Effects of an untreated medial meniscal ramp lesion on histological deterioration findings of the medial meniscus: A study in a porcine anterior cruciate ligament reconstruction model

Purpose

To evaluate the effect of untreated medial meniscal ramp lesions (MMRLs) on the tendon graft after anterior cruciate ligament (ACL) reconstruction and histological findings of medial meniscus (MM) in a porcine a model.

Methods

A total of 17 pigs were divided into two groups: (1) the untreated MMRL group (UM group, n = 9) and (2) intact MM group (n = 8) and euthanized 12 weeks after surgery. The specimens were then tested cyclically and loaded to failure. Side-to-side differences (SSDs) in translation under cyclic loading and structural properties were analyzed. Histological evaluation of the MM was also performed.

Results

No significant differences in the SSD in translation during the cyclic testing (UM group, 0.3 ± 0.4 mm; intact MM group, 0.1 ± 1.4 mm), upper yield load (UM group, 476.3 ± 399.9 N; intact MM group, 643.2 ± 302.9 N), maximum load (UM group, 539.5 ± 265.8 N; intact MM group, 705.8 ± 282.6 N), linear stiffness (UM group, 63.5 ± 39.0 N/mm; intact MM group, 73.7 ± 60.1 N/mm) and elongation at failure (UM group, -4.6 ± 16.3 mm; intact MM group, 2.3 ± 6.6 mm) were observed. However, the UM group had significantly worse Modified Mankin's histological grading scores (1.8 ± 0.4 [1-2] vs. 0 ± 0 [0]; p < 0.001) and Modified Copenhaver classification scores (6.6 ± 2.4 [2-9] vs. 0.7 ± 1.1 [0-3]; p < 0.001) than did the intact MM group.

Conclusion

Untreated MMRLs showed postoperative histological deterioration.

Level of Evidence

Level IV.

Posterior Displacement of Meniscal Ramp Lesion Is Observed on Flexed Knee Magnetic Resonance Imaging of Anterior Cruciate Ligament-Deficient Knees

PURPOSE

To confirm whether posterior displacement of the detached meniscocapsular structure in ramp lesions could be observed on magnetic resonance imaging (MRI) in the flexed knee position and to clarify whether this displacement on MRI is related to greater anterior knee laxity.

METHODS

This retrospective comparative trial study included 50 patients with anterior cruciate ligament injuries in whom attendant ramp lesions were observed on preoperative MRI. All patients underwent 3-T MRI at 120° of knee flexion preoperatively. The gap distance of the ramp lesion on sagittal slices was measured, and a distance greater than 1 mm was classified as gap positive. Additionally, joint effusion in the posteromedial recess was quantitatively evaluated by measuring the surface area of joint fluid. Prior to surgery, the side-to-side difference in anterior tibial translation (ATT) on stress radiographs at 20° of knee flexion was measured to evaluate anterior knee laxity. During anterior cruciate ligament reconstruction, the length of the ramp lesion was measured by a scale from the posteromedial portal.

RESULTS

Of the 50 knees, 29 had ramp lesion gaps greater than 1 mm on MRI at knee flexion. The gap-positive group had a significantly greater side-to-side difference in ATT (9.6 ± 3.6 mm vs 5.0 ± 2.7 mm, P < .001) and significantly larger ramp lesion length (15.7 ± 4.9 mm vs 11.7 ± 3.9 mm, P = .002) than the gap-negative group. The gap-positive group also had a significantly greater amount of joint effusion than the gap-negative group (P < .001).

CONCLUSIONS

Posterior displacement of the detached meniscocapsular structure in ramp lesions can be observed on MRI at knee flexion and is related to greater anterior knee laxity, lesion size, and joint effusion.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.

Comparison of postoperative clinical outcome in medial-pivotal and gradually reducing radius design cruciate-retaining total knee arthroplasty-A multicenter analysis of propensity-matched cohorts

Purpose

To clarify differences in surgery duration, postoperative knee range of motion (ROM), anterior and posterior (AP) laxity, and Forgotten Joint Score (FJS) in patients undergoing medial-pivot (MP) and GRADIUS cruciate-retaining (CR) total knee arthroplasty (TKA) surgeries.

Methods

We examined patients who underwent either MP or CR TKA at six different Japanese centres. Patients were propensity score matched for age, sex, and preoperative hip-knee angle (HKA). We compared the groups' average surgery duration, postoperative knee ROM, AP laxity, and FJS 1 year after surgery.

