Relationship between cement penetration and incidence of a radiolucent line around the tibia 2 years after total knee arthroplasty: A retrospective study.

OBJECTIVES: Cement penetration (CP) plays a key role in implant stability for cemented total knee arthroplasty (TKA), and the radiolucent line (RLL) >2 â€‹mm is a preliminary sign for loosening of components. However, the direct relationship between CP and the frequency of RLL >2 â€‹mm is unclear, and the best cut-off value for CP to prevent RLL >2 â€‹mm also remains unclear. This study aimed to investigate this relationship between CP and RLL and to determine the clinical cut-off value for tibial CP in patients 2 years after TKA. METHODS: This retrospective study investigated 157 knees from 123 patients with osteoarthritis who underwent cemented TKA. The CP and RLL immediately after TKA and the RLL 2 years after TKA were measured for the medial, lateral, anterior, and posterior tibial baseplate zones. Receiver operating characteristic (ROC) curves were constructed to determine the best cut-off values for CP. RESULTS: RLL >2 â€‹mm was not observed just after TKA. An RLL >2 â€‹mm was observed in any tibial baseplate zone in 22 knees from 20 patients (RLL+ group) and was not observed in the remaining (RLL- group) 2 years after TKA. The mean CP for all zones was significantly higher in the RLL- group (2.5 â€‹± â€‹1.1 â€‹mm) than in the RLL+ group (1.7 â€‹± â€‹0.6 â€‹mm; P â€‹< â€‹0.001). An RLL >2 â€‹mm was seen in 21 knees in the medial zone, 9 knees in the lateral zone, 8 knees in the anterior zone, and 3 knees in the posterior zone. CP values with RLL >2 â€‹mm were significantly lower than those without the RLL at the medial, anterior, and posterior tibial baseplate zones. The best cut-off values from the ROC curve of CP in each zone were between 1.1 â€‹mm and 2.1 â€‹mm. CONCLUSIONS: The depth of the CP directly affects the incidence of an RLL >2 â€‹mm. The best cut-off value for tibial CP to prevent an RLL >2 â€‹mm is 2.1 â€‹mm.

Characteristics of subscapularis muscle strain in professional baseball players: a case series.

BACKGROUND: Subscapularis muscle strains can develop in professional baseball players, rendering the players unable to continue playing for a certain period. However, the characteristics of this injury are not well known. The purpose of the present study was to investigate the details of the injury and the postinjury course of subscapularis muscle strain in professional baseball players. METHODS: Of 191 players (83 fielders and 108 pitchers) who were members of a single Japanese professional baseball team between January 2013 and December 2022, 8 players (4.2%) had subscapularis muscle strain and were enrolled in this study. The diagnosis of muscle strain was made on the basis of shoulder pain and magnetic resonance imaging findings. The incidence of subscapularis muscle strain, the details of the site of the injury, and the time to return to play were examined. RESULTS: Subscapularis muscle strain occurred in 3 (3.6%) of 83 fielders and 5 (4.6%) of 108 pitchers, with no significant difference between fielders and pitchers. All players had injuries on the dominant side. Most injuries were located at the myotendinous junction and in the inferior half of the subscapularis muscle. The mean time to return to play was 55.3 ± 40.0 (range, 7-120) days. At a mean 22.7 months after the injury, there were no reinjured players. CONCLUSION: A subscapularis muscle strain is a rare injury among baseball players, but in players whose shoulder pain cannot be given a definite diagnosis, subscapularis muscle strain should be considered as a possible etiology.

The use of tourniquet is useful in terms of blood loss and soft tissue damage in arthroscopic anterior cruciate ligament reconstruction: a retrospective study.

