Moon Jong Chang

The MRI findings of meniscal root tear of the medial meniscus: emphasis on coronal, sagittal and axial images

PurposeThe purpose of this study was to evaluate the accuracy of the characteristic magnetic resonance imaging (MRI) findings of medial meniscal root tear in the coronal, sagittal and axial planes.MethodsThirty arthroscopically diagnosed patients who had undergone preoperative knee MRI were included in this study. They were compared to 30 age-matched patients with medial meniscus tears without root tears. The findings used for imaging analysis were as follows: the radial tear on the meniscal root of the medial meniscus in the axial plane, the presence of the truncation sign in the coronal plane and the ghost meniscus sign in the sagittal plane. Meniscal extrusion in the coronal plane was also evaluated. All the MRI findings of both groups were statistically analyzed.ResultsAll the findings were more frequently found in the root tear group than those in the control group (Pxa0<xa00.05). The sensitivity, specificity, positive predictive value and negative predictive value of finding a radial tear in the axial plane were 93.3, 100, 100 and 93.8%, respectively. In the coronal plane, rates for the presence of the truncation sign were 90, 100, 100 and 90.9%, respectively. In the sagittal plane, rates for the presence of the ghost meniscus sign were 96.7, 96.7, 96.7 and 96.7%, respectively. The rates for the meniscus extrusion in the coronal plane were 63.3, 90, 86.4 and 71.1%, respectively.ConclusionsThe findings of medial meniscal root tear were characteristic as compared with the control group. Radial tear in the axial plane also showed similar diagnostic accuracy as that seen in the other planes. The characteristic findings provide high diagnostic accuracy, and axial plane is helpful to detect medial meniscal root tear.Level of evidenceDiagnostic study, Level III.

Symptomatic torn discoid lateral meniscus in adults

The purposes of this study were to report degenerative changes that coexist with a symptomatic torn discoid lateral meniscus in adults and to analyze the factors associated with the accompanied degenerative changes. From 1997 to 2008, 329 knees in the 305 patients were included. Associations between the status of the meniscus and the coexisting degenerative changes on the images and the arthroscopic findings were statistically analyzed. Marginal osteophyte was seen on conventional radiography in 118 patients (36%). Ninety patients (27%) had arthroscopically confirmed chondral lesion. Age, duration of symptoms, the type of meniscus, the type of tear and the magnetic resonance image classification were associated with the formation of the marginal osteophyte and chondral lesion on univariate analysis (Pxa0<xa00.05). After conducting multivariate analysis, the type of tear and magnetic resonance image classification had a statistically significant association with the severity of marginal osteophyte and chondral lesion (Pxa0<xa00.05).

Correlation between dynamic postural stability and muscle strength, anterior instability, and knee scale in anterior cruciate ligament deficient knees

AimThe purpose of this study was to assess the correlations between dynamic postural stability and muscle strength, anterior instability, and knee scores in anterior cruciate ligament (ACL) deficient knees.MethodWe examined 40 male patients with ACL injury prior to surgery. Maximal torques of flexors and extensors of the injured knee at 60 and 180°/s were evaluated using an isokinetic testing device. Anterior translations of the tibia were measured using a KT-2000 arthrometer, and dynamic postural stabilities were measured during single-leg stance using the Biodex Stability System (BSS). Knee statuses were evaluated using Lysholm and International Knee Documentation Committee (IKDC) knee scores. Correlations between dynamic postural stability and muscle strength, anterior instability, and knee scores were determined.ResultsSignificant correlations were found between maximal torques of the extensor of injured knees at 60 and 180°/s (rxa0=xa0−0.52, pxa0=xa00.048 and rxa0=xa0−0.46, pxa0=xa00.019, respectively) and dynamic postural stability, and maximal torques of flexors of injured knees showed similar relations (rxa0=xa0−0.51, pxa0=xa00.0048 and rxa0=xa0−0.47, pxa0=xa00.016, respectively). Lysholm and IKDC knee scores were also found to be correlated with dynamic postural stability (rxa0=xa0−0.49, pxa0=xa00.001 and rxa0=xa0−0.52, pxa0=xa00.005, respectively). However, no correlation was found between grade of anterior translation measured using the KT-2000 arthrometer and dynamic postural stability (pxa0=xa01.0).ConclusionDynamic postural stability determined using the BSS appears to be influenced by muscle strength, as determined by isokinetic testing, but not with grade of anterior translation measured using a KT-2000 arthrometer. Subjective knee scores appear to improve in parallel with dynamic postural stability.