Results

There were 86 study patients: 43 MP and 43 CR TKA matched for age, sex, and preoperative HKA. The MP group enjoyed a significantly shorter surgery duration (89.1 ± 10.9 mins vs. 95.7 ± 12.0 mins, p = 0.0091) and significantly better postoperative knee flexion than the CR group (123.7 ± 9.1° vs. 115.3 ± 12.4°, p < 0.001). The MP had significantly smaller postoperative AP laxity with 30° of knee flexion than the CR group (3.4 ± 1.3 vs. 5.6 ± 2.2 mm, p < 0.001). Conversely, postoperative AP laxity with 90° of knee flexion was significantly larger for the MP group (3.6 ± 1.3 vs. 2.7 ± 1.9 mm, p = 0.0098). There were no between-group differences in postoperative FJS.

Conclusions

The MP group showed better postoperative knee flexion, midrange AP knee stability, and shorter surgery duration.

Level of Evidence

Level III, retrospective comparative study.

Association between intraoperative findings and postoperative knee range motion after cruciate-retaining total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) alleviates pain and improves daily living activities in individuals with end-stage osteoarthritis of the knee. However, up to 20% of patients have sub-optimal outcomes after TKA.

OBJECTIVE

No studies have clarified the intraoperative factors that affect postoperative range of motion (ROM) after cruciate-retaining (CR) TKA. Thus, this study aims to clarify these factors.

METHODS

Patients with knee osteoarthritis with varus knee deformity who underwent CR-TKA between May 2019 and December 2020 were included in this study. One year after surgery, patients were stratified into two groups based on knee flexion: Group F (over 120∘) and Group NF (below 120∘). Patient backgrounds including age, body mass index, hip knee angle, preoperative range of motion for both extension and flexion, intraoperative center joint-gap measurements of 0∘, 30∘, 45∘, 60∘, 90∘, and 120∘ of knee flexion using a tensor, intraoperative anterior-posterior (AP) laxity measurements of 30∘ and 90∘ of knee flexion using an instrumental laximeter were compared between the groups. Univariate analyses between the groups were used to construct the initial model. The receiver operating characteristic curve was also analyzed. The predictive variables included in the final model were selected by stepwise backward elimination.

RESULTS

Intraoperative AP laxity with 30∘ of knee flexion smaller than 10.8 mm was a significant positive prognostic factor (OR: 1.39, 95% CI: 1.08-1.79, P= 0.011) of postoperative ROM over 120∘ of knee flexion one year after surgery. The sensitivity, specificity, PPV, and NPV were 70.9%, 82.4%, 92.9%, and 46.7%, respectively.

CONCLUSION

Intraoperative AP laxity smaller than 10.8 mm was a significant positive predictive factor for obtaining knee flexion greater than 120∘ one year after surgery when using CR-TKA and its PPV was high up to 92.9%.

Increased Bone Plug Depth From the Joint Increases Tunnel Enlargement in Anterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone Autograft With Suspensory Femoral Fixation

Purpose

To determine a safe bone plug depth fixation zone based on early tunnel enlargement rates in anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) autograft with suspensory femoral fixation.

Methods

Patients who had undergone rectangular tunnel ACL reconstruction using BPTB autograft with suspensory femoral fixation were retrospectively identified. Femoral and tibial tunnel aperture areas were measured on computed tomography 2 weeks and 6 months after surgery to calculate rates of femoral and tibial tunnel enlargement (FTE and TTE), respectively. Femoral bone plug depth (FBPD) and tibial bone plug depth (TBPD) were defined as the distance of the tip of the plug from the respective joint lines. Optimal FBPD and TBPD cutoff values were calculated for the following rates of FTE and TTE, respectively: 0%, 15%, 30%, and 50%.

Results

Sixty-four patients (19 females, 45 males; mean age, 29.5 ± 12.3 years) were included in the study. The femoral and tibial tunnel apertures significantly enlarged over time. FBPD (P < .001; r = 0.607) and TBPD (P = .013; r = 0.308) were positively correlated with FTE and TTE, respectively. The optimal FBPD cutoff value was 2.8 mm for FTE rates of 0% and 15%, 3.6 mm for 30%, and 6.0 mm for 50%. The optimal TBPD cutoff value was 1.48 mm for a 0% TTE rate and 5.1 mm for those higher. The cutoff value specificities were lower for the tibial tunnel than the femoral tunnel for each tunnel enlargement rate.

Conclusion

Early tunnel enlargement and bone plug depth were significantly correlated in bone the femoral and tibial tunnels. The degree of correlation was higher in the femoral tunnel. To minimize bone tunnel enlargement, the distal end of the femoral bone plug should be placed less than 2.8 mm from the tunnel aperture.

Level of Evidence

Level IV, therapeutic case series.

The comparison of dexamethasone and triamcinolone periarticular administration in total knee arthroplasty: retrospective cohort study

Background

Intraoperative periarticular injection of corticosteroid effectively reduces perioperative pain in total knee arthroplasty (TKA). However, which corticosteroid is most effective for intraoperative periarticular injection remains controversial. We compared the effects of corticosteroids between dexamethasone and triamcinolone acetonide periarticular administration for reducing pain and postoperative nausea and increasing fasting blood glucose concentrations during the perioperative period following TKA.

