Knee Arthroscopy Following Total Knee Arthroplasty is Not Associated With an Elevated Risk of Infection.

BACKGROUND: Recent literature has suggested that knee arthroscopy (KA) following ipsilateral primary total knee arthroplasty (TKA) may be associated with an increased risk of periprosthetic joint infection (PJI). However, prior studies on this subject have relied on insurance databases or have lacked control groups for comparison. This study aimed to evaluate the risk of PJI in patients undergoing ipsilateral KA after primary TKA at a single institution. METHODS: Our total joint registry was queried to identify 167 patients (178 knees) who underwent ipsilateral KA for any indication other than infection following primary TKA (KA + TKA group). The average time from TKA to KA was 2.1 ± 2.3 years. The average follow-up from primary TKA and from KA was 8.4 ± 5.4 years and 6.3 ± 5.4 years, respectively. The mean patient age was 63 ± 11 years, the mean body mass index was 31 ± 5, and 64% were women. The most common indications for KA were patellar clunk or patellofemoral synovial hyperplasia (66%) and arthrofibrosis (16%). Patients in the KA + TKA group were matched to 523 patients who underwent TKA without subsequent KA (TKA group) based on age, sex, date of surgery, and body mass index. The primary outcome measure was survivorship free from PJI. RESULTS: There was no statistical difference in the overall rate of PJI between the KA + TKA group (n = 2, 1.1%) compared to the TKA group (n = 3, 0.6%) (hazard ratio 2.0, 95% confidence interval 0.3 to 12.0, P = .4). At 5 and 10 years after TKA, there was no difference in survivorship free of PJI between the 2 groups (P = .8 and P = .3, respectively). CONCLUSIONS: A PJI is a rare complication of KA after TKA. The rate of PJI in patients undergoing KA following TKA is not significantly increased. LEVEL OF EVIDENCE: III.

Risk factors for secondary meniscus tears can be accurately predicted through machine learning, creating a resource for patient education and intervention.

PURPOSE: This study sought to develop and internally validate a machine learning model to identify risk factors and quantify overall risk of secondary meniscus injury in a longitudinal cohort after primary ACL reconstruction (ACLR). METHODS: Patients with new ACL injury between 1990 and 2016 with minimum 2-year follow-up were identified. Records were extensively reviewed to extract demographic, treatment, and diagnosis of new meniscus injury following ACLR. Four candidate machine learning algorithms were evaluated to predict secondary meniscus tears. Performance was assessed through discrimination using area under the receiver operating characteristics curve (AUROC), calibration, and decision curve analysis; interpretability was enhanced utilizing global variable importance plots and partial dependence curves. RESULTS: A total of 1187 patients underwent ACLR; 139 (11.7%) experienced a secondary meniscus tear at a mean time of 65 months post-op. The best performing model for predicting secondary meniscus tear was the random forest (AUROC = 0.790, 95% CI: 0.785-0.795; calibration intercept = 0.006, 95% CI: 0.005-0.007, calibration slope = 0.961 95% CI: 0.956-0.965, Brier's score = 0.10 95% CI: 0.09-0.12), and all four machine learning algorithms outperformed traditional logistic regression. The following risk factors were identified: shorter time to return to sport (RTS), lower VAS at injury, increased time from injury to surgery, older age at injury, and proximal ACL tear. CONCLUSION: Machine learning models outperformed traditional prediction models and identified multiple risk factors for secondary meniscus tears after ACLR. Following careful external validation, these models can be deployed to provide real-time quantifiable risk for counseling and timely intervention to help guide patient expectations and possibly improve clinical outcomes. LEVEL OF EVIDENCE: III.

John N. Insall Award: Randomized Clinical Trial of Cementless Versus Cemented Tibial Components: Durable and Reliable at a Mean 10-Years Follow-Up.