Whether a tourniquet should be used for anterior cruciate ligament reconstruction (ACLR) when the operative field is secured remains controversial. Little is known about the influence of not using a tourniquet on total perioperative blood loss and soft tissue damage. The aim of this study was to compare total perioperative blood loss and soft tissue damage with and without tourniquet use during ACLR. Seventy-seven consecutive ACLRs in 76 patients were performed without tourniquet use at our hospital and enrolled in this study (T- group) between November 2018 and September 2021. The control group (T + group) comprised 55 historical ACLRs in 55 patients performed with tourniquet use at our hospital between April 2017 and September 2018. Total perioperative blood loss, calculated from the change in hemoglobin between that preoperatively and on postoperative day (POD) 1, and indicators of soft tissue damage including serum white blood cell (WBC) counts, creatine phosphokinase (CPK), and C-reactive protein (CRP) values measured on POD 1 and POD 7 were compared between groups. Total blood loss was significantly higher in the T- group (339 ± 216 mL) than in the T + group (258 ± 199 mL; P = 0.030). On POD 1, WBC counts were significantly higher in the T- group (9.7 ± 2.4 × 103 cells/µL) than in the T + group (9.1 ± 2.5 × 103 cells/µL; P = 0.043), CPK levels were significantly higher in the T- group (294 ± 417 U/L) than in the T + group (255 ± 88 U/L; P = 0.046), and CRP levels were also significantly higher in the T- group (1.40 ± 1.12 mg/dL) than in the T + group (0.91 ± 0.76 mg/dL; P = 0.016). No significant differences in WBC counts or CPK or CRP levels were seen between groups on POD 7. Total blood loss and soft tissue damage were significantly increased without tourniquet use during ACLR. No advantage was found for not using a tourniquet in terms of blood loss or soft tissue damage.

Accessory fragment migration in a professional baseball player with bipartite patella: A case report.

INTRODUCTION: Bipartite patella (BP) is usually recognized as an incidental radiographic finding. Therefore, no reports have observed the process of accessory fragment migration. We present the case of a professional baseball pitcher with significant migration of the fragment during follow-up. PRESENTATION OF CASE: A 26-year-old man was diagnosed with symptomatic BP and underwent conservative therapy. Eleven months later, he was unable to play baseball because of gradually worsening knee pain without obvious trauma. On radiographs, the accessory fragment which had located at the superolateral pole 11 months earlier migrated posterolaterally. The diagnosis of Saupe's type III BP was established, and open excision of the accessory fragment was performed. Postoperatively, full-weight-bearing walking and range-of-motion exercises were started the day after surgery. Three months after surgery, he could pitch with all his power without pain. DISCUSSION: Since our patient was a professional baseball right-handed pitcher who needed to step strongly on his left knee during pitching, strong traction force from the vastus lateralis was likely to have been repeatedly applied to the accessory fragment. It might lead to migration of the accessory fragment. The open excision of the accessory fragment was performed because the accessory fragment had migrated away from the patella body. CONCLUSION: We report a case of professional baseball player with symptomatic BP, in which case the chronological migration of the accessory fragment was observed without obvious trauma. When the accessory fragment is identified without obvious trauma, one of the differential diseases could be a BP.

Efficient Transformation of Polymer Main Chain Catalyzed by Macrocycle Metal Complexes via Pseudorotaxane Intermediate.

Post-synthesis modification of polymers streamlines the synthesis of functionalized polymers, but is often incomplete due to the negative polymer effects. Developing efficient polymer reactions in artificial systems thus represents a long-standing objective in the fields of polymer and material science. Here, we show unprecedented macrocycle-metal-complex-catalyzed systems for efficient polymer reaction that result in 100 % transformation of the main chain functional groups presumably via a processive mode reaction. The complete polymer reactions were confirmed in not only intramolecular reaction (hydroamination) but also intermolecular reaction (hydrosilylation) by using Pd- and Pt-macrocycle-catalyzed systems. The most fascinating feature of the both reactions is that higher-molecular-weight polymers reach completion faster. Various studies suggested that the reactions occur in the catalyst cavity via the formation of a supramolecular complex between the macrocycle catalyst and polymer substrate like pseudorotaxane, which should be of characteristic of the efficient polymer reactions progressing in a processive mode.

Simultaneous bilateral quadriceps tendon rupture in a healthy young male: a case report.

