The biomechanical and histological effects of posterior cruciate ligament rupture on the medial tibial plateau

Management of pediatric posterior cruciate ligament avulsion fractures: a systematic review

PURPOSE

Both open and arthroscopic surgical techniques have been used for PCL avulsion fractures. The goal of this study is to evaluate the effectiveness and safety of the different management strategies proposed for PCL avulsion fractures in children.

METHODS

A systematic literature review was performed utilizing Medline, Scopus, and EMBASE databases from 1977 to the present. PRISMA guidelines were followed. Data were selected and extracted by two independent reviewers. Inclusion criteria were clinical studies reporting injuries in pediatric patients with PCL avulsion injuries. Exclusion criteria were combined PCL and ACL injuries and ligamentous injuries requiring reconstruction. A subgroup analysis was performed between open reduction and arthroscopic surgeries.

FINDINGS/RESULTS

Twenty-six studies were included in this systematic review. Patient sex was reported in 39 patients with a higher number of males (32/39). The age range was 7-18 years old. In the open group, 30/31 patients had clinical improvement or returned to pre-injury activity level with two complications. Lysholm scores ranged from 66 to 99. In the arthroscopic group, 11/12 patients experienced clinical improvement or returned to normal activity levels with only one complication. Lysholm scores ranged from 90 to 100 with a mean of 95. In the non-operative group, 3/3 recovered with evidence of fracture healing, full or near full knee range of motion. One Lysholm score was reported 14 months after injury and was 100/100.

CONCLUSIONS

Open reduction and arthroscopic surgeries are effective and safe treatment options for pediatric PCL avulsion fractures-97% of open reduction and 92% of arthroscopic patients significantly improved symptoms. The complication rates for the open and arthroscopic groups were 11 and 9%, respectively. All three non-operative made full or near full recovery of pre-injury knee status.

LEVEL OF EVIDENCE IV

Systematic review of Level-II-IV studies. Prospero Registration No CRD42021290899.

Intercondylar notch volume in patients with posterior cruciate ligament tears and tibial avulsion injuries: a study applying computed tomography

BACKGROUND

Two relatively common forms of injury exist in the posterior cruciate ligament (PCL) after the onset of trauma: PCL tear and tibial avulsion fracture. The mechanism for the occurrence of these different forms of injury is not known. Herein, we aimed to investigate this mechanism by comparing the intercondylar notch parameters between patients with PCL tears and those with PCL avulsion fractures of the tibial insertion.

METHODS

Fifty-three patients with PCL tears (37 male, 16 female: median age of 37 years: range 18-54 years) and 46 patients with avulsion fractures of tibial insertion (33 male, 13 female: median age of 33 years: range 18-55 years) were included in this study. Three-dimensional computed tomography (CT) was applied to measure the intercondylar notch width index and intercondylar notch volume. The intercondylar notch volume was simulated as the truncated-pyramid shape. Measurements of the top and bottom areas of this model were conducted on the slice containing the most proximal (S₁) and most distal (S₂) levels of Blumensaat's line. Femoral condyle height (h) was defined as the vertical distance between two parallel planes, and the volume was calculated as h(S₁ + S₂ + √(S₁S₂))/3. The values of S₁, S₂, h, notch volume, the body mass index (BMI), intercondylar notch width (NW), femoral condylar width (FW) and notch width index (NWI) were compared among the PCL tear and avulsion-fracture groups.

RESULTS

The results show a significant difference in the S₂ and normalized intercondylar notch volumes among patients with PCL tears and tibial avulsion injuries. Patients with PCL tears have smaller S₂ and intercondylar notch volumes than those with tibial avulsion. There were no significant differences between the two groups in S₁ or the 2D notch measurement parameters, such as the NW, FW and NWI. In addition, logistic regression analysis revealed notch volume and body mass index (BMI) as two significant independent predictors for PCL tears.

CONCLUSION

Decreased intercondylar notch volume and increased BMI are associated with an increased incidence of PCL tears. The occurrence of PCL tears and tibial avulsion injuries is influenced by the femoral intercondylar notch volume, and the measurement of the notch volume could be useful for identifying patients at risk for PCL tears.

Allografts as alternative to autografts in primary posterior cruciate ligament reconstruction: a systematic review and meta-analysis

PURPOSE

Following posterior cruciate ligament (PCL) rupture, autografts and allografts are routinely used for its reconstruction. This study investigated the efficacy and safety of allografts for primary PCL reconstruction, comparing them to autografts in terms of patient-reported outcome measures (PROMs), functional tests, and complications.

