Medial meniscal extrusion greater than 4 mm reduces medial tibiofemoral compartment contact area: a biomechanical analysis of tibiofemoral contact area and pressures with varying amounts of meniscal extrusion

PURPOSE

The primary objective of this study is to evaluate the contact areas, contact pressures, and peak pressures in the medial compartment of the knee in six sequential testing conditions. The secondary objective is to establish how much the medial meniscus is able to extrude, secondary to soft tissue injury while keeping its roots intact.

METHODS

Ten cadaveric knees were dissected and tested in six conditions: (1) intact meniscus, (2) 2 mm extrusion, (3) 3 mm extrusion, (4) 4 mm extrusion, (5) maximum extrusion, (6) capsular based meniscal repair. Knees were loaded with a 1000-N axial compressive force at 0°, 30°, 60°, and 90° for each condition. Medial compartment contact area, average contact pressure, and peak contact pressure data were recorded.

RESULTS

When compared to the intact state, there was no statistically significant difference in medial compartment contact area at 2 mm of extrusion or 3 mm of extrusion (n.s.). There was a statistically significant decrease in contact area compared to the intact state at 4 mm (p = 0.015) and maximum extrusion (p < 0.001). The repair state was able to improve medial compartment contact area, and there was no statistically significant difference between the repair and the intact states (n.s.). No significant differences were found in the average contact pressure between the repair, intact, or maximum extrusion conditions at any flexion angle (n.s.). No significant differences were found in the peak contact pressure between the repair, intact, or maximum extrusion conditions at any flexion angle (n.s.).

CONCLUSION

In this in vitro model, medial meniscus extrusion greater than 4 mm reduced medial compartment contact area, but meniscal extrusion did not significantly increase pressure in the medial compartment. Additionally, meniscal centralization was effective in restoring the medial tibiofemoral contact area to intact state when the meniscal extrusion was secondary to meniscotibial ligament injury. The diagnosis of meniscal extrusion may not necessarily involve meniscal root injury. Since it is known that meniscal extrusion greater than 3 or 4 mm has a biomechanical impact on tibiofemoral compartment contact area and pressures, specific treatments can be established. Centralization restored medial compartment contact area to the intact state.

Larger Chondral Lesions Treated with Collagen Membrane - Matrix-Induced Autologous Chondrogenesis - Show Larger Increase in Clinical Scores

Objective  To evaluate clinically and radiologically the results of the treatment of chondral lesions using collagen membrane - autologous matrix-induced chondrogenesis (AMIC).

Methods  This is a series of observational cases, in which 15 patients undergoing AMIC were analyzed. The clinical evaluation was made by comparing the Lysholm and International Knee Document Commitee (IKDC) scores in the pre- and postoperative period of 12 months, and radiological evaluation using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score in the same postoperative period.

Results  The mean age of the patients was 39.2 years old, and the mean size of the chondral lesions was 1.55cm ² . There was a significant improvement in clinical scores, with a mean increase of 24.6 points on Lysholm and of 24.3 on IKDC after 12 months. In the radiological evaluation, MOCART had a mean of 65 points. It was observed that the larger the size of the lesion, the greater the improvement in scores.

Conclusion  Evaluating subjective clinical scores, the treatment of chondral lesions with the collagen membrane showed good results, as well as the evaluation of MOCART, with greater benefit in larger lesions.

Comparative Study of the Function and Quality of Life of Patients Submitted to Total Knee Arthroplasty with Fixed and Mobile Tibial Platforms

Objective  To compare the function and quality of life of patients undergoing total knee arthroplasty (TKA) with fixed tibial platform and mobile tibial platform.

Methods  We evaluated 240 patients with knee osteoarthritis, randomized into two groups - Group A consisted of 120 patients who underwent TKA with fixed tibial platform, and the B group, consisting of 120 patients who underwent mobile platform arthroplasty. Patients were accessed according to the function and quality of life by the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the Short Form Health Survey (SF-36), and pain scores by visual analog scale (VAS) of pain, preoperatively and at 6 months, 1 year, 2 years, 4 years and 8 years of surgery.

