Development of a Pressure-Sensitive Conductive Rubber Sensor for Analyzing Meniscal Injury in Porcine Models

The assessment of the distribution of contact pressure on the meniscus is important in the elucidation of kinematics, etiology of joint diseases, and establishment of treatment methods. Compared with sensors widely used in recent years, pressure-sensitive conductive rubber sensors are easy to mold, flexible, durable, and resistant to shearing forces. This study is aimed at developing a rubber sensor for meniscal research and evaluating the pressure distribution after meniscal injury using porcine models. After confirming the reliability of the rubber sensor, contact pressure was obtained from the rubber sensor using the medial meniscus and femur of the porcine knee. Three test conditions of intact meniscus, radial tear, and meniscectomy were prepared, and a compressive load of 100 N was applied. After confirming the high reliability of the rubber sensor, the intact meniscus had the most uniform pressure distribution map, while the pressure in the meniscectomy model was concentrated in the resection region. The high-pressure region was significantly smaller in the intact group than in the radial tear models after 80 and 100 N ( P < 0.05 ). The rubber sensor captured the pressure concentration specific to each examination group and was useful for evaluating the relationship between the pattern of meniscal injury and changes in the biomechanical condition of the knee.

Modified capsulorhexis for fluid-filled mature cataracts

Background: The aim of this study was to develop a modified capsulorhexis technique featuring a new maneuver for the removal of subcortical fluid in fluid-filled mature cataracts to avoid high intralenticular pressure. Methods: This prospective interventional study included 33 eyes with mature cataracts and evidence of subcapsular fluid spaces by slit lamp examination. For each patient, 20% mannitol was administered intravenously according to the bodyweight 1 h preoperatively. Under peribulbar anesthesia, a 2.2-mm main incision was made, and the anterior chamber was filled with a dispersive ophthalmic viscosurgical device. Using a bent-tip cystotome, a 2-mm curved incision was made in the center of the anterior capsule, which released subcortical fluid and was drained through compression of the posterior lip of the main incision using a spatula. Then, fine gentle milking in all quadrants around the puncture on the anterior lens capsule from the periphery toward the site of puncture using the blunt-edged spatula further assists drainage of subcortical fluid and breaks fine septa inside the lens to remove fluid from intralenticular fluid pocket collections. Results: The study included 15 (45.5%) men and 18 (54.5%) women with a mean ± standard deviation (SD) of age of 63.2 ± 5.33 and 64.4 ± 6.21 years, respectively. The modified capsulorhexis technique was performed for 33 intumescent cataracts. Capsulorhexis was completed in all cases; capsulorhexis was easy in 31 (94%) eyes and difficult in 2 (6%) eyes. In the two difficult cases, radial extension occurred in one eye, and it was retrieved using the Little technique; the other case with radial tear was completed successfully using a retinal micro scissor from the other edge of the capsulorhexis until reaching an oval, continuous capsulorhexis. Conclusions: This modified capsulorhexis technique with compression on the posterior lip of the main incision and capsule milking allowed for a safe, continuous curvilinear capsulorhexis. Further comparative studies are necessary to confirm our preliminary results. How to cite this article: Ghoneim EM. Modified capsulorhexis for fluid-filled mature cataracts. Med Hypothesis Discov Innov Ophthalmol. 2021 Summer; 10(2): 17-24. https://doi.org/10.51329/mehdioptometry1422

Repair of a Complete Radial Tear of the Lateral Meniscus

Background: Recognizing and repairing a lateral meniscus complete radial tear is critical, as this tear pattern makes the meniscus nonfunctional for load sharing of axial forces, and the convex shape of the lateral tibial plateau increases contact pressure. Indications: The diagnosis of a lateral meniscus complete radial tear was supported by joint effusion, lateral joint line tenderness, positive McMurray test, and magnetic resonance imaging findings. Arthroscopy confirmed the complete radial tear. Technique Description: During the procedure, a self-capturing suture passer was used to pass a size 0 high-strength suture through the meniscus. To start the repair, the free ends of the suture were passed from top to bottom on both sides of the tear. These free ends were then crossed on the bottom of the meniscus to create an X configuration and passed from the bottom to top slightly further back from the first suture passes. A spinal needle and a chia were used from outside-in to create a side-to-side suture across the tear to reinforce the repair, and a knot was then tied on the outer capsule. The chia was used once again to shuttle the size 0 sutures to the exterior portion of the knee and the knots were tied on top of the capsule. Results: Postoperatively, patients are 25% weightbearing with a 0° to 90° range of motion restriction for 6 weeks, with no deep squatting for 3 months. With an isolated radial tear repair, the patient can expect to return to sport by 5 months. Radial tear repair outcomes demonstrate reduced lateral meniscus extrusion, complete meniscus healing in 86.4% of patients, and significantly improved International Knee Documentation Committee, Lysholm, and Tegner scores. Discussion/Conclusion: Repairing a complete radial tear of the lateral meniscus restores the function of the meniscus. This surgical technique provides a high rate of complete meniscus healing and excellent patient satisfaction.

