher in the drainage than non-drainage group (32.0% vs. 16.3%). The presence of severe HO (Brooker grade III or IV) was also different between the groups. Patients in the non-drainage group had smaller ROM early after surgery, but the final ROM and HHS did not differ significantly between the groups.

CONCLUSIONS

The rate and degree of HO after THA were significantly different between patients with and without drainage. There is no added advantage of closed suction drainage over no drainage in primary THA.

Editorial Commentary: Handling the (Contact) Pressure in Patellofemoral Surgery: The Role of Lateral Retinacular Release

The role of lateral retinacular release for the treatment of patellofemoral pathology has evolved over the years. Although once popularized in the treatment of patellofemoral pain and instability, complications such as iatrogenic medial patellar instability and decreases in lateral patellar stability have limited the indications for performing isolated lateral release. However, there exists a need for more clearly defined parameters and understanding of when and how lateral release should be incorporated with other procedures during patellar stabilization and joint-preservation surgery. Advances in finite element analysis, as well as refining our surgical indications and techniques for concurrent lateral release, will allow us to optimize both joint pressures and stability during the surgical management of patellar instability.

The Lateral Side: When and How to Release, Lengthen, and Reconstruct

The lateral patellofemoral complex is an important stabilizer to medial and lateral displacement of the patella. Soft tissue abnormalities can range from pathologic tightness to laxity, presenting with symptoms related to patellar instability, anterior knee pain, or arthritis. Clinical evaluation should be performed to confirm patellar dislocation, assess the integrity of the lateral and medial soft tissues, and explore other pathoanatomic factors that may need to be addressed. Lateral retinacular lengthening is recommended over lateral release owing to the potential of iatrogenic medial instability with release, and a lateral patellofemoral ligament reconstruction can be performed to effectively treat medial instability.