METHODS

This study followed the PRISMA guidelines. PubMed, Web of Science, Google Scholar, Embase, and Scopus were accessed in October 2022. All the clinical studies investigating the outcomes of primary PCL reconstruction using allografts, or comparing the outcomes of allografts versus autografts, were accessed. The outcomes of interests were: instrumental laxity, range of motion (ROM), Telos stress radiography, drawer test, International Knee Documentation Committee (IKDC), Tegner Activity Scale, and the Lysholm Knee Scoring Scale. Data on complications were also recorded.

RESULTS

A total of 445 patients were included. The mean follow-up was 45.2 ± 23.8 months. The mean age of the patients was 30.6 ± 2.2 years. The time span between the injury and surgical intervention was 12.9 ± 10 months. Overall, 28% (125 of 445 patients) were women. Good baseline comparability was found between the two cohorts. No difference was found in terms of Lysholm Score, ROM, Tegner Scale, IKDC, arthrometer laxity, drawer test, and Telos stress radiography. No difference was found in the rates of anterior knee pain and revision.

CONCLUSION

Allografts can be considered a suitable alternative to autografts for PCL reconstruction.

LEVEL OF EVIDENCE

III.

Single versus double bundle in posterior cruciate ligament (PCL) reconstruction: a meta-analysis

Posterior cruciate ligament (PCL) reconstruction can be performed using single bundle (SB) and double bundle (DB) techniques. The present study investigated whether DB PCL reconstruction is superior to SB reconstruction in terms of patient reported outcome measures (PROMs) and joint stability. In December 2021 Embase, Google Scholar, Pubmed, Scopus databases were accessed. All clinical trials comparing SB versus DB reconstruction to address PCL insufficiency in skeletally mature patients were considered. Data from 483 procedures were retrieved. The mean follow-up was 31.0 (28.0 to 107.6) months, and the mean timespan between injury and surgery was 11.3 (6 to 37) months. The mean age of the patients was 29.3 ± 3.8 years. 85 of 483 patients (18%) were women. At a mean of 31.0 months post reconstruction, ROM (P = 0.03) was slightly greater in the SB group, while the Tegner score (P = 0.03) and the Telos stress (P = 0.04) were more favorable in the DB cohort. Similarity was found in instrumental laxity (P = 0.4) and Lysholm score (P = 0.3). The current evidence does not support the use of DB techniques for PCL reconstruction. Both methods could restore knee stability and motion with satisfactory short term patient reported outcome measures. Further high quality clinical trials are required to validate these results on a larger scale.

The effects of posterior cruciate ligament rupture on the biomechanical and histological characteristics of the medial collateral ligament: an animal study

Background

To investigate the effect of complete rupture of the posterior cruciate ligament (PCL) on the biomechanics and histology of the medial collateral ligament (MCL).

Materials and methods

Seventy-two male rabbits were randomly divided into two groups: the ruptured group was treated with complete PCL amputation, while the intact group was only subjected to PCL exposure without amputation. Eighteen rabbits were randomly sacrificed at 8, 16, 24, and 40 weeks after the operation, and their specimens were processed for mechanical tensile testing, nano-indentation experiments, hematoxylin-eosin (HE) staining, and picrosirius-polarization staining.

Results

There was no significant difference in the length and maximum displacement of the MCL between the ruptured group and the intact group at each time point. The maximum load of the ruptured group was significantly smaller than that of the intact group at 40 W. The elastic modulus and micro-hardness of the ruptured group increased significantly at 24 W and decreased significantly at 40 W. At 16 W and 24 W after PCL rupture, the number of type I collagen fibers and type III collagen fibers in the MCL of the ruptured group was significantly increased compared with that of the intact group. While the type I collagen fibers of the ruptured group were significantly decreased compared with the intact group at 40 W, there was no significant difference in type III collagen fibers between the ruptured group and the intact group.

Conclusion

PCL rupture has no significant effect on the mechanical and histological properties of MCL in a short period of time under physiological loading, but the histological and mechanical properties of MCL decrease with time.