Results  Regarding the various domains of the SF-36, we observed that the average behavior of functional capacity scores, physical aspects, pain and emotional aspects in the patient groups were statistically different during follow-up. The other domains of quality of life showed no mean differences. Regarding the pain assessed by VAS and WOMAC pain scores, we can see that it showed a mean change in follow-up in both patient groups. However, at 2 years of follow-up, they were statistically worse in group A, equaling group B in the other moments.

Conclusion  After 2 years of follow-up, we observed that pain scores and VAS were lower in the fixed platform group. However, these differences did not remain in the mid-term, suggesting that the mobile tibial platform arthroplasty has a short-term advantage, and may help in the rehabilitation process.

Higher Axial Tibiofemoral Rotation and Functional Outcomes with Mobile-Bearing Compared with Fixed-Bearing Total Knee Arthroplasty at 1- but Not at 2-Year Follow-Up-A Randomized Clinical Trial

The objective of this study was to determine in vivo knee kinematics and clinical outcomes of patients who underwent fixed- and mobile-bearing total knee arthroplasty (TKA) at 1- and 2-year follow-up. This prospective double-blinded randomized controlled trial was performed from November 2011 to December 2012. A total of 64 patients were randomized to fixed- and mobile-bearing TKA groups (32 patients in each group). All patients were evaluated with the following: three-dimensional in vivo knee kinematics analysis during gait, stepping up and stepping down stair steps, and getting up from and sitting on a chair; and knee range of motion and patient-reported outcome measures (Knee Outcome Survey Activities of Daily Living Scale [KOS-ADLS] and pain visual analog scale [VAS]) at 1- and 2-year follow-up. Descriptive statistics (means, standard deviations, and percentages) were calculated for all variables. The Kolmogorov-Smirnov test was used to test if variables were normally distributed. A Student's t-test was used to compare continuous variables between patients in the two groups. The chi-square test was used to compare the groups with respect to categorical variables. The α level for statistical significance was set at p < 0.05. The mean axial tibiofemoral rotation in patients who underwent mobile-bearing TKA was significantly higher during gait (13.3 vs. 10.7), stepping up (12.8 vs. 10) stair steps, and getting up (16.1 vs. 12.1) from a chair compared with fixed-bearing TKA patients at 1-year follow-up (p < 0.05). KOS-ADLS function score was significantly higher in the mobile-bearing compared with the fixed-bearing TKA group (32 vs. 27.7) at 1-year follow-up (p < 0.05). No significant difference in kinematics and clinical outcomes between fixed- and mobile-bearing TKA groups was observed at 2-year follow-up (p > 0.05). Based on the results of this study, mobile-bearing TKA allowed a higher degree of rotation when walking, stepping up stair steps, and standing up from a chair, and had higher functional outcomes compared with fixed-bearing TKA at 1-year follow-up. However, no difference in in vivo kinematics or in clinical outcomes was observed between fixed- and mobile-bearing prostheses at 2-year follow-up.

THE 50 MOST CITED ARTICLES IN THE BRAZILIAN MEDICAL LITERATURE ON KNEE SURGERY

OBJECTIVE

To provide an analysis of the 50 most cited articles on knee surgery in the Brazilian medical literature.

METHODS

This is a study of systematic review and meta-analysis, level of evidence 3. It was carried out through search in the SCOPUS database to identify scientific articles published in the Brazilian medical literature. Eighty-six Brazilian journals were analyzed, and articles with ten or more citations and which had the word "joelho" or "knee" in the title, abstract or keywords were selected.

RESULTS

All articles were published as of the year 2000 in 14 journals. The Journal Clinics presented the largest number of publications, followed by Acta Ortopédica Brasileira. The main focus of the studies was on anatomy and biomechanics, mainly from Brazilian authors. Most of the authors were Brazilian, from Brazilian and public research institutions.

CONCLUSION

Biometric analysis has been gaining ground in recent years, but its interpretation must consider various aspects related to the paramount analytical importance.

Pediatric Anterior Cruciate Ligament Reruptures Are Related to Lower Functional Scores at the Time of Return to Activity: A Prospective, Midterm Follow-up Study

Background:

Skeletally immature patients show a higher rate of anterior cruciate ligament (ACL) reruptures. A better understanding of the risk factors for an ACL rerupture in this population is critical.