Methods

One hundred and two patients who underwent TKA from August 2018 to September 2020 were divided into two groups: one received 10 mg dexamethasone for intraoperative periarticular injection and another receiving 40 mg triamcinolone acetonide. Postoperative pain scores at rest and during walking and nausea scores were recorded using a 0-to-10 Numerical Rating Scale. C-reactive protein (CRP) and fasting blood glucose levels were measured pre- and postoperatively.

Results

Pain scores in the triamcinolone group were significantly lower than in the dexamethasone group at rest 7 days postoperatively (1.5 vs. 2.0; p = 0.046) and while walking at both 72 h (3.9 vs. 4.8; p = 0.008) and 7 days postoperatively (3.2 vs. 4.0; p = 0.03). The CRP levels in the triamcinolone group were significantly lower than in the dexamethasone group at 7 days postoperatively (1.6 mg/dl vs. 3.0 mg/dl: p < 0.001). The fasting blood glucose levels at 1 day postoperatively were increased in both groups but not significantly different between the groups. No significant differences in the nausea score were noted between the groups.

Conclusions

Triamcinolone acetonide periarticular administration provided greater pain relief by reducing inflammation to a greater degree than dexamethasone.

Medial meniscus extrusion as a predictor for a poor prognosis in patients with spontaneous osteonecrosis of the knee

BACKGROUND

Risk factors for the progression of spontaneous osteonecrosis of the knee (SONK) remain unclear. The purpose of this study was to investigate the association between magnetic resonance imaging (MRI) findings of the meniscus and the prognosis of SONK.

METHODS

A total of 78 consecutive patients (female 85%; mean age 75.6 ± 7.2 years old) diagnosed with SONK were included. Of these, 30 patients did not receive surgery within 1 year from the onset of SONK (conservative group), while the remaining 48 patients underwent unicompartmental knee arthroplasty due to worsening of symptoms (UKA group). Using MRI findings obtained within 3 months of the onset, we compared the types of meniscus tear and medial meniscus extrusion between the conservative group and UKA group. We performed a receiver operating characteristics (ROC) analysis to estimate the cut-off value.

RESULTS

Patients in the UKA group showed greater medial meniscus extrusion (absolute value, 4.2 mm ± 1.9 vs. 2.8 mm ± 1.2, P = 0.001; relative percentage of extrusion (RPE), 45.7% ± 21.5 vs. 30.7% ± 12.9, P = 0.001) and a higher prevalence of radial tear (P = 0.021) than those in the conservative group. In the multivariate analysis, RPE remained a relevant independent factor (P = 0.035) for future UKA. An ROC analysis found that the cut-off point of RPE was 33% (sensitivity, 81.2%; specificity, 63.3%).

CONCLUSION

RPE was a predictor of the prognosis of patients who underwent UKA within 1 year after the onset of SONK. Our results suggest that patients with RPE ≥ 33% are at high risk for progression.

Sagittal Inclination Angle of Graft Is Associated With Knee Stability After Anatomic Anterior Cruciate Ligament Reconstruction

PURPOSE

To evaluate whether the sagittal inclination angle (SIA) of a graft is associated with postoperative knee stability after anatomic anterior cruciate ligament (ACL) reconstruction.

METHODS

All patients who had undergone anatomic ACL reconstruction between April 2014 and September 2015 in addition to volunteers with no history of knee injury were eligible for inclusion in this study. The patients were evaluated by magnetic resonance imaging of the knee in full extension at 1 year after surgery, as were volunteers. The posterior tibial slope (PTS) angle and the SIA of the intact ACL and reconstructed graft were measured relative to each medial and lateral tibial plateau. The patients were examined for knee stability by the side-to-side difference in the anterior tibial translation on stress radiographs at minimum 2-year follow-up.

RESULTS

We included 43 patients (26 male, 17 female, mean age 32.8 ± 14.8 years) and 12 volunteers (7 male, 5 female, mean age 28.7 ± 3.1 years) as normal controls. The mean follow-up duration was 29.8 ± 3.6 months. The mean PTS angle and mean SIA in the patients did not significantly differ from those of the intact ACL. The PTS angle in the patients was not significantly correlated with postoperative side-to-side difference in the anterior tibial translation. However, the graft SIA was significantly correlated with the postoperative anterior tibial translation (medial SIA; r = 0.42, P = .005, lateral SIA; r = 0.52, P < .001).

