Volumetric assessment of extrusion in medial meniscus posterior root tears through semi-automatic segmentation on 3-tesla magnetic resonance images.

BACKGROUND: Many reports have described the relationship between medial meniscus posterior root tears (MMPRTs) and meniscal extrusion on coronal magnetic resonance (MR) images. However, volumetric assessment of meniscal extrusion has not been performed, and the correlation between extrusion length and volume remains unclear. HYPOTHESIS: Extrusion in both length and volume would be greater in MMPRTs than that in the normal medial meniscus, and the extrusion length measured on coronal MR images would be correlated with the extrusion volume. PATIENTS AND METHODS: A total of 20 knees who underwent isolated MMPRTs without trauma history were included in the MMPRT group, and another 20 knees with normal medial meniscus were selected as the control group. All 40 knees underwent 3-tesla MR imaging. The extrusion length of the medial meniscus was measured using coronal MR images only. Volumetric assessments of the meniscus were performed and analyzed via a semi-automatic segmentation. Group-wise comparisons of the extrusion length and volumetric values were conducted, and the correlation between the two measures in both groups was evaluated. RESULTS: The mean extrusion length of the medial meniscus in the MMPRT group was significantly longer (2.60 vs. 0.63mm; p<0.001) than that in the control group. The mean extrusion volume was also significantly higher in the MMPRT than that in the control group (770.93 vs. 193.80 mm3; p<0.001). The extrusion length was significantly and positively correlated with the extrusion volume in both groups (R=0.64; p=0.002 in MMPRT, R=0.73; p<0.001 in the control group). DISCUSSION: Semi-automatic segmentation was used to measure the volume of meniscal extrusion, which had previously only been estimated indirectly with the extrusion length on coronal MR images. MMPRTs significantly increased the extrusion in both measures. The extrusion length measured on coronal MR images was positively correlated with the extrusion volume in both groups. LEVEL OF EVIDENCE: III, Case-control study.

Partial meniscectomy provides the favorable outcomes for symptomatic medial meniscus tear with an intact posterior root.

PURPOSE: This study aimed to investigate the long-term outcomes of arthroscopic partial meniscectomy for medial meniscus tear (with intact posterior root) and to analyze the risk factors for treatment failure. METHODS: The records of 165 patients who underwent partial meniscectomy for medial meniscus tear with intact posterior root with a minimum 5-year follow-up were included. Modified Lysholm score and radiologic outcomes were compared between preoperative and latest follow-up periods. The cumulative Outerbridge grade of the medial compartment was defined as follows: 0-4, low chondral wear; 5-6, intermediate wear; or 7-8, high wear. Kaplan-Meier survival and Cox hazard regression analyses were performed to assess the survivorship after partial meniscectomy. Conversion to total knee replacement arthroplasty, high tibial osteotomy or a Lysholm score of < 65 points indicated treatment failure. RESULTS: Mean Lysholm score improved from 66.3 ± 14.2 preoperatively to 81.8 ± 17.9 at the latest follow-up (p = 0.001). The postoperative 10-year survival rate of the low chondral wear group [97% (95% confidence interval (CI) 141.7-152.6 months)] was higher than that of the intermediate [83.1% (95% CI 129.6-147.9 months)] and high wear groups [76.1% (95% CI 115.2-135.0 months)]. A 1 mm joint space width narrowing led to a 37.7% increase in the failure rate [B = - 0.473; hazard ratio, 0.623 (95% CI 0.423-0.917); p = 0.016]. The high chondral wear group showed a higher failure rate compared to the low wear group [B = 1.870; hazard ratio, 6.488 (95% CI 0.853-49.333); p = 0.041]. CONCLUSION: Partial meniscectomy offers pain relief and functional improvement for medial meniscus tear with intact posterior root. Preoperative joint space narrowing and higher chondral wear at surgery were significant risk factors of treatment failure. Partial meniscectomy should be considered as an effective treatment for irreparable medial meniscus tear with intact posterior root without joint space narrowing and chondral wear. LEVEL OF EVIDENCE: Case series, Level IV.