Purpose/Hypothesis:

The objective of this study was to analyze preoperative, intraoperative, and postoperative characteristics of pediatric patients undergoing ACL reconstruction and determine the relationship of these factors with an ACL rerupture. It was hypothesized that patients with worse activity scores and knee function at the time of return to activity would have a higher rate of ACL reruptures at midterm follow-up. Additionally, it was hypothesized that most ACL reruptures would occur before age 20 years in the study population.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

A total of 65 skeletally immature patients (age <16 years) with ACL ruptures underwent reconstruction with a quadruple hamstring tendon graft between 2002 and 2016. Of these patients, 52 were available for the study. Patient characteristics, surgical details, Tegner and Lysholm scores, and ACL reconstruction outcomes were recorded. Patients were analyzed and compared according to ACL rerupture occurrence.

Results:

Of the 52 patients, 18 (34.6%) experienced an ACL rerupture after reconstruction. The majority of reruptures (77.8%) occurred before age 20 years. There were 2 patients who sustained ACL reruptures during the rehabilitation period before they returned to activity. The majority of reruptures occurred after 12 months (83.2%), with 66.6% occurring after 24 months. Upon returning to activity between 6 and 9 months postoperatively, patients who ended up with intact ACL grafts reported 69% higher mean Tegner scores (P = .006) and 64% higher mean Lysholm scores than patients who sustained ACL reruptures (P < .001). Within the limits of this study, we could identify no statistical relationship between the rate of ACL reruptures and different sport types, surgical techniques, or associated injuries (P > .05).

Conclusion:

Skeletally immature patients who underwent ACL reconstruction and sustained ACL reruptures had lower Tegner and Lysholm scores upon returning to activity than patients without ACL reruptures. In addition, most ACL reruptures occurred in patients younger than 20 years (77.8%) and after 24 months postoperatively (66.6%).

ASSESSMENT OF THE REGENERATION CAPACITY OF SEMITENDINOSUS AND GRACILIS TENDONS

Objectives:

To evaluate the regenerative capacity of gracilis (G) and semitendinosus (ST) tendons, to examine the sensitivity and specificity of signs and symptoms in the assessment of hamstring tendons, and to assess the thickness and insertion site of regenerated tendons.

Methods:

Thirty sequential knees were subjected to anterior cruciate ligament reconstruction with semitendinosus and gracilis tendons. After surgery, the patients were followed up clinically with physical examination and magnetic resonance imaging (MRI).

Results:

Overall, 36.66% of the tendons were visible on MRI, whereas 83.33% were palpable. On MRI, the distal insertion site of the regenerated semitendinosus tendon was visible proximal to the landmark of the medial femoral condyle in 28%, at the same level in 16%, and distally in 56% of the cases. Gracilis tendon insertion was visible proximally in 36.66% of cases, at the same level in 10%, and distally in 53.33%. Eleven knees exhibited complete regeneration.

Conclusion:

Partial or total regeneration of the ST and G tendons was apparent on MRI. Palpation is effective for evaluating regeneration of the ST and G tendons; however, MRI is still the gold standard. ST and G tendons regenerated completely in only a small percentage of patients, limiting reuse as a graft in cases with new ligament injuries of the knee. Level of Evidence II, Prospective comparative study.

Ultrasonography for evaluation of hamstring tendon diameter: is it possible to predict the size of the graft?

Objective

Perform the preoperative measurement of the hamstring tendons using ultrasound imaging, validating and correlating the measured value with that found during surgical reconstruction of the ligament.

Methods

A cross-sectional study was carried out with 24 patients who underwent ultrasonographic measurement of the semitendinosus and gracilis muscle tendons and were subsequently submitted to surgical reconstruction of the ACL, with ipsilateral semitendinosus and gracilis tendon grafting.

Results

The patients’ ages ranged from 16 to 43 years, with a mean of 24.8 years (SD = 8.4 years), 79.2% were men, and the distribution by side was 41.7% right knees and 58.3% left knees. A non-significant correlation coefficient was found between the area calculated by ultrasound (2 × semitendinosus area + 2 × gracilis area) and the intraoperative measurement (r = 0.16; p = 0.443). No evidence of a difference between intraoperative measurements <8 mm and ≥8 mm was found for the area calculated by the ultrasound (p = 0.746). The difference observed between the groups was −0.01 (95% CI: −0.09 to 0.07).