Non-operative treatment of ACL rupture with mild instability

PurposeThis study examined whether or not conservative treatment of an acutely injured anterior cruciate ligament (ACL) could be successful in a select group of patients. Routine ACL reconstruction surgery in all acute ACL-injured patients should be avoided. We hypothesize that acutely injured ACL with mild instability at the initial physical examination could be improved even if there is disruption of ACL fibers on magnetic resonance images (MRI).Materials and methodsAmong 232 acute ACL-injured patients who visited our institution from March 1997 to April 2006, 48 were treated non-operatively. Patients diagnosed with an acute ACL injury by MRI with Lachman test ≤grade 1 were treated non-operatively. In this study, 30 male and 18 female patients with a mean age of 31.8xa0years were enrolled. The initial and follow-up Lachman test and pivot shift test were performed 3xa0weeks after the injury. The Lysholm knee scoring scale, International Knee Documentation Committee (IKDC) score and KT-2000 were obtained at the last follow-up.ResultsThere were 12 complete (25%) and 36 incomplete ACL ruptures (75%). The patients were followed up clinically and with MRI for 21.5 and 11.3xa0months, respectively. The follow-up Lachman test improved to grade 0 in 41 patients (87%). Thirty-six patients (76%) showed no laxity in the follow-up pivot shift test. The last follow-up IKDC score was a mean value of 91.1 points. KT 2000 was performed in 40 patients with a mean side-to-side difference of 2.85xa0mm. Of 48 patients, 46 showed restored ACL continuity and 39 (84%) showed restored low signal intensity on MRI.ConclusionA selective group of ACL tears with mild instability (Lachman ≤grade 1), though these seem to be complete tears on MRI, can show restoration of their continuity and signals on the MRI. Joint laxity on physical examination was improved at follow-up. These results suggest that a select group of patients with an acute ACL injury can successfully undergo non-operative treatment. In addition, unnecessary early ACL reconstruction surgery should be avoided.

Localized tenosynovial giant cell tumor in both knee joints

Tenosynovial giant cell tumor, previously called pigmented villonodular synovitis (PVNS), is a rare benign neoplastic process that may involve the synovium of the joint. The disorder is usually monoarticular and only a few cases have been reported on polyarticular involvement. Herein, we present a case of localized intra-articular tenosynovial giant cell tumor in a 29-year-old man involving both knee joints with a description of the MR imaging and histological findings.

Infrapatellar fat pad preservation reduces wound complications after minimally invasive total knee arthroplasty

IntroductionThe aim of this study was to determine whether pain intensity and wound complication rates differ between patients with and without preservation of the infrapatellar fat pad (IPFP) after minimally invasive total knee arthroplasty (TKA). The authors also sought to determine whether IPFP preservation affects operation time.Materials and methodsThis retrospective study included 448 knees with primary TKA. The IPFP was totally resected in 201 knees (IPFP-R group), and was preserved in 247 knees (IPFP-P group). Pain score was determined using the visual analog scale during the first 72xa0h after surgery. Wound complication rates and operation times were also evaluated. A wound complication was defined as persistent wound drainage for three or more days after surgery.ResultsThere was no difference in pain levels between the two groups. However, there were fewer wound complications in the IPFP-P group (3xa0%) than in the IPFP-R group (13xa0%). The operation time was longer in the IPFP-P group than in the IPFP-R group (70 vs. 64xa0min, respectively).ConclusionsAlthough IPFP preservation delayed operation time, it decreased wound complications after MIS TKA. These findings are important to consider when deciding whether or not to resect the IPFP. Whenever possible, IPFP preservation is probably the preferred technique to reduce wound complications.

Minimum five-year follow-up results of single-radius, high-flex posterior-stabilized TKA.