Discoid lateral meniscus: a simple horizontal tear was associated with less articular cartilage degeneration compared to other types of tear.

PURPOSE: The relationship between the tear type of discoid lateral meniscus (DLM) and articular cartilage degeneration has not been well studied. METHODS: Data from patients with DLM tears who underwent arthroscopic surgery, between 2008 and 2016, were reviewed retrospectively. Demographic variables were obtained from medical records. The types of DLM and meniscal tear and status of cartilage were assessed using operation records and arthroscopic images. Patients were assigned to horizontal or non-horizontal tear groups according to the types of the tear. Factors affecting cartilage degeneration of the lateral femoral condyle (LFC) and lateral tibial plateau (LTP) were identified using logistic regression analysis. The horizontal tear group was divided into two subgroups on the basis of the median value of duration of symptoms and difference in cartilage degeneration between the two subgroups was evaluated. RESULTS: Overall, 355 knees were enrolled and assigned to the horizontal (n = 53) or the non-horizontal (n = 302) tear groups. The incidence of International Cartilage Repair Society grades 2-4 cartilage lesions of the LFC (0%, P < 0.001) and LTP (24.5%, P < 0.001) was significantly lower in the horizontal tear group than in the non-horizontal tear group. Horizontal tear [LFC, odds ratio (OR) = 0.02, P < 0.001; LTP, OR = 0.27, P < 0.001] and age (LFC, OR = 1.04, P < 0.001; LTP, OR = 1.03, P < 0.001) were significantly related to cartilage status. There was no difference in cartilage degeneration between the two subgroups in the horizontal tear group. CONCLUSIONS: A simple horizontal tear was associated with less articular cartilage degeneration compared to other types of tear in the DLM. In the case of simple horizontal tear, there was no difference in the degree of cartilage degeneration according to the duration of symptoms. Therefore, it is not necessary to perform surgical treatment promptly in cases of simple horizontal tears unless the patient's symptoms are severe. LEVEL OF EVIDENCE: III, Case-Control Study.

A Novel Arthroscopic Classification of Degenerative Medial Meniscus Posterior Root Tears Based on the Tear Gap.

BACKGROUND: Degenerative medial meniscus posterior root tears (MMPRTs) are reportedly associated with medial compartment osteoarthritis and meniscal extrusion with a displaced gap from the root insertion. However, degenerative MMPRTs have not yet been clearly classified according to arthroscopic findings. PURPOSE: To classify degenerative MMPRTs according to the tear gap and to investigate how the classification could reflect the joint condition properly. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients who underwent arthroscopic surgery, performed by a single orthopaedic surgeon, for degenerative MMPRTs between August 2006 and February 2017 were included. MMPRTs were classified according to tear patterns observed during arthroscopic surgery (type 1, incomplete root tear; types 2-5, complete root tears), with each type further divided by the size of the tear gap, defined as the degree of tear displacement from the root (type 2, no gap or overlapped; type 3, gap of 1-3 mm; type 4, gap of 4-6 mm; type 5, gap of ≥7 mm). We compared preoperative factors, including the Kellgren-Lawrence (K-L) grade, absolute extrusion, relative percentage of extrusion (RPE), tear gap on magnetic resonance imaging (MRI), and mechanical alignment, as well as intraoperative factors, including chondral wear at surgery, between each MMPRT type. RESULTS: A total of 116 root tears were categorized according to this classification: type 1, 16.4% (19 knees); type 2, 9.5% (11 knees); type 3, 40.5% (47 knees); type 4, 25.0% (29 knees); and type 5, 8.6% (10 knees). Chondral wear of the medial femoral condyle (MFC) (P = .001), K-L grade (P = .001), meniscal extrusion (P = .001), and tear gap on MRI (P = .001) showed a tendency to increase with a higher tear type. Chondral wear (ρ for MFC = 0.388; ρ for MTP = 0.311), K-L grade (ρ = 0.390), and meniscal extrusion (ρ for absolute extrusion = 0.500; ρ for RPE = 0.451) showed a moderate correlation with tear type, whereas tear gap on MRI (ρ = 0.907) showed a strong correlation with tear type. CONCLUSION: Our study introduces a new classification based on the tear gap that can concisely describe a degenerative MMPRT. The classification system demonstrated that a higher tear type (increasing displacement of the tear gap in arthroscopic surgery) is associated with higher meniscal extrusion, severe chondral wear, and greater severity of arthritis.