Conclusion

Preoperative ultrasound imaging of the semitendinosus and gracilis tendons does not present a statistically significant correlation with the intraoperative measurement of the quadruple hamstring graft for ligament reconstruction.

Higher Gene Expression of Healing Factors in Anterior Cruciate Ligament Remnant in Acute Anterior Cruciate Ligament Tear

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction with remnant preservation has been described and related to potential advantages. Literature is lacking regarding gene expression of potential factors related to ligament healing in the ACL remnant and its relation to time from injury.

HYPOTHESIS

The mRNA expression of ligament healing factors in the ACL remnant would be higher in acute tears (<3 months from injury) than in intermediate (3-12 months) and chronic (>12 months) injuries.

STUDY DESIGN

Controlled laboratory study.

METHODS

Gene expression of 21 genes related to ligament healing factors was analyzed in 46 ACL remnants biopsied during surgical reconstruction with quantitative real-time polymerase chain reaction technique. Specimens were divided into 3 groups according to time from injury: acute (<3 months from injury; n = 19), intermediate (3-12 months; n = 12), and chronic (>12 months; n = 15). Histological and immunohistochemical evaluation was performed by analysis of hematoxylin and eosin, CD-34, and S-100 staining.

RESULTS

Expression of COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, COL12A1, LOX, PLOD1, and TNC genes in ACL remnant was greater in acute compared with chronic injuries. COL1A1, COL5A1, COL12A1, and TNC genes were also expressed more in the acute group compared with the intermediate group. Furthermore, expression of the genes COL1A1 and COL5A2 was significantly higher in female than in male patients. No difference in the number of blood vessels and mechanoreceptors among groups was observed in the microscopic evaluation.

CONCLUSION

The present study demonstrates that expression of COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, COL12A1, LOX, PLOD1, and TNC genes in ACL remnant is greater in acute (<3 months from injury) compared with chronic (>12 months) injuries. Furthermore, COL1A1, COL5A1, COL12A1, and TNC genes were expressed more in the acute group compared with the intermediate group (3-12 months from injury).

CLINICAL RELEVANCE

ACL reconstructions with remnant preservation should be performed in patients with acute injuries, as in these cases the ACL remnant may present the greatest healing potential.

Quadriceps Strength Deficit at 6 Months After ACL Reconstruction Does Not Predict Return to Preinjury Sports Level

Background:

There is a lack of literature-based objective criteria for return to sport after anterior cruciate ligament (ACL) injury. Establishing such objective criteria is crucial to improving return to sport after ACL reconstruction (ACLR).

Hypotheses:

Patients who return to their preinjury level of sport will have higher isokinetic, postural stability, and drop vertical jump test scores 6 months after surgery and greater patient satisfaction compared with those who did not. Additionally, quadriceps strength deficit cutoff values of 80% and 90% would differentiate patients who returned to preinjury sports level from those who did not.

Study Design:

Cohort study.

Level of Evidence:

Level 3.

Methods:

A retrospective search was conducted to identify all patients who underwent ACLR and completed isokinetic evaluation, postural stability analysis, and drop vertical jump testing at 6 months postoperatively. Patients were asked to complete 3 questionnaires at a minimum 1 year after surgery. Chi-square and logistic regression analyses were used for categorical dependent variables, while the Student t test, Pearson correlation, or analyses of variance with Bonferroni post hoc testing were used for continuous dependent variables. A post hoc power analysis was completed. Based on the results regarding correlations between return to preinjury level and all other variables, effect sizes from 0.24 to 3.03 were calculated. With these effect sizes, an alpha of 0.05 and sample size of 58, a power ranging from 0.15 to 0.94 was calculated.