We studied 75 primary total knee arthroplasties (TKAs) performed using a single-radius, high-flex posterior-stabilized insert design with a minimum 5-year follow-up to document its implant specific complications and clinical results. Nonprogressive osteolysis was observed at zone 4 of the femoral component in 6 knees (8%) and at zone 1 of the tibial component in 6 knees (8%). However, no complications associated with high flexion designs, such as early aseptic loosening, were observed.Preoperatively, mean Knee Society Knee Score and Knee Society Function Score were 55.1 and 45.5, respectively (range, 10-83 and 20-80, respectively). At last follow-up, mean Knee Society Knee Score and Knee Society Function Score improved to 94.9 and 85.9, respectively (range, 70-100 [P<.0001] and 45-100 [P<.0001], respectively). Mean maximal flexion was 122.1 degrees (range, 90 degrees -140 degrees ) and mean range of motion (ROM) was 110.3 degrees (range, 80 degrees -135 degrees ) preoperatively, and these values improved to 128.9 degrees (range, 110 degrees -150 degrees [P<.0001]) and 127.8 degrees (range, 110 degrees -150 degrees [P<.0001]), respectively, at last follow-up. Preoperative ROM was found to be the only factor significantly correlated with postoperative ROM at last follow-up by univariate (P=.0020) and multivariate analysis (P<.0067). Accordingly, clinical results were comparable to previous reports of high-flex implants without implant-specific complications.

Post-tibial cyst formation over 2 years after posterior cruciate ligament reconstruction

We report a case of an asymptomatic post-tibial cyst with direct communication to the posterior orifice of the tibial tunnel after a posterior cruciate ligament (PCL) reconstruction. Two years earlier, the patient had undergone a PCL reconstruction using a transtibial technique through a lateral tibial tunnel and with a 10-mm bio-absorbable interference screw fixation. Magnetic resonance imaging (MRI) was taken with patient’s consent when the patient re-visited our hospital to remove the metal post-tie screw. The patient was satisfied with the result and the cyst was an incidental finding. This complication appeared to be a consequence of direct communication between the joint and the post-tibial tunnel through the posterior orifice of the tibial tunnel because of the failed osteointegration of the graft. To our knowledge, this is the first report of cyst formation at the post-tibial tunnel after a PCL reconstruction.

Soft tissue laxity should be considered to achieve a constant polyethylene thickness during total knee arthroplasty

IntroductionIn total knee arthroplasty (TKA), the gap expansion effect by soft tissue laxity and bone resection amount influence directly on the proper gap size and ideal polyethylene insert thickness. In this study, we hypothesized if bone resection level could be controlled lesser as gap expansion effect resulted in the effects on gap expansion of the collateral release and lax lateral structure, appropriate gap size would be attained without extensive medial soft tissue release even in severe varus deformed knee. The purpose of this study was to show the usefulness of preoperative calculation of soft tissue laxity for determining the appropriate gap size for the targeted PE thickness in TKA.MethodsThe preoperative varus stress view was used to estimate the effect of soft tissue release on extension gap expansion after primary bone resection. The amount of bone resection was determined with a parallel bone resection device used in our institution. Lateral laxity amount was applied into the device. This study was a retrospective review of 850 TKAs [451 with <10º varus deformity of the mechanical femoro-tibial angle (group 1); 399 with ≥10º varus deformity (group 2)] with a minimum follow-up of 1xa0year. We compared the range of motion (ROM), the knee society score (KSS), and the incidence of surgical complications at postoperative 1xa0year between the two groups.ResultsThe mean PE thickness was 10.8xa0±xa01.1 in group 1 and 10.9xa0±xa01.1 in group 2. The proportion of patients with appropriate PE thickness (i.e., 10–12xa0mm) was 97.6xa0% in group 1 and 97.2xa0% in group 2. The ROM and KSS did not differ significantly between groups.ConclusionThis study showed the usefulness of preoperative calculation of soft tissue laxity for appropriate gap size for targeted polyethylene thickness and possibility to attain constant extension gap regardless of preoperative varus deformity.

Disparate Postoperative Results in the First and Second Knees on Simultaneous Bilateral Total Knee Arthroplasty

We hypothesized that the circumstances of the two consecutive operations of a simultaneous bilateral total knee arthroplasty (TKA) are different, and could lead to different outcomes of overlapping bilateral TKAs. Both knees of 420 subjects were evaluated in the current study. In the second TKA, there were more incidence rates of outlier in mechanical femoro-tibial angle (16.2% vs. 9.0%), more blood loss (735 vs. 656 mL), and longer operation time (61, 58 minutes respectively), as compared to the first TKA, while no significant differences in clinical outcomes. In conclusion, there were no significant differences in the clinical outcomes even though few distinct outcomes due to different circumstances of the surgery. Awareness of these findings can help the continued success of bilateral TKA in an increasing patient population.