Accuracy of the femoral tunnel position in robot-assisted anterior cruciate ligament reconstruction using a magnetic resonance imaging-based navigation system: A preliminary report.

BACKGROUND: Tunnel misplacement is a common cause of failed anterior cruciate ligament (ACL) reconstruction. In this study, the accuracy of the femoral tunnel position was evaluated in robot-assisted ACL reconstruction using a magnetic resonance imaging (MRI)-based navigation system. We hypothesized that a difference of less than 2 mm between the planned femoral tunnel position and the created one was achievable. METHODS: Four cadaveric knees underwent robot-assisted ACL reconstruction. A 3-dimensional model using pre-operative MRI images was used for preoperative planning, and a computed tomography (CT) scan was performed postoperatively. The planned and the created femoral tunnels were compared to assess the accuracy of the femoral tunnel position. RESULTS: The distance between the intra-articular points of the planned and the created tunnels was 7.78 mm in the first experiment and 1.47 mm in the last one. The difference in tunnel length was 4.62 mm in the first experiment and 0.99 mm in the last one. CONCLUSIONS: Accuracy of the femoral tunnel position improved with each robot-assisted ACL reconstruction using an MRI-based navigation system. In the last experiment, the accuracy of the femoral tunnel position was satisfactory.

Total Knee Arthroplasty With Patellar Retention: The Severity of Patellofemoral Osteoarthritis Did Not Affect the Clinical and Radiographic Outcomes.

BACKGROUND: The purpose of this study is to compare the clinical and radiographic outcomes of total knee arthroplasty (TKA) with patellar retention in accordance with the severity of patellofemoral arthritis. METHODS: We retrospectively reviewed patients who underwent TKA with patellar retention using the NexGen LPS or LPS-flex system between September 2010 and May 2015. The radiographic severity of patellofemoral arthritis was categorized according to the Iwano classification system, and subjects were divided into mild (stage 0-I) and moderate to severe (stage II-IV) groups. Clinical outcomes were evaluated using the Hospital for Special Surgery score, Knee Society Score, function score, Western Ontario and McMaster Universities Osteoarthritis Index, and Feller score. Radiographic outcomes were assessed using the congruence angle, patellar tilt angle, and lateral patellar displacement. The minimum follow-up for clinical and radiographic evaluation was 2 years. Clinical and radiographic outcomes were compared between the 2 groups preoperatively and at the time of the last follow-up. RESULTS: Four hundred seventy-four knees were enrolled and assigned to mild (n = 208) or moderate to severe (n = 266) groups. The preoperative Feller score was significantly lower in the moderate to severe group (P = .030), whereas the postoperative clinical and radiographic results did not differ significantly between the 2 groups. CONCLUSION: Clinical and radiographic outcomes did not differ in accordance with the severity of patellofemoral arthritis after a minimum 2 years of follow-up of patients treated with TKA with patellar retention. Good outcomes were obtained with patellar retention in TKA, even in patients with advanced patellofemoral osteoarthritis.

Mobile-bearing unicompartmental knee arthroplasty in old-aged patients demonstrates superior short-term clinical outcomes to open-wedge high tibial osteotomy in middle-aged patients with advanced isolated medial osteoarthritis.

