Effects of ligament repair on laxity and creep behavior of an early healing ligament scar

The novel epiligament theory: differences in healing failure between the medial collateral and anterior cruciate ligaments

According to current literature, 90% of knee ligament injuries involve the medial collateral ligament or the anterior cruciate ligament. In contrast to the medial collateral ligament, which regenerates relatively well, the anterior cruciate ligament demonstrates compromised healing. In the past, there were numerous studies in animal models that examined the healing process of these ligaments, and different explanations were established. Although the healing of these ligaments has been largely investigated and different theories exist, unanswered questions persist.

Therefore, the aim of this article is 1) to review the different historical aspects of healing of the medial collateral ligament and present the theories for healing failure of the anterior cruciate ligament; 2) to examine the novel epiligament theory explaining the medial collateral ligament healing process and failure of anterior cruciate ligament healing; and 3) to discuss why the enveloping tissue microstructure of the aforementioned ligaments needs to be examined in future studies.

We believe that knowledge of the novel epiligament theory will lead to a better understanding of the normal healing process for implementing optimal treatments, as well as a more holistic explanation for anterior cruciate ligament healing failure.

Anatomic ligament consolidation of the superior acromioclavicular ligament and the coracoclavicular ligament complex after acute arthroscopically assisted double coracoclavicular bundle stabilization

PURPOSE

The consolidation of the acromioclavicular (AC) and coracoclavicular (CC) ligament complex after arthroscopically assisted stabilization of acute acromioclavicular joint (ACJ) separation is still under consideration.

METHODS

Fifty-five consecutive patients after arthroscopically assisted double-CC-bundle stabilization within 14 days after acute high-grade ACJ separation were studied prospectively. All patients were clinically analysed preoperatively (FU0) and post-operatively (FU1 = 6 months; FU2 = 12 months). The structural MRI assessments were performed at FU0 (injured ACJ) and at FU2 bilateral (radiologic control group) and assessed separately the ligament thickness and length at defined regions for the conoid, trapezoid and the superior AC ligament.

RESULTS

Thirty-seven patients were assessed after 6.5 months and after 16.0 months. The 16-month MRI analysis revealed for all patients continuous ligament healing for the CC-complex and the superior AC ligament with in the average hypertrophic consolidation compared to the control side. Separate conoid and trapezoid strands (double-strand configuration) were detected in 27 of 37 (73%) patients, and a single-strand configuration was detected in 10 of 37 (27%) patients; both configurations showed similar CCD data. The ligament healing was not influenced by the point of surgery, age at surgery and heterotopic ossification. The clinical outcome was increased (FU0-FU2): Rowe, 47.7-97.0 pts.; TAFT, 3.9-10.6 pts.; NAS _pain, 8.9-1.4 pts. (all P < 0.05).

CONCLUSION

The arthroscopically assisted double-CC-bundle stabilization within 14 days after acute high-grade ACJ separation showed 16 months after surgery sufficient consolidations of the AC and double-CC ligament complex in 73%.

LEVEL OF EVIDENCE

III, Case series.

Comparison between Operative and Non-Operative Treatment of the Medial Collateral Ligament: Histological and Ultrastructural Findings during Early Healing in the Epiligament Tissue in a Rat Knee Model

The medial collateral ligament of the knee joint is one of the most commonly injured ligaments of the knee. Recent data have shown that the thin layer of connective tissue covering the ligament, known as the epiligament, is essential for its nutrition and normal function, as well as its healing after injury. The aim of the present study was to investigate and compare the changes in the epiligament of the medial collateral ligament which occurred during operative and non-operative treatment throughout the first month after injury. We used 27 male Wistar rats randomly allocated to three groups. In the 9 rats belonging to the first group, the medial collateral ligament was fully transected and left to heal spontaneously without suture. In the 9 rats belonging to the second group, the transected ends were marked with a 9–0 nylon monofilament suture. The 9 rats in the third group were used as normal controls. Three animals from each group were sacrificed on days 8, 16, and 30 after injury. Light microscopic analysis was performed on semi-thin sections stained with 1% methylene blue, azure II, and basic fuchsin. Transmission electron microscopy was used to study and compare the ultrastructural changes in the epiligament. The statistical analysis of the obtained data was performed using the Kruskal-Wallis H test and Mood’s median test. The normal structure of the epiligament of the medial collateral ligament was presented by fibroblasts, fibrocytes, adipose cells, mast cells, collagen fibers, and neuro-vascular bundles. On days 8 and 16 postinjury, the epiligament appeared hypercellular and returned to its normal appearance on the thirtieth day postinjury. The electron microscopic study revealed the presence of different types of fibroblasts with the typical ultrastructural features of collagen-synthetizing cells. The comparative statistical analysis on the respective day showed that there was no statistically significant difference in the number of cells between spontaneously healing animals and animals recovering with suture application. These data further prove that spontaneous healing of the medial collateral ligament yields similar results to surgical treatment and may be used as a basis for the development of treatment regimens with improved patient outcome.

Are re-injured ligaments equivalent mechanically to injured ligaments: The role of re-injury severity?