CONCLUSIONS

Even if anatomically reconstructed, the graft SIA in reference to the tibial plateau at full knee extension is variable and is associated with postoperative knee stability. The larger graft SIA was correlated with graft laxity after anatomic ACL reconstruction.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Comparison of Intravenous and Periarticular Administration of Corticosteroids in Total Knee Arthroplasty: A Prospective, Randomized Controlled Study

BACKGROUND

Corticosteroids are widely used in total knee arthroplasty (TKA) to relieve postoperative pain and prevent postoperative nausea. The aim of this prospective, randomized controlled study was to compare the effects of intravenous and periarticular administration of corticosteroids on pain control, prevention of postoperative nausea, and inflammation and thromboembolism markers following TKA.

METHODS

One hundred patients undergoing TKA were randomly allocated to either the intravenous administration or periarticular injection group. The intravenous administration group received 10 mg dexamethasone 1 hour before and 24 hours after the surgical procedure, as well as a periarticular injection placebo during the procedure. The periarticular injection group received a 40-mg injection of triamcinolone acetonide during the surgical procedure, as well as an intravenous administration placebo 1 hour before and 24 hours after the procedure. Postoperative pain scores at rest and during walking and nausea scores were recorded according to the 0-to-10 Numerical Rating Scale. Interleukin-6 (IL-6), C-reactive protein (CRP), and prothrombin fragment 1.2 (PF1.2) were measured preoperatively and postoperatively.

RESULTS

Pain scores at rest and during walking 24 hours postoperatively were significantly lower in the periarticular injection group than in the intravenous administration group. Nausea scores showed no significant difference between groups. IL-6 at 24 and 48 hours postoperatively also showed no significant difference between groups. CRP at 24 and 48 hours postoperatively was significantly lower in the intravenous administration group than in the periarticular injection group. In contrast, CRP at 1 week postoperatively was significantly higher in the intravenous administration group than in the periarticular injection group. The mean PF1.2 was significantly lower in the intravenous administration group than in the periarticular injection group at 4 hours postoperatively. Two cases of deep venous thrombosis in each group were detected with use of ultrasonographic examination.

CONCLUSIONS

Periarticular injection of corticosteroids showed a better pain-control effect at 24 hours postoperatively than did intravenous administration, whereas the antiemetic effect was similar between treatments. Although intravenous administration had a better anti-thromboembolic effect than periarticular injection, the incidence of deep venous thrombosis was low in both groups.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Healing Status of Meniscal Ramp Lesion Affects Anterior Knee Stability After ACL Reconstruction

Background

Although the biomechanical importance of the ramp lesion in the anterior cruciate ligament (ACL)-deficient knee has been demonstrated, there is no clear consensus on the appropriate treatment for ramp lesions during ACL reconstruction.

Purpose

To compare the postoperative outcomes for ramp lesions between patients treated with all-inside repair through the posteromedial portal and those whose ramp lesions were left in situ without repair during ACL reconstruction. We also determined whether ramp lesion healing status affected postoperative knee stability.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 57 patients who underwent anatomic double-bundle ACL reconstruction between August 2011 and December 2017 had attendant ramp lesions. Of these, 25 ramp lesions that were considered stable were left in situ without repair (Nonrepaired group), and 25 ramp lesions, including 21 stable and 4 unstable lesions, were treated using all-inside repair through the posteromedial portal (Repaired group). We evaluated the side-to-side difference (SSD) in anterior tibial translation on stress radiographs and rotational stability by using the pivot-shift test 2 years after surgery, and healing status of the ramp lesions was evaluated on 3.0-T magnetic resonance imaging (MRI) scans 1 year after surgery.

Results

The mean SSDs in anterior translation were 2.4 ± 1.6 mm for the Nonrepaired group and 1.9 ± 1.6 mm for the Repaired group, with no significant differences. The positive ratios on the pivot-shift test were not significantly different between groups. Healing rates of ramp lesions on MRI scans showed a significant difference between the Nonrepaired group (60%) and the Repaired group (100%) (P = .001). The mean SSDs for knees in which the ramp lesion had healed as shown on MRI scans and those in which it had not healed were 1.9 ± 1.6 mm and 3.2 ± 1.1 mm, respectively, which was a significant difference (P = .02).

Conclusion

Healing rates of ramp lesions were significantly better in the Repaired group than in the Nonrepaired group, although postoperative knee stability was not significantly different between groups. Anterior laxity in the knees in which the ramp lesion was unhealed was significantly greater compared with the knees in which the ramp lesion healed. All-inside repair through the posteromedial portal was a reliable surgical procedure to heal ramp lesions.

Younger patients with high varus malalignment of the contralateral knee may be candidates for simultaneous bilateral total knee arthroplasty

PURPOSE

Bilateral total knee arthroplasty (TKA) is being performed more frequently. However, a consensus on whether simultaneous or staged procedures should be performed is not available. This study reviewed the clinical course of contralateral knees in patients who underwent unilateral TKA (UTKA) to determine which patients are candidates for simultaneous bilateral TKA (BTKA).