BACKGROUND: Simultaneous bilateral quadriceps tendon rupture is rare, particularly in young individuals with no prior medical history. We present the case of a young man who presented with bilateral quadriceps tendon rupture. CASE PRESENTATION: A 27-year-old Japanese man missed a step while descending a flight of stairs, stumbled, and became aware of severe pain in both knees. He had no past medical history, but was severely obese, with a body mass index of 43.7 kg/m2 (height 177 cm, weight 137 kg). Five days after injury, he was referred to our hospital for examination and treatment. Bilateral quadriceps tendon rupture was diagnosed based on magnetic resonance imaging, and quadriceps tendon repair with suture anchor was performed on both knees 14 days after injury. The postoperative rehabilitation protocol was to immobilize both knees in extension for 2 weeks, then to gradually proceed with weight-bearing and gait training using hinged knee braces. Both knees obtained a range of motion from 0° to 130° without any extension lag by 3 months postoperatively. One year postoperatively, tenderness was evident at the suture anchor in the right knee. That suture anchor was therefore removed in a second operation, and histological evaluation of the tendon of the right knee revealed no pathological changes. As of 19 months after the primary surgery, the patient showed a range of motion from 0° to 140° in both knees, did not complain of any disability, and had fully returned to normal daily activities. CONCLUSIONS: We experienced simultaneous bilateral quadriceps tendon rupture in a 27-year-old man with no past medical history other than obesity. Suture anchor repair was performed for both quadriceps tendon ruptures and achieved a favorable postoperative outcome.

Lateral Patellar Facetectomy Reduces the Incidence of Anterior Knee Pain in Patellar Resurfaced Total Knee Arthroplasty.

Lateral patellar facet impingement (LPFI) can cause anterior knee pain (AKP) after patellar resurfaced total knee arthroplasty (TKA). Recently, lateral patellar facetectomy (LPF), which has been used for LPFI, has been performed during primary TKA, providing good clinical outcomes. However, the effect of LPF on AKP in primary patellar resurfaced TKA has not been sufficiently studied. The purpose of this study was to examine the effect of LPF on the development of AKP in patellar resurfaced TKAs with minimum follow-up of 3 years. This retrospective cohort study included 84 knees of 66 consecutive patients who underwent patellar resurfaced TKA between April 2007 and November 2014 in our hospital. The subjects were divided into two groups: TKA with LPF (LPF group; 47 knees) and TKA without LPF (no-LPF group; 37 knees). Postoperative AKP, the primary outcome, the Japanese Orthopaedic Association (JOA) score, and range of motion were investigated at the final visit and compared between the two groups. Six knees (16.2%) had AKP in the no-LPF group, whereas none of the knees had AKP in the LPF group at the final visit. The incidence of AKP was significantly lower in the LPF group (p = 0.004). The postoperative JOA score and flexion angle were significantly higher in the LPF group than in the no-LPF group. LPF correlated with less incidence of postoperative AKP and improved the JOA score and knee flexion angle. In patellar resurfaced TKA, LPF may be considered an additional maneuver to avoid postoperative AKP.

Patient-Reported Outcomes of Minimally Invasive Distal Linear Metatarsal Osteotomy for Hallux Valgus.

BACKGROUND: Modified Bösch osteotomy, or distal linear metatarsal osteotomy (DLMO), is one of the minimally invasive correctional operations for hallux valgus deformity. Although the clinical and radiographic results of DLMO have been previously shown, the relationship between clinical outcomes using a validated patient-reported outcome measure and radiographic corrections have yet to be evaluated. METHODS: A total of 70 patients (97 feet) treated at our hospital were included in the study. The Self-Administered Foot Evaluation Questionnaire (SAFE-Q) and radiographic data were evaluated at a minimum 1-year follow-up. RESULTS: Scores of all five SAFE-Q subscales showed a statistically significant improvement: pain and pain-related (from 63.3 to 86.6), physical functioning and daily living (from 81.3 to 92.7), social functioning (from 79.5 to 94.4), shoe-related (from 43.1 to 72.3), and general health and well-being (from 67.7 to 92.1). The mean hallux valgus angle improved from 39.1° to 9.3°, and the mean intermetatarsal angle improved from 16.6° to 7.0°. Recurrence and hallux varus at the final follow-up occurred in nine feet (9.3%) and 15 feet (15.5%), respectively. Four of the five SAFE-Q subscale scores improved significantly even in patients with hallux varus. CONCLUSIONS: Distal linear metatarsal osteotomy improves foot-related quality of life in patients with hallux valgus deformity despite of the high rate of postoperative radiographic complication, especially hallux varus. Patients might be willing to tolerate mild hallux varus after DLMO, as indicated by patient-centered clinical results.

Pressurized carbon dioxide lavage reduces the incidence of a radiolucent line around the tibial component two years after total knee arthroplasty.