Results:

The rates of return to preinjury level and to any sports activity were 53.4% and 84.4%. Those who were able to return to their preinjury level of sport (n = 33) showed significantly higher Lysholm (91.6 ± 9.7 vs 76.7 ± 15.4) and International Knee Documentation Committee (IKDC) (83.6 ± 10.6 vs 69.8 ± 14.6) values compared with those who were unable to return to their preinjury level of sport (n = 25) (P < 0.001). No significant differences were found for the clinical evaluations between those who were and those who were not able to return at the same level for the clinical evaluations (isokinetic evaluation, postural stability, drop vertical jump test) (P > 0.05). No significant differences were found when comparing quadriceps strength deficit with cutoff values of 80% and 90% for return to preinjury activity level (Tegner), Lysholm, and IKDC scores.

Conclusion:

Quadriceps strength deficit, regardless of cutoff value (80% or 90%), at 6 months after ACLR does not predict return to preinjury level of sport. Patients who returned to sport at their preinjury level were more satisfied with their reconstruction compared with those who did not.

Clinical Relevance:

Quadriceps strength deficit is not a reliable predictor of return to sports, and therefore it should not be used as the single criterion in such evaluations.

Relationship Between the Middle Genicular Artery and the Posterior Structures of the Knee: A Cadaveric Study

Background:

The middle genicular artery (MGA) is responsible for the blood supply to the cruciate ligaments and synovial tissue. Traumatic sports injuries and surgical procedures (open and arthroscopic) can cause vascular damage. Little attention has been devoted to establish safe parameters for the MGA.

Purpose:

To investigate the anatomy of the MGA and its relation to the posterior structures of the knees, mainly the posterior capsule and femoral condyles, and to establish safe parameters to avoid harming the MGA.

Study Design:

Descriptive laboratory study.

Methods:

Dissection of the MGA was performed in 16 fresh, unpaired adult human cadaveric knees with no macroscopic degenerative or traumatic changes and no previous surgeries. The specimens were meticulously evaluated with emphasis on preservation of the MGA. The distances from the MGA to the medial and lateral femoral condyles were measured. The Mann-Whitney test was used for statistical analysis.

Results:

In all specimens, the MGA emerged from the anterior aspect of the popliteal artery, distal to the superior genicular arteries, and had a short distal trajectory toward the posterior capsule where it entered proximal to the oblique popliteal ligament. The artery lay in the midportion between the condyles. The distance between the posterior aspect of the tibia and the point of entry of the MGA into the posterior joint capsule was 23.8 ± 7.3 mm (range, 14.72-35.68 mm). There was no correlation between an individual’s height and the distance of the entrance point of the MGA into the posterior joint capsule to the posterior superior corner of the tibia.

Conclusion:

The middle genicular artery lies in the midportion between the medial and lateral femoral condyles.

Clinical Relevance:

This knowledge is important for the preservation of the blood supply during posterior knee surgical procedures and to settle a secure distance between the posterior aspect of the tibia and the MGA input. This could decrease and prevent iatrogenic vascular injury risk to the MGA.

An anatomic study of the posterior septum of the knee

PURPOSE

To evaluate the posterior septum of the knee and determine the presence of a safe zone that could be removed, without significant damage to blood vessels and nerves.

METHODS

Nineteen fresh unpaired adult human cadaveric knees, with no macroscopic degenerative or traumatic changes, were used in this study. Microscopic evaluation was performed by analysis of H&E, CD-34, and S-100 staining.

RESULTS

The posterior septum of the knee is rich in type II and type IV mechanoreceptors and blood vessels. The superior half has a greater number of blood vessels (21.52 ± 6.36 v 12.05 ± 4.1, P < .001), higher-caliber vessels (2.2 ± 0.89 μm v 1.41 ± 0.45 μm, P < .006), and a greater number of mechanoreceptors per field (type II, 1.8 ± 1.8 v 0.42 ± 1, P = .04; type IV, 22.6 ± 14 v 14.5 ± 9.4, P = .04) than the inferior half of the septum.

CONCLUSIONS

This study has shown that the posterior septum of the knee is highly vascularized and has a great number of type II and IV mechanoreceptors. The presence of these structures is significantly higher in the superior half of the septum.

CLINICAL RELEVANCE

If debridement of the posterior septum is necessary, it should be done at the inferior aspect so that a greater number of blood vessels and mechanoreceptors can be preserved.