Protective Effect of SIRT1 Activator on the Knee With Osteoarthritis

Osteoarthritis (OA), one of the most common chronic musculoskeletal disorders, is deemed to be correlated with aging. The SIRT1 activator, resveratrol, acts as a crucial regulator of aging and may have a potential therapeutic effect on OA. Rabbit OA models were established through destabilized medial meniscus surgery. A total of 40 healthy male New Zealand rabbits were divided into five groups: control group (sham operation), OA group, as well as low dose (LD), middle dose (MD), and high dose (HD) resveratrol-treated OA groups. 6 weeks after operation, 0.8 ml of normal saline was injected into the knee joints every other day in the control and OA groups, and 0.8 ml of 5, 10, and 15 μmol/L resveratrol was injected into the knee joints every other day in the LD, MD, and HD group, respectively. The rabbits were sacrificed 2 weeks after medication, and the articular cartilage of the knee joint was collected for Micro-CT, histology and Western blot analysis. Obvious articular cartilage lesion and joint space narrowing were detected in the OA group. Compared with the OA group, less osteoarthritic changes were observed in the MD and HD groups. The MD and HD groups had significantly lower bone volume fraction, trabecular number and Mankin scores than the LD and OA groups (p < 0.05). No significant difference was found between the OA and LD groups (p > 0.05). The expressions of SIRT1 and p53 detected by western blot were consistent with the aforementioned findings. Therefore, resveratrol can activate the SIRT1 gene to play a protective role in the OA process by inhibiting chondrocyte apoptosis, trabecular bone number increasing of the subchondral bone, as well as elevation of bone density. It demonstrated the importance of SIRT1 in maintaining articular cartilage health and provided a promising therapeutic intervention in the treatment of OA.

Characterization of articular cartilage homeostasis and the mechanism of superior cartilage regeneration of MRL/MpJ mice

This study investigated articular cartilage (AC) homeostasis and different signaling pathways involved in the superior cartilage regeneration of Murphy Roths large (MRL/MpJ) mice previously reported. We collected uninjured and destabilized medial meniscus (DMM)-injured knees from 8-wk-old C57BL/6J and MRL/MpJ mice. We used micro-computed tomography (microCT), histology, and immunohistochemistry to evaluate AC homeostasis and repair. We used the ear punch model to investigate the role of angiogenesis and inflammation in the superior healing of MRL/MpJ mice. We found fewer β-catenin and more pSMAD5 positive cells in the uninjured AC of MRL/MpJ mice than that from C57BL/6J mice. MRL/MpJ mice exhibited better AC repair in DMM-induced OA, as indicated by microCT results, Alcian blue, and Safranin O staining. Mechanistically, fewer β-catenin, pSMAD2-, pSMAD3-, a disintegrin and metalloproteinase with thrombospondin motifs 4-, matrix metalloproteinase (MMP) 9-, and MMP13-positive cells and more proliferating cell nuclear antigen- and pSMAD5-positive cells were found in the DMM-injured AC in MRL/MpJ mice than in normal mice. The accelerated ear wound healing of MRL/MpJ mice correlated with enhanced angiogenesis and macrophage polarization toward the M2a phenotype through elevated IL-10 and IL-4 expressing cells. Collectively, our study revealed that down-regulation of pSMAD2/3, β-catenin, and MMPs and up-regulation of pSMAD5 and M2a macrophage polarization contribute to the enhanced cartilage repair observed in MRL/MpJ mice.-Deng, Z., Gao, X., Sun, X., Amra, S., Lu, A., Cui, Y., Eltzschig, H. K., Lei, G., Huard, J. Characterization of articular cartilage homeostasis and the mechanism of superior cartilage regeneration of MRL/MpJ mice.

The morphology and histology study on rabbit degenerated medial meniscus after posterior cruciate ligament rupture

The morphology and histology changes in the medial meniscus after posterior cruciate ligament (PCL) rupture are poorly understood. Forty-eight rabbits were divided into matched mode pairs; each rabbit had an experimental side, in which the PCL was transacted, and a control side. At the 4, 8, 16 and 24 weeks after the PCL transection, each of the 12 rabbits was killed. Histology was performed to detect the expression of the tissue inhibitors of metalloproteinases-1 (TIMP-1), matrix metalloproteinase (MMP)-1 and MMP-13 in the medial meniscus. We found that medial meniscus displayed significant degenerative characteristics in morphology. The histological evaluation of the degeneration found that the expression levels of TIMP-1, MMP-1 and MMP-13 in the medial meniscus were higher in the experiment side than those in the control side (P<0.05). The expression of both TIMP-1 and MMP-13 was initially elevated and then decreased. The MMP-1 expression reached its peak swiftly and then maintained a relatively high level. There were clear time-dependent degenerative changes in the histology of the medial meniscus after PCL rupture. The high expression of TIMP-1, MMP-1 and MMP-13 in the cartilage may be responsible for the degeneration, and PCL rupture may trigger meniscus degradation and ultimately osteoarthritis.