INTRODUCTION: In cemented total knee arthroplasty (TKA), pressurized carbon dioxide (CO2) lavage prior to cement fixation can eliminate debris at the bone-cement interface and is considered effective for increasing cement penetration and preventing aseptic loosening. Regarding the risk of a preliminary diagnosis of implant loosening, a radiolucent line (RLL) is a valuable sign. The purpose of this study was to compare the incidence of a tibial RLL at 2 years after TKA with and without pressurized CO2 lavage. METHODS: This is a retrospective study. One hundred knees from 98 patients were enrolled in this study. TKA was performed without pressurized CO2 lavage (CO2- group) for the first 47 knees, and with pressurized CO2 lavage (CO2+ group) for the next 53 knees. The depth of cement penetration was measured just after surgery, and the incidence of tibial RLL > 2 mm at 2 years after TKA was determined. RESULTS: Significant differences between groups were not seen regarding pre- and postoperative clinical factors. The depth of cement penetration in each area was significantly higher in the CO2+ group. The frequency of knees with RLL > 2 mm was significantly lower in the CO2+ group than in the CO2- group (p < 0.001). CONCLUSIONS: Pressurized CO2 lavage improved cement penetration and decreased the incidence of tibial RLL > 2 mm at 2 years after TKA.

Characteristics of internal oblique muscle strain in professional baseball players: a case series.

BACKGROUND: Internal oblique muscle strains can develop in professional baseball players, rendering the players unable to continue playing for a certain period. However, the characteristics of this injury are not well known. The purpose of the present study was to investigate the details of the injury and the post injury course of internal oblique muscle strain in professional baseball players. METHODS: The subjects were members of a single Japanese professional baseball team with a total of 188 players (81 fielders and 107 pitchers) who developed internal oblique muscle strains from January 2012 to December 2021. The diagnosis of muscle strain was made on the basis of local pain and magnetic resonance imaging findings. The incidence of internal oblique muscle strain, the details of the site of the injury, and the time to return to play were examined. RESULTS: There were 28 cases in 23 players (12.2%) of internal oblique muscle strain. The players were 16 fielders (24.7%) and 7 pitchers (7.5%), with a significantly greater incidence in fielders (p = 0.001). Although internal oblique muscle strain was more common on the side contralateral to the batting or pitching side, it occurred on either side. Most of the injury sites were at the region of the muscle insertion to the lower ribs. At a mean time of 36.5 months after the initial injury, 5 players (21.7%) developed another internal oblique muscle strain. The mean time to return to play was 27.7 ± 9.7 days (range, 4-53 days). CONCLUSIONS: Baseball players who have symptoms at the side of the trunk should be regarded as having possible internal oblique muscle strain, and proactive examination should be considered.

Association between magnetic resonance imaging characteristics and pathological findings in entire posterior cruciate ligament with mucoid degeneration.

Magnetic resonance imaging (MRI) findings of a tram-track appearance and celery stalk appearance in mucoid degeneration of the cruciate ligament are valuable; however, their pathological basis is unclear. Because these appearances are generally seen throughout the entire ligament, the association between MRI findings and pathological findings must be verified in specimens of the whole degenerated ligament, including the ligamentous attachments to bone. We herein report two cases of mucoid degeneration of the posterior cruciate ligament with osteoarthritis of the knee requiring total knee arthroplasty. The entire degenerated ligament, including the ligamentous attachments to bone, was removed and pathologically evaluated. On pathological examination, the central portion of the lesion showed typical mucoid degeneration, whereas the marginal and adherent portions showed normal ligament tissue, consistent with a tram-track appearance on T2-weighted MRI. The fibrous normal ligament tissues in the longitudinal direction in regions of mucoid degeneration were consistent with a celery stalk appearance on T2-weighted MRI. No mucoid degeneration was found in the attachment area. The tram-track appearance and celery stalk appearance of mucoid degeneration on MRI can be explained by the pathological findings.

Optimal time period for blood glucose level evaluation after total knee arthroplasty in patients without diabetes: a prospective, observational study.