The consequences of ligament re-injury have received limited attention. Although the mechanical properties of injured ligaments improve over time, these properties are never fully recaptured, rendering these injured ligaments susceptible to re-injury. Previous injury is a significant risk factor for recurrent injury, and this re-injury can result in longer absence from activity than the initial injury. A rabbit medial collateral ligament model was used to compare mechanically re-injured right medial collateral ligaments to injured left medial collateral ligaments. Two groups of different re-injury severity were investigated: ‘minor’ re-injury comparing transection re-injured right medial collateral ligaments to transection injured left medial collateral ligaments; ‘major’ re-injury comparing gap re-injured right medial collateral ligaments to transection injured left medial collateral ligaments. Initial injuries for both groups were right medial collateral ligament transections 1 week before re-injury. After 5–6 weeks of healing, mechanical testing was performed to determine (dimensionally) cross-sectional area; (structurally) medial collateral ligament laxity, failure load, and stiffness; and (materially) cyclic creep strain and failure stress. Because we wanted to evaluate whether the mechanical properties of re-injured ligaments were equivalent or, at least, no worse than injured ligaments, we used equivalence/noninferiority testing. This approach evaluates a research hypothesis of equivalence, rather than difference, and determines whether comparisons are ‘statistically equivalent’, ‘noninferior’, or ‘potentially inferior’. Transection re-injured and gap re-injured ligaments were ‘statistically equivalent’ structurally to transection injured ligaments. Transection re-injured ligaments were ‘noninferior’ both materially and dimensionally to transection injured ligaments. Gap re-injured ligaments were ‘potentially inferior’ both materially and dimensionally to transection injured ligaments. Two differences between the re-injuries, which affect healing, may explain the mechanical outcomes: the presence or lack of healing products and the proximity of ligament ends at the time of re-injury. Our findings suggest that (in the short term) there is a severity of re-injury below which there is no additional disadvantage to the healing process, mechanical behaviour, and resulting potential for re-injury.

A mathematical model of medial collateral ligament repair: migration, fibroblast proliferation and collagen formation

The partial rupture of ligament fibres leads to an injury known as grade 2 sprain. Wound healing after injury consists of four general stages: swelling, release of platelet-derived growth factor (PDGF), fibroblast migration and proliferation and collagen production. The aim of this paper is to present a mathematical model based on reaction-diffusion equations for describing the repair of the medial collateral ligament when it has suffered a grade 2 sprain. We have used the finite element method to solve the equations of this. The results have simulated the tissue swelling at the time of injury, predicted PDGF influence, the concentration of fibroblasts migrating towards the place of injury and reproduced the random orientation of immature collagen fibres. These results agree with experimental data reported by other authors. The model describes wound healing during the 9 days following such injury.

Histological and ultrastructural evaluation of the early healing of the lateral collateral ligament epiligament tissue in a rat knee model

Background

In this study, we evaluated the changes which occurred in the epiligament, an enveloping tissue of the ligament, during the ligament healing. We assessed the association of epiligament elements that could be involved in ligament healing.

Methods

Thirty-two 8-month old male Wistar rats were used in this study. In twenty-four of them the lateral collateral ligament of the knee joint was surgically transected and was allowed to heal spontaneously. The evaluation of the epiligament healing included light microscopy and transmission electron microscopy.

Results

At the eight, sixteenth and thirtieth day after injury, the animals were sacrificed and the ligaments were examined. Our results revealed that on the eight and sixteenth day post-injury the epiligament tissue is not completely regenerated. Till the thirtieth day after injury the epiligament is similar to normal, but not fully restored.

Conclusion

Our study offered a more complete description of the epiligament healing process and defined its important role in ligament healing. Thus, we provided a base for new strategies in ligament treatment.

Quadriceps tendon free graft augmentation for a midsubstance tear of the medial collateral ligament during total knee arthroplasty

Primary repair of a disrupted midsubstance MCL during TKA can provide satisfactory stability. However, in cases with poor soft tissue quality or a gap between the ligament ends, primary repair may not be feasible. In these cases, we have used an augmented repair. The purpose of this study is to describe the technique of augmented repair using a quadriceps tendon free graft and present our experience of five patients. A total of five patients underwent augmented repair of a transected MCL substance using a quadriceps tendon free graft. The patients were followed-up for a mean of 16 months. Augmented repair of the transected MCL substance was successful in all five patients, with a mean additional surgery time of 17 min, no coronal instability, a mean Knee Society Score of 87.0+/-2.7 (range, 85 to 90), and a mean function score of 85.0+/-3.5 (range, 80 to 90). There were no complications associated with the extensor mechanism. This data suggests that quadriceps tendon free graft augmentation might be a useful alternative for repairing midsubstance tears of the MCL in special situations, where the quality of the remaining tendon is poor, there is suspicion of stretching, and there is a small gap between both the repaired ligament ends resulting in late laxity.

Chitosan-based hyaluronan hybrid polymer fibre scaffold for ligament and tendon tissue engineering

To establish medical use of tissue engineering technology for ligament and tendon injuries, a scaffold was developed which has sufficient ability for cell growth, cell differentiation, and mechanical properties. The scaffold made from chitosan and 0.1 per cent hyaluronic acid has adequate biodegradability and biocompatibility. An animal experiment showed that the scaffold has less toxicity and less inflammation induction. Furthermore, in-vivo animal experiments showed that the mechanical properties of the engineered ligament or tendon had the possibility to stabilize the joint. It was shown that newly developed hybrid-polymer fibre scaffold has feasibility for joint tissue engineering.