Capsulorhexis Under Continuous Fluid Pressure in Intumescent Cataracts: A New Technique

Purpose: To evaluate the effectiveness of the anterior capsulorhexis technique under continuous fluid pressure with anterior chamber maintainer in intumescent cataracts.Methods: Scheduled for phacoemulsification due to intumescent cataracts, 84 eyes of 84 patients were included in the study. An anterior chamber maintainer, which provided continuous fluid pressure in the anterior chamber, was placed in the patients of Group 1 (n = 42). Capsulorhexis without viscoelastic was then applied under continuous fluid pressure. In Group 2 (n = 42) patients, capsulorhexis was performed by utilizing an ophthalmic viscoelastic device (OVD) to the anterior chamber. The efficiency and reliability of our capsulorhexis method were evaluated by comparing the intraoperative and postoperative complications that occurred in such cases.Results: Radial tear did not occur in any of the cases in the capsulorhexis stage in Group 1; however, 6 Group 2 patients were observed to have radial tears(p<0.05). Progression of the anterior capsule, which did not turn into a radial tear, to the periphery was observed in 2 patients in Group 1, and 8 patients in Group 2(p<0.05). When liquefied cortical material egress dynamics were evaluated; the controlled fluid output was observed in 41 patients (97.61%) in Group 1, and 29 patients (69.4%) in Group 2 (p<0.001). There was no statistically significant difference revealed between the two groups in the endothelial cell loss (p> 0.05).Conclusion: The technique we used provides a controlled and safe capsulorhexis in intumescent cataracts, reduces surgical complications, and does not require any additional cost.

Risk Factors for Rapid Chondrolysis After Partial Lateral Meniscectomy: A Scoping Review of the Literature

Background: The occurrence of rapid chondrolysis after partial lateral meniscectomy is rare. The pathophysiology, risk factors, and outcomes of treatment have not been established. Purpose: The primary aim of this study was to perform a scoping review of the literature to determine the potential risk factors and pathogenesis of rapid chondrolysis. The secondary objective was to report outcomes of treatment. Study Design: Systematic (scoping) review. Methods: A scoping review of the literature was conducted in accordance with the framework of Arksey and O’Malley. A search strategy based on the terms “chondrolysis” AND “knee,” “chondrolysis” AND “meniscus,” and “chondral damage” AND “lateral meniscus” was applied to the PubMed database on March 31, 2020. All relevant studies were included. Patient demographics and clinical data were extracted from these studies and analyzed in order to investigate the potential risk factors, pathogenesis, and outcomes of treatment for rapid chondrolysis. Results: Five articles (22 cases) featuring rapid chondrolysis in the lateral compartment after partial lateral meniscectomy were identified and included. The condition occurred most frequently in patients who were young (mean age, 25.6 years), male (20/22 cases; 91%), and participating in high-intensity sports (19/22 cases; 86.4%) within 1 year of the index procedure. Half of the included study population underwent surgery for a radial tear. All professional athletes (13/13) returned to the preinjury level of sport. All authors of included studies suggested that the main causal risk factor was mechanical focal cartilage overload in the lateral compartment of the knee. Conclusion: Rapid chondrolysis after partial lateral meniscectomy is a rare condition that typically occurs within 12 months of the index procedure. Younger age, male sex, high-intensity sports participation, and some meniscal tear patterns (eg, radial tear) are potentially important risk factors. Return-to-sport rates at short-term follow up are high, but no long-term studies were identified. The pathogenesis of rapid chondrolysis seems to relate to mechanical focal cartilage overload.

Lateral meniscal allograft transplantation and stabilisation in a dog with stifle subluxation

This case describes the clinical features and the favourable clinical outcome after a lateral meniscal allograft transplant and stifle stabilisation in a dog that suffered a significant injury to its stifle, which included irreparable injury to the lateral meniscus, cranial cruciate ligament rupture and medial collateral rupture. The lateral meniscus was extensively damaged having avulsed from its peripheral attachments and with a radial tear across 70 per cent of its mid-body. After four years, the owners reported that the dog continued with an active lifestyle and only occasionally required non-steroidal anti-inflammatory analgesics for sporadic episodes of mild lameness after vigorous exercise.

Radial Meniscal Tears Are Best Repaired by a Modified “Cross” Tie-Grip Suture Based on a Biomechanical Comparison of 4 Repair Techniques in a Porcine Model

Background: The tie-grip suture can fix radial tears more rigidly than simple conventional sutures. However, one shortcoming is the residual gap at the central margin of the tear. The tie-grip suture was modified to address this issue and named the “cross tie-grip suture.” Purpose/Hypothesis: The purpose of this study was to compare the suture stability and strength among 4 suturing techniques: the original tie-grip, cross tie-grip, and 2 conventional sutures (double horizontal and cross). It was hypothesized that the cross tie-grip suture would show the least displacement and resist the greatest maximum load. Study Design: Controlled laboratory study. Methods: A total of 40 fresh-frozen porcine knees were dissected to acquire 80 menisci; 20 menisci were tested in each suture group. A radial tear was created at the middle third of the meniscal body. Repair was performed with the following: original tie-grip, cross tie-grip, double horizontal, and cross sutures. The mechanical strength of sutured menisci was evaluated using a tensile testing machine. All menisci underwent submaximal loading and load to failure. The gap distance and ultimate failure load were compared using analysis of variance. The failure mode was recorded after load-to-failure testing. Results: Displacement after 500 cycles was significantly smaller in the cross tie-grip group (0.4 ± 0.3 mm) compared with the tie-grip (0.9 ± 0.6 mm), double horizontal (1.2 ± 0.7 mm), and cross suture groups (1.4 ± 0.6 mm) ( P < .05). The ultimate failure load was significantly greater in the cross tie-grip (154.9 ± 29.0 N) and tie-grip (145.2 ± 39.1 N) groups compared with the double horizontal (81.2 ± 19.9 N) and cross suture groups (87.3 ± 17.7 N) ( P < .05). Tissue failure was the most common mode of failure in all groups. Conclusion: Upon repair of radial meniscal tears, the cross tie-grip suture showed less displacement compared with that of the tie-grip, double horizontal, and cross sutures and demonstrated equivalent load to failure to that of the tie-grip suture at time zero. Clinical Relevance: The cross tie-grip suture provided high resistance to displacement after repair of radial tears and may be advantageous in healing for radial meniscal tears.