METHODS

One hundred eighty-six patients with osteoarthritis who underwent UTKA at a single hospital between 2006 and 2009 (follow-up mean, 10.1 years) were retrospectively investigated. Age, sex, obesity, contralateral knee pain, Hospital for Special Surgery score, femorotibial angle (FTA), and Kellgren-Lawrence grades at the time of initial surgery were used to evaluate the risk for requiring contralateral TKA. Survival analysis and receiver-operating characteristic (ROC) analysis were performed.

RESULTS

Ninety-one patients (48.9%) underwent contralateral TKA. The FTA of the contralateral knee (CFTA) was an independent related factor (hazard ratio, 1.15; p < 0.001), and the CFTA cut-off value for the next surgery was 183° (area under the curve, 0.85; sensitivity, 80.7%; specificity, 76.2%). The 10-year Kaplan-Meier survival rates for the CFTA < 183° group and the CFTA ≥ 183° group were 79.1% and 27.0%, respectively. In the CFTA ≥ 183° group, age was the predictor of future TKA, and elderly patients tended to not require a second procedure. The age cut-off value for the next surgery was 76 years.

CONCLUSIONS

Varus deformities in the contralateral knee predicted additional contralateral TKA. Patients with CFTA ≥ 183° and aged 75 years or younger are considered reasonable candidates for simultaneous BTKA.

LEVEL OF EVIDENCE

III.

Factors Associated With Posterior Cruciate Ligament Tightness During Cruciate-Retaining Total Knee Arthroplasty

BACKGROUND

The purpose of our study was to identify factors affecting posterior cruciate ligament (PCL) tightness during cruciate-retaining total knee arthroplasty.

METHODS

A total of 225 varus osteoarthritic knees that underwent cruciate-retaining total knee arthroplasty were included in this study. When the flexion gap was tighter than the extension gap after all bone resection and the lift-off sign was positive during surgery, the PCL was released. The association between PCL release and potential risk factors, such as age, gender, body mass index, preoperative range of motion, anterior cruciate ligament status, preoperative hip-knee-ankle angle (HKA), decrease in posterior condylar offset, and also change in tibial posterior slope angle (TPSA) from preoperative to postoperative measurement, was evaluated by univariate and multivariate logistic regression analyses.

RESULTS

The PCL was released in 68 of 225 knees (30.2%). According to the univariate logistic regression analysis, preoperative knee flexion angle (odds ratio [OR], 0.98), anterior cruciate ligament status (OR, 3.94), the decrease in medial (OR, 0.73) and lateral posterior condylar offset (OR, 0.76), preoperative HKA (OR, 1.1), preoperative (OR, 1.15) and postoperative TPSA (OR, 0.77), and the decrease in TPSA (OR, 1.23) were associated with PCL release. Multivariable stepwise logistic regression analysis demonstrated that preoperative HKA (P < .001), postoperative TPSA (P = .02), and the decrease in TPSA (P < .001) were independently associated with PCL release.

CONCLUSION

Many factors are associated with PCL tightness. The change in TPSA between preoperative and postoperative measurements was a higher risk factor than postoperative TPSA.

Magnetic Resonance Imaging Diagnosis of Medial Meniscal Ramp Lesions in Patients With Anterior Cruciate Ligament Injuries

PURPOSE

To prospectively evaluate the sensitivity and specificity of magnetic resonance imaging (MRI) for diagnosing ramp lesions, to compare them between 1.5- and 3-T MRI, and to evaluate whether bone contusion of the posterior lip of the medial tibial plateau was associated with ramp lesions.

METHODS

For 155 knees that underwent primary ACL reconstruction, we prospectively examined for ramp lesions and medial meniscal body tears on MRI. MRI diagnosis of ramp lesions required high signal irregularity of the capsular margin or separation in the meniscocapsular junction of the medial meniscus posterior horn on sagittal images. Bone contusion of the posterior lip of the medial tibial plateau was verified in 105 knees with MRI performed within 6 weeks after injury. All ramp lesions were identified by transcondylar observation during surgery. The sensitivity and specificity of MRI for ramp lesions and body tears were measured. Furthermore, we evaluated whether bone contusion of the medial tibial plateau was associated with ramp lesions. The χ-square test was used for statistical analysis.

RESULTS

During surgery, ramp lesions were observed in 46 knees and medial meniscal body tears were seen in 35 knees. The sensitivity of MRI for ramp lesions was 71.7% and specificity was 90.5%. The sensitivity for ramp lesions was significantly lower than that for meniscal body tears (94.3%) (P = .01). The sensitivity of 3-T MRI (83.3%) was superior to that of 1.5-T MRI (67.6%), but not significantly different. The incidence of bone contusions was not significantly different among ramp lesions (38.5%), body tears (40.0%), or no tears (30.5%).

CONCLUSIONS

The sensitivity of MRI for diagnosing ramp lesions was significantly lower than that for medial meniscal body tears. Bone contusion of the posterior lip of the medial tibial plateau on MRI was not associated with ramp lesions.