PURPOSE: The aim of the present study was to compare the clinical outcomes of mobile-bearing unicompartmental knee arthroplasty (MB-UKA) and open-wedge high tibial osteotomy (OWHTO) for advanced isolated medial osteoarthritis (OA). METHODS: Patients with advanced medial compartment OA (Ahlbäck grade ≥ II) who underwent either MB-UKA with Oxford Knee or OWHTO were included. The minimum follow-up was two years. Clinical outcomes were evaluated using the Hospital for Special Surgery (HSS) score, knee score (KS), and function score (FS) of the Knee Society Knee Scoring System. Pre-operative and post-operative values were compared within groups. Pre-operative and post-operative values and the degree of change were compared between the two groups. Radiologic progression of OA in either the lateral or patellofemoral compartment was evaluated. RESULTS: Forty knees (20 received MB-UKA, 20 received OWHTO) were enrolled. The mean age was higher in the MB-UKA group (67.9 ± 9.0 years) than in the OWHTO group (58.4 ± 5.5 years). The HSS score, KS, and FS were significantly increased post-operatively in both groups. The preoperative HSS score, KS, and FS were significantly lower in the MB-UKA than in the OWHTO group; however, only the post-operative HSS score was significantly higher in the MB-UKA group. The changes in HSS score and KS were also greater in the MB-UKA group. There was no significant difference in OA progression. CONCLUSIONS: Although there was an age difference between the two groups, MB-UKA demonstrated superior short-term clinical outcomes to OWHTO for advanced isolated medial OA. In particular, MB-UKA was more effective in terms of pain relief.

Musicians' medicine: musculoskeletal problems in string players.

There is increasing attention to medical problems of musicians. Many studies find a high prevalence of work-related musculoskeletal disorders in musicians, ranging from 73.4% to 87.7%, and string players have the highest prevalence of musculoskeletal problems. This paper examines the various positions and movements of the upper extremities in string players: 1) basic postures for holding instruments, 2) movements of left upper extremity: fingering, forearm posture, high position and vibrato, 3) movements of right upper extremity: bowing, bow angles, pizzicato and other bowing techniques. These isotonic and isometric movements can lead to musculoskeletal problems in musicians. We reviewed orthopedic disorders that are specific to string players: overuse syndrome, muscle-tendon syndrome, focal dystonia, hypermobility syndrome, and compressive neuropathy. Symptoms, interrelationships with musical performances, diagnosis and treatment of these problems were then discussed.

Morphologic changes in fresh-frozen meniscus allografts over 1 year: a prospective magnetic resonance imaging study on the width and thickness of transplants.

BACKGROUND: Little is known about morphologic changes in the remodeling period after human meniscal allograft transplantation (MAT). HYPOTHESIS: The gross structure of meniscal transplants may be altered significantly in width and thickness during early remodeling periods. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Thirty-one patients who underwent MAT (9 medial and 22 lateral menisci) between 2008 and 2009 were prospectively evaluated by serial magnetic resonance imaging scans 2 days, 6 weeks, and 3, 6, and 12 months after surgery. At each time point, the width and thickness of the menisci were measured. The relative degree of shrinkage after 1 year was categorized as minimal (<10%), mild (10%-25%), moderate (25%-50%), or severe (>50%). The Lysholm score and Tegner activity level were used for clinical outcome scales. RESULTS: More apparent changes were observed at mid-body rather than at the posterior horn. Meniscal width at the mid-body decreased to 89% (P < .01), whereas thickness increased to 115% (P < .01) at 12 months. Shrinkage was observed for 3 months after MAT, but there were no significant changes thereafter. The thickness of the meniscal peripheral rim did not change before 3 months but increased afterward, for up to 1 year. Of the 31 patients, 20 (64.5%) had minimal shrinkage, 6 (19.4%) had mild shrinkage, 5 (16.1%) had moderate shrinkage, and none had severe shrinkage over 1 year. In the 5 cases of moderate shrinkage, the reduction occurred progressively for 1 year. However, the relative morphologic changes did not correlate with clinical outcome scales at postoperative 1 and 2 years (P > .05). The preoperative alignment deviation, cartilage status (Outerbridge grade), age, gender, amount of extrusion, and time from previous meniscectomy did not affect the degree of shrinkage. CONCLUSION: Gross morphologic alterations, as determined by width and thickness, were observed during the first postoperative year. Substantial shrinkage at the mid-body occurred progressively for 1 year in 16.1% of the cases. No association was found between morphologic changes and short-term clinical outcomes.