BACKGROUND: Postoperative hyperglycemia has been reported to be a risk factor for postoperative infection even in patients without diabetes mellitus (DM). However, there is no standard for how long blood glucose level (BGL) monitoring should be performed after total knee arthroplasty (TKA). The purpose of this study was to determine the optimal time period for BGL evaluation after TKA in patients without DM. METHODS: This prospective study included 132 knees of 110 patients who underwent TKA between March 2018 and July 2021 in our hospital. Fasting BGLs were measured preoperatively, at 9:00 PM on the day of surgery (DOS), and at 7:00 AM on postoperative days (PODs) 1, 2, and 3. Patients were divided into two groups with a preoperative hemoglobin A1c (HbA1c) cut-off value of 5.9%, and the BGLs on POD 1 were compared between the two groups. RESULTS: The BGLs were significantly higher on the DOS, POD 1, and POD 2 than preoperative levels. The BGL was significantly higher on POD 1 than at any other time point. Patients with an HbA1c ≥ 5.9% had significantly higher BGLs than those with an HbA1c < 5.9% on POD 1. CONCLUSIONS: The optimal time period for BGL evaluation after TKA in patients without DM was considered to be from postoperative to POD 2. Patients with an HbA1c ≥ 5.9% may require careful perioperative glycemic control.

Isolated Talonavicular Arthrodesis for Traumatic Talonavicular Arthritis: Report of 2 Cases With Gait Analyses.

Isolated talonavicular arthrodesis is one of the surgical procedures for patients with talonavicular arthritis. However, the 3-dimensional kinematic behavior of the hip, knee, and foot/ankle complex during walking after the arthrodesis remains unclear. The clinical outcomes and gait analyses of 2 cases who underwent isolated arthrodesis for talonavicular osteoarthritis with chronic dislocated navicular fracture are presented. Gait analysis was carried out in both cases 1 year after surgery to clarify the side-to-side differences in the ranges of motion of the hip, knee, and foot/ankle complex during walking. Both cases showed good clinical results and radiographic bone union. The kinematic data of the gait analyses showed considerable restriction in the range of motion of the ankle in all 3-dimensional planes for the fused foot compared with the contralateral side. Additionally, hyperextension of the knee in the late stance of gait on the operated side was observed in both cases. When talonavicular arthrodesis was performed for talonavicular osteoarthritis with chronic dislocated navicular fracture, postoperative generalized stiffness of the ankle and future disorder of the knee should be considered.Levels of Evidence: Level V: Case report.

Not Using a Tourniquet May Reduce the Incidence of Asymptomatic Deep Venous Thrombosis After ACL Reconstruction: An Observational Study.

BACKGROUND: Deep venous thrombosis (DVT) and pulmonary embolism are serious potential complications after anterior cruciate ligament reconstruction (ACLR). Little is known about the influence of tourniquet use on the incidence of DVT after ACLR. PURPOSE: To compare the incidence of DVT after ACLR with and without the use of a tourniquet. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Between November 2018 and May 2020, a total of 60 consecutive ACLRs in 60 patients, including 7 revision surgeries, were performed without tourniquet use at our hospital and were enrolled in this study (T- group). In addition, 55 consecutive ACLRs in 55 patients, including 10 revision surgeries, were performed with tourniquet use between April 2017 and September 2018 and were enrolled as the control group (T+ group). DVT was diagnosed using ultrasonography of both legs performed preoperatively and at postoperative week 1. The incidence of postoperative DVT was compared between the T- and T+ groups. Logistic regression analysis was performed to evaluate the effect of older age (≥40 vs <40 years) and tourniquet use on the occurrence of DVT. RESULTS: No DVTs were detected preoperatively. The incidence of postoperative DVT was significantly lower in the T- group compared with the T+ group (1 patient [1.7%] vs 9 patients [16.4%]; P = .005). All patients with DVT were asymptomatic. Although the mean operative time was not significantly different (80.8 minutes in the T+ group vs 78.5 minutes in the T- group; P = .461), the mean blood loss from the drain was significantly lower in the T- group than in the T+ group (149.9 vs 201.9 mL; P < .001). Age ≥40 years and tourniquet use were significantly related to the occurrence of DVT (odds ratio, 8.3 [95% CI, 1.9-36.8]; P = .005; and odds ratio, 8.8 [95% CI, 1.0-75.3]; P = .047, respectively). CONCLUSION: ACLRs performed without tourniquet resulted in a significantly lower incidence of DVT after ACLR and significantly less bleeding from drains. If adequate visibility of the surgical field is obtained, ACLR without tourniquet use may reduce the incidence of DVT.

Suture Anchor Repair With Fully Threaded Knotless Anchors for Quadriceps Tendon Rupture Resulted in Favorable Outcomes After 2 Years.