LEVEL OF EVIDENCE

Level III, comparative trial.

Efficacy of β-Tricalcium Phosphate Graft into the Bone Defects after Bone-Patellar Tendon-Bone Anterior Cruciate Ligament Reconstruction

This prospective pilot study investigated whether grafting β-tricalcium phosphate (B-TCP) into the bone-patellar tendon-bone (BPTB)-harvesting site after anterior cruciate ligament reconstruction would accelerate bone and tendon regeneration in the grafted site. Overall, 19 patients agreed prospectively to undergo regular morphological and histological examinations of the B-TCP-grafted site. Postoperative radiographic, ultrasonographic, and magnetic resonance imaging (MRI) examinations were performed to evaluate the grafted site at 1, 3, 6, and 12 months. Postoperative knee function and donor-site morbidity were assessed at 12 months using the kneeling test. A histological examination was also performed at this time Radiographic examination and MRI showed that the grafted B-TCP was completely absorbed and remodeled into normal bone structure in the tibia and patella at 6 months postoperatively. Histological and ultrasonographic examinations of all subjects showed that the grafted B-TCP was substituted by normal bone tissue, and the patellar tendon - bone junction had regenerated at 12 months postoperatively. Clinical functional knee tests showed good recovery of the donor site. All patients could perform kneeling and knee walking on hard ground. The results of this pilot study suggest that grafting B-TCP into the BPTB-harvesting site promotes the remodeling process of the bone and patellar tendon structures. This surgical treatment would decrease an incidence of the anterior knee pain after ACLR using a BPTB autograft.

Thirteen-Week Oral Toxicity Study of l-Glutamine in Rats

l-Glutamine (Gln) is a semiessential amino acid used in enteral feeding in critically ill patients, and is contained in numerous dietary supplements available to the general public. This study evaluated toxicological effects of Gln in male and female Sprague-Dawley rats. Gln produced by Ajinomoto Co. (Tokyo, Japan) was incorporated into a standard diet at doses equal to 1.25%, 2.5%, and 5.0% ( w/ w), respectivelly. A control group of rats received only a standard diet. All diets were administered ad libitum for 13 consecutive weeks. To examine recoverability of any potential effects, the administration period was followed by a 5-week recovery period, during which only the standard diet was provided to all animals. Throughout the administration and recovery periods, no deaths were observed, and no changes in diet consumption, ophthalmologic findings, gross pathology, and histopathology were detected. Several changes in urine parameters (total protein, urine pH, and a positive incidence (±) of ketone bodies) were observed in the 2.5% and 5.0% groups at the end of the administration period. Minor increases were found in hematology parameters for the 5.0% group (platelet count, γ-globulin, lactate dehydrogenase [LDH]), but all changes were within physiological range. No effects of administration were observed in the 1.25% group. The no-observed-adverse-effect level (NOAEL) for Gln was estimated at 1.25% for both genders (males 0.83 ± 0.01 g/kg/day; females, 0.96 ± 0.06 g/kg/day).

Thirteen-Week Oral Toxicity Study of l-Arginine in Rats

The amino acid l-arginine (Arg) has been used extensively in dietary and pharmacological products. This study evaluated toxicological and behavioral effects of Arg produced by Ajinomoto Co. (Tokyo, Japan) during a dosing study with male and female Sprague-Dawley rats. The amino acid was incorporated into a standard diet at doses equal to 1.25%, 2.5%, and 5.0% ( w/w). A control group of rats received only a standard diet. All diets were administered ad libitum for 13 continuous weeks. To examine recoverability of any potential effects, the administration period was followed by a 5-week-long recovery, during which only a standard diet was provided. In male and female rats in each concentration group, treatment-related changes were not observed for clinical signs, body weights, diet consumption, ophthalmology, gross pathology, organ weight, or histopathology. An elevated level of plasma glucose was detected in some male rats (5.0%, w/ w) during the analysis conducted in the fifth week of administration; however, the degree of the change was within the physiological range, and no changes were observed at the end of the administration period. In the same group, an increase in hemoglobin, together with a tendency toward an increase in the red blood cell counts, was found, but the change was considered toxicologically insignificant. The no-observed-adverse-effect level (NOAEL) for Arg was estimated at 5.0% ( w/w) for both genders (males, 3.3 ±0.1 g/kg/day; females, 3.9 ±0.2 g/kg/day).

Thirteen-Week Oral Toxicity Study of Branched-Chain Amino Acids in Rats

Branched-chain amino acids (l-isoleucine, l-valine, and l-leucine) are being increasingly used in sport supplements. This study evaluated toxicological and behavioral effects of l-isoleucine (Ile), l-valine (Val), and l-leucine (Leu) during a dosing study with male and female Sprague-Dawley rats. The amino acids were incorporated into a standard diet at doses equal to 1.25%, 2.5%, and 5.0% ( w/ w). A control group of rats received a standard diet. All diets were administered ad libitum for 13 consecutive weeks. To examine stability of any potential effects, the administration period was followed by a 5-week recovery period, during which only the standard diet was provided to all animals. No significant, dose-related effects on body weight were found in rats fed a Leu-and Ile-supplemented diet. Val mixed into a diet at 5.0% ( w/ w) decreased slightly, but significantly body weight gain in females, but not males. Ile (5.0% w/ w) affected the urine electrolytes, protein, ketone bodies, urine glucose, and urobilinogen in both genders, yet the observed changes remained mostly within the range observed in controls. The random findings in hepatology and ophthalmology at the 13-week sacrifice were not considered toxicologically relevant to effects of the tested amino acids. No significant changes in organ weights were recorded. We estimate the no-observed-adverse-effect level (NOAEL) for Ile at 2.5% for both genders (male, 1.565 ± 0.060 g/kg/day; females, 1.646 ± 0.095 g/kg/day), Val at 5.0% for males (3.225 ± 0.135 g/kg/day) and 2.5% for females (1.853 ± 0.060 g/kg/day), and Leu at 5.0% for both genders (males, 3.333 ± 0.101 g/kg/day: females, 3.835 ± 0.257 g/kg/day).

Tibial Tubercle in Valgus Osteoarthritic Knees Is More Laterally Positioned Than in Varus Knees

BACKGROUND

The tibial tubercle (TT) is the most reliable landmark of the tibial component rotation in total knee arthroplasty. However, there is no report comparing the position of the TT between valgus and varus osteoarthritic knees.

METHODS

Using preoperative computed tomography, we measured the TT-posterior cruciate ligament (PCL) distance representing the degree of lateralization of the TT and the angle between Akagi's anteroposterior (AP) axis and the dorsal condylar line (DCL) of the tibia in 36 valgus and 40 varus osteoarthritic knees and compared them.

RESULTS

The mean TT-PCL distances in valgus and varus knees were 26.1 (18.2-36.8) and 17.2 mm (10.3-22.6), respectively, with a significant difference (P < .001). Twenty-four of 36 valgus knees (67%) had abnormal TT-PCL (>24 mm). The mean AP-DCL angles in valgus and varus knees were 103° (95.8°-114.8°) and 93.2° (85.3°-99.6°), respectively, with a significant difference (P < .001).

CONCLUSION

The TT in valgus knees was significantly more laterally positioned than in varus knees. Also, Akagi's AP axis in valgus knees was significantly more externally rotated relative to the DCL of the tibia than in varus knees. Attention is necessary to correct rotational alignment without posterolateral overhang of the tibial component during total knee arthroplasty, particularly for valgus knees.

Clinical Outcomes After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction: Comparison of Extreme Knee Hyperextension and Normal to Mild Knee Hyperextension

PURPOSE

The aim of this study was to compare postoperative outcomes after anatomic double-bundle anterior cruciate ligament reconstruction (ACLR) in extreme knee hyperextension versus normal to mild knee hyperextension.

METHODS

For 100 patients who underwent anatomic double-bundle ACLR using semitendinosus tendon, we evaluated the side-to-side difference (SSD) in anterior tibial translation (measured on stress radiographs) and rotational stability (assessed by the pivot-shift test) 2 years after surgery. Loss of extension (LOE) was evaluated on lateral radiographs of both knees in full extension, and graft integrity was assessed during second-look arthroscopy 1 to 2 years after surgery. In accordance with the Beighton and Honan criteria, patients with an extension angle less than or equal to 10° in the contralateral uninjured knee composed the group with 10° or less hyperextension (N group), and those with an extension angle of greater than 10° composed the group with more than 10° hyperextension (H group). Postoperative results were compared between these groups.

RESULTS

Mean extension angles in the N and H groups were 5.8° ± 2.9° and 14.7° ± 3.0°, respectively. The mean SSD in anterior translation was 2.2 ± 2.9 mm for the N group and 2.8 ± 2.9 mm for the H group, with no significant difference. The positive ratios on the pivot-shift test were not significantly different between the groups. Mean LOE in the N and H groups was -0.7° ± 3.7° and 1.3° ± 3.3°, respectively, with a significant difference (P = .007). During second-look arthroscopy, 6 of 58 knees in the N group and 13 of 42 knees in the H group had superficial graft laceration of the anteromedial bundle graft, with a significant difference (P = .01) seen between groups.

CONCLUSIONS

Anatomic double-bundle ACLR for extreme knee hyperextension may attain the same postoperative anterior and rotational stability as seen in knees with normal to mild hyperextension. However, it increased superficial graft laceration.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The importance of tibial tunnel placement in anatomic double-bundle anterior cruciate ligament reconstruction

PURPOSE

The purposes of this study were to measure the anterior edge of the tibial tunnel after anatomic anterior cruciate ligament (ACL) reconstruction on lateral radiographs and to determine whether the difference in tibial tunnel placement affects postoperative outcomes.