PURPOSE: To investigate clinical outcomes over 2 years in cases of quadriceps tendon rupture (QTR) that were surgically treated using fully threaded knotless anchors. METHODS: A total of four knees in four male patients with QTR repaired with fully threaded knotless anchors at our hospital from November 2017 to January 2019 were enrolled. Mean patient age at surgery was 65.3 years (range: 61-70 years). Intraoperatively, stability of the sutured site was confirmed by knee flexion to 90°. Full weight walking with the orthosis in extension was commenced on the seventh postoperative day. Surgical findings, pathologies of the ruptured quadriceps tendons, and postoperative clinical outcomes were evaluated in all patients. RESULTS: The QTR was complete in three cases and partial in one. Average surgical duration was 58.5 (range: 49-74) minutes. Pathological evaluation revealed hyaline degeneration with granulation of the quadriceps tendon in two cases. No complications, such as infection and rerupture, occurred. Magnetic resonance imaging performed 1 year postoperatively confirmed complete healing of the repaired tendon. The mean follow-up period was 35.5 months (range: 24-46 months). None of the patients had extension lag of the knee, and mean Lysholm score and range of flexion were 95.3 (range: 85-100) and 141.3° (range: 140-145°), respectively, at the final follow-up. CONCLUSIONS: Clinical outcomes were favorable in all cases, including two cases with pathological degenerative changes. Suture anchor repair with fully threaded knotless anchors can be considered a minimally invasive and effective method for QTR, with sufficient strength to allow early rehabilitation.

Benign Neglect of Anomalous Insertion of the Anterior Horn of the Medial Meniscus as an Incidental Finding During Knee Arthroscopy.

PURPOSE: To evaluate the clinical results following arthroscopic surgery in patients with anomaly of the anterior horn of the medial meniscus (AHMM) that was found unexpectedly during surgery and discuss whether resection is necessary in patients without anteromedial knee pain (AMKP). METHODS: Between May 2014 and April 2017, a total of 387 knee arthroscopies in 379 patients were performed. Among these, 11 knees in 11 patients showed an anomalous insertion of the AHMM (incidence, 2.8%), and all 11 patients were included in this study. For these 11 patients, medical records including preoperative diagnosis, arthroscopic findings, and pre- and postoperative clinical evaluations were analyzed. RESULTS: None of the patients complained of AMKP before arthroscopy. Two patients were diagnosed with lateral meniscus injury and the other 9 patients were diagnosed with medial meniscus injury. All anomalies of the AHMM were found incidentally during arthroscopic surgery. The anomaly formed a band-like structure arising from the anterior portion of the medial meniscus and was attached to the anterior aspect of the ACL and femoral intercondylar notch. All 11 patients underwent partial meniscectomy, but anomalies of the AHMM were not resected. One patient was excluded from clinical evaluation, as that patient required subsequent total knee arthroplasty due to osteoarthritis. For the other 10 patients, mean follow-up was 36.8 months (range, 26-61 months). Knee pain was relieved, and none developed postoperative AMKP. Mean Lysholm score improved significantly from 55.9 to 91.2 (P < .001). CONCLUSIONS: The incidence of the anomaly was 2.8% in our study. If the patient has no AMKP before arthroscopic surgery, anomaly of the AHMM is a silent lesion that does not warrant resection. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Ring-shaped meniscus formation may arise from the regenerative response to meniscectomy during growth spurts: A case report.

INTRODUCTION: Ring-shaped meniscus is very rare and generally considered to be a congenital malformation. Here, we report a case of newly formed ring-shaped meniscus-like tissue following arthroscopic partial meniscectomy for a complete discoid lateral meniscus. PRESENTATION OF CASE: A 14-year-old boy underwent arthroscopic partial meniscectomy for complete discoid lateral meniscus of the left knee. The growth plates were present at the surgery. Although pain improved immediately after surgery, he reported left knee pain at the 7-month follow-up. Magnetic resonance imaging revealed a bucket-handle tear of the lateral meniscus and a second arthroscopic surgery was performed. During arthroscopy, we found that the anterior and posterior horns of the lateral meniscus were connected by meniscus-like tissue forming a ring-shaped meniscus and the newly formed interhorn meniscal bridge was resected. Histological evaluation indicated that the newly formed tissue was meniscus-like tissue that had appeared secondary to tissue repair. He visited our hospital at 16 years old, after the growth plates had closed, complaining of right knee pain. Arthroscopic partial meniscectomy was performed for complete discoid lateral meniscus of the right knee. As of two years after this surgery, no morphological changes have been observed. DISCUSSION: Although the exact mechanisms of meniscus-like tissue formation remain unclear, the growth spurt may promote the mechanisms of tissue repair, forming ring-shaped meniscus-like tissue. CONCLUSION: This is the first case of ring-shaped meniscus-like tissue forming after partial resection of a complete discoid lateral meniscus. Ring-shaped meniscus-like tissue can develop in growing patients.