METHODS

For 60 patients who underwent anatomic double-bundle ACL reconstruction with semitendinosus tendon, we evaluated the side-to-side difference in anterior tibial translation on stress radiographs, as well as rotational stability by the pivot-shift test, 2 years after surgery. Loss of extension (LOE) was evaluated on lateral radiographs of both knees in full extension, and graft integrity was assessed during second-look arthroscopy 1 to 2 years after surgery. On true lateral radiographs, we measured the anterior placement percentage of the tibial tunnel using the method described by Amis and Jakob. The cutoff value was set at 25% of the mean value of the anterior edge of the ACL that Amis and Jakob reported, and patients were divided into 2 groups (27 in the anterior group and 33 in the posterior group). Postoperative clinical results were compared between the groups.

RESULTS

The mean anterior placement percentage was 26.0% ± 4.1%. The postoperative mean side-to-side difference was 1.4 ± 2.7 mm for the anterior group and 3.0 ± 2.7 mm for the posterior group, a significant difference (P < .05). The positive ratio of the pivot-shift test was not significantly different between groups (P > .05). Mean LOE in the anterior and posterior groups was 0.9° ± 3.0° and -0.8° ± 4.0°, respectively; the difference was not significant (P > .05). Five of 27 knees in the anterior group and 5 of 33 knees in the posterior group had superficial graft laceration or elongation, which was not significantly different (P > .05).

CONCLUSIONS

Anterior placement of the tibial tunnel in anatomic double-bundle ACL reconstruction leads to better anterior knee stability than posterior placement does. Anterior tibial tunnel placement inside the footprint did not increase the incidence of LOE and graft failure.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Histologic analysis of postmeniscectomy osteonecrosis

Bone marrow signal changes on magnetic resonance imaging (MRI) after meniscectomy have been reported as evidence of postmeniscectomy osteonecrosis, but this pathology is unclear. We conducted a study to follow-up cases with bone marrow signal changes on MRI after meniscectomy and investigate the pathology of underlying lesions. Of 136 patients with no presurgical evidence of osteonecrosis, 29 had juxta-articular bone marrow signal changes on MRI after arthroscopic meniscectomy and subsequently underwent conservative therapy. In 6 of these 29 patients, clinical symptoms and radiographic changes began deteriorating. Based on the Koshino classification, 4 of the 6 patients had Stage-2 knee osteonecrosis and 2 had Stage-3. Arthroscopic and pathologic examinations were performed. Arthroscopic findings were fibrillation (all 6 cases), fissuring (4), ulceration (2), and eburnation (2). Histologic analysis confirmed subchondral bone fractures in all 6 cases, but osteonecrotic lesions were detected only in 2 cases with obvious radiologic deterioration. Postmeniscectomy osteonecrosis might result from subchondral bone fractures. Fracture healing is worse in patients with comorbidities than in those without it; comorbidities might be a risk factor for osteonecrosis.

Serum alkaline phosphatase isoenzymes in laboratory beagle dogs detected by polyacrylamide-gel disk electrophoresis

Serum alkaline phosphatase (ALP) activity is frequently measured in toxicity studies. Itoh et al. (2002) reported that a commercially available polyacrylamide-gel (PAG) disk electrophoresis kit used in humans (AlkPhor System, Jokoh Co., Ltd., Tokyo, Japan) for identifying serum ALP isoenzymes was useful for veterinary clinicopathological diagnosis in mongrel dogs. In the present study, based on the report of Itoh et al. (2002), we tried to expand the application range of this kit to laboratory beagle dogs which are commonly used in toxicity studies. In order to identify the origin of each ALP isoenzyme, tissue ALP extracts from the liver, bone and small intestine and serum samples were treated with neuraminidase, anti-small intestinal ALP antibody, ALP inhibitor levamisole and/or wheat germ agglutinin (WGA). The main serum ALP isoenzymes in 5-month-old intact beagle dogs were bone-derived (bone and atypical ALP: corresponding to human variant bone ALP) and they tended to decrease with age. However, liver-derived ALP isoenzyme greatly increased in the serum of cholestasis model dogs. The cholestasis model dogs also had a large molecular ALP detected in the resolving gel. This ALP could be originated from intestinal ALP or corticosteroid-induced ALP (CALP), because the activity remained even after levamisole inhibition. CALP was observed in intact laboratory beagle dogs with individual differences. These results suggest that the present method is a useful tool for detecting serum ALP isoenzymes in laboratory beagle dogs and concomitant levamisole inhibition with another gel is applicable for the evaluation of organ toxicity.