Factors Affecting Longer Surgical Times in Total Knee Arthroplasty for Obese Patients-A Comparative Study between High- and Nonhigh-Volume Surgeons.

Obesity has a negative influence on surgical times in total knee arthroplasty (TKA). Our purpose in this multicenter study was to compare surgical times between high- (HV) and nonhigh-volume (NHV) surgeons and clarify the important factors affecting longer surgical times in primary TKA for obese patients. A total of 798 knees, average age 75.1 years, were enrolled. All TKAs were done using the same measured resection technique by 25 surgeons at 12 facilities and were divided into three groups based on body mass index (kg/m2) of the patients (Group A: <24.9, Group B: 25-29.9, Group C: ≥30). Operative techniques including four surgical steps (surgical exposure, bone cutting, trial and fixation of the permanent component, and wound closure) were evaluated both in HV and NHV surgeons. In classifying surgeon volume, HV surgeons had performed >100 TKAs annually for many years, and other surgeons who had performed <100 TKAs annually were defined as NHV surgeons. Patient demographics, surgical details, and surgical times in each phase were compared using nonrepeated measures of analysis of variance and a post hoc Student-Newman-Keuls test. A total of 331, 327, 140 TKAs were allocated to Groups A, B, C, respectively. Regarding patient demographics, patients in Group C were younger and had the worst ranges of motion. The longest surgical time was observed in Group C of NHV surgeons (p < 0.05). Concerning each surgical phase, surgeons took much more time in surgical exposure and fixation of the permanent component for obese patients in NHV surgeons (p < 0.05). Our results suggest that younger age and lower range of motion were observed in obese patients, which led to longer surgical times. In addition, NHV surgeons took much time in surgical exposure and fixation of the permanent component for obese patients, while surgical time was similar among groups for HV surgeons.

Modified Goel's Methods for Basilar Impression: A Case Report with Literature.

We report the case of a 57-year-old woman who had basilar impression manifesting as severe myelopathy and occipital neuralgia and was treated by distraction and fixation performed using a modification of Goel's method. Magnetic resonance imaging (MRI) and computed tomography (CT) scans showed severe myelocompression by the dens of the axis from the ventral side and occipitalization of the atlas. After traction using a Halo vest, C1-2 facet distraction and fixation was performed in one stage using a modified Goel's method. Although Goel et al. used a custom-made spacer to distract the facet joints, we used a threaded titanium cylindrical cage that was inserted into the joint to fix the C1-2 facet joint with posterior fixation from occipital bone to C5. Postoperatively, gradual symptomatic and neurological amelioration were observed. The atlantoaxial joints were bone-fused at 3 years post-operation. Distraction and fixation performed using this modified version of Goel's method was effective for treating basilar invagination. The threaded titanium cylindrical cage provided adequate C1-2 space and strong initial fixation.

Arthroscopic Visualization of Abnormal Movement of Discoid Lateral Meniscus With Snapping Phenomenon.

Discoid lateral meniscus with snapping phenomenon is a rare pathologic condition. The purpose of this article is to present an arthroscopic technique for the treatment of discoid lateral meniscus with snapping phenomenon. The patient is placed in the supine position for confirmation of snapping. As the patient's knee bends, it can be confirmed by arthroscopy that the posterior horn of the discoid lateral meniscus moves posteriorly and the central portion of the discoid lateral meniscus moves anteriorly at the same time with snapping at deep flexion angles. The anterior segment of the discoid lateral meniscus is found to be redundant and is often folded. On the contrary, as the patient's knee extends, the central portion is returned to the original position accompanied by snapping at nearly full extension. After excision of the central portion, the movement of the meniscus is evaluated again and the disappearance of the snapping phenomenon can be confirmed. Although it includes limitations, this application is easy and would certainly help surgeons to treat snapping knee with discoid lateral meniscus.