BACKGROUND: Cementless fixation is gaining popularity for primary total knee arthroplasties (TKAs). The prior 5-year results of our randomized clinical trial that included 3 different tibial designs found minimal differences. The purpose of the current study was to investigate the 10-year results in the same cohort. METHODS: Between 2003 and 2006, 389 primary TKAs were randomized: traditional modular cemented tibia (135); hybrid (cemented baseplate with uncemented pegs) monoblock tibia (128); and cementless monoblock tibia (126). Implant survivorships, radiographs, and clinical outcomes were analyzed. Mean age at TKA was 68 years (range, 41 to 85), 46% were male, and mean body mass index was 32 (range, 21 to 59). The mean follow-up was 10 years. RESULTS: The 10-year survivorship free of any revision was similar between the hybrid monoblock and cementless monoblock groups at 96%, but lower (89%) for the traditional modular cemented tibia (P = .05). The traditional modular cemented tibia group had significantly more revisions for aseptic tibial loosening than the other 2 groups (7 versus 0%) at 10 years (P = .003). The traditional modular cemented tibia group had significantly more nonprogressive radiolucent lines than the hybrid and cementless monoblock groups (24, 12, and 9%, respectively). Clinical outcomes were similar and excellent between all 3 groups. CONCLUSION: Cementless and hybrid monoblock tibial components have excellent implant survivorship (96%) with no cases of aseptic tibial loosening to date. The traditional cemented modular tibial group had a 7% cumulative incidence of aseptic loosening at 10 years. LEVEL OF EVIDENCE: Level I, Prospective Randomized Control Trial.

Counterpossibles in science: an experimental study.

A counterpossible is a counterfactual whose antecedent is impossible. The vacuity thesis says all counterpossibles are true solely because their antecedents are impossible. Recently, some have rejected the vacuity thesis by citing purported non-vacuous counterpossibles in science. One limitation of this work, however, is that it is not grounded in experimental data. Do scientists actually reason non-vacuously about counterpossibles? If so, what is their basis for doing so? We presented biologists (N = 86) with two counterfactual formulations of a well-known model in biology, the antecedents of which contain what many philosophers would characterize as a metaphysical impossibility. Participants consistently judged one counterfactual to be true, the other to be false, and they explained that they formed these judgments based on what they perceived to be the mathematical relationship between the antecedent and consequent. Moreover, we found no relationship between participants' judgments about the (im)possibility of the antecedent and whether they judged a counterfactual to be true or false. These are the first experimental results on counterpossibles in science with which we are familiar. We present a modal semantics that can capture these judgments, and we deal with a host of potential objections that a defender of the vacuity thesis might make.

COVID-19-Positive Testing in Minnesota High School Fall and Winter Sports: A Guide for Sports Risk.

OBJECTIVE: To assess the effectiveness of coronavirus disease 2019 (COVID-19) prevention strategies used during sports participation. DESIGN: To analyze prospective reports of student-athletes with COVID-19-positive tests to assess prevention strategies and risk factors by sports and seasons. SETTING: Minnesota high schools. PARTICIPANTS: Fall 2020 (August 24-October 30) and winter 2021 (January 2-March 12) student-athletes. ASSESSMENT OF RISK FACTORS: Sports, indoor location, mask use, physical distancing, and season. MAIN OUTCOME MEASURES: COVID-19-positive test rates. METHODS: Self-selected schools voluntarily reported, in 2-week intervals, the number of student-athletes with COVID-19-positive tests in each sport and the number of athletes participating in each sport during the fall and winter sports seasons. The positive testing rates per 100 000 athletes were calculated for participants in each sport and compared by sports type and risk variables. RESULTS: The high school age community-positive testing rate was 1298 per 100 000 students in the fall and 2396 in the winter. The student-athlete positive testing rate was 1500 per 100 000 athletes during the fall and 2800 during the winter (χ2 = 1.98, df = 1, P = 0.350). Positive tests per 100 000 athletes ranged from 197 (girls alpine skiing) to 4151 (wrestling). The incidence rates comparing indoor with outdoor sports (P = 0.001) and close-contact with physically distanced sports (P = 0.023) were significantly different, but the incidence rates comparing indoor masked with unmasked sports (P = ns) were not different. CONCLUSION: Athletes competing in outdoor individual sports have less risk of a COVID-19-positive test compared with age-matched individuals in the community and indoor sports participants either wearing or not wearing masks during competition. Unmasked athletes in close proximity have the highest positive test rates, and unenforced masking is not associated with lower positive testing rates. More study is needed to understand mask effectiveness.

Validity Indices of the King-Devick Concussion Test in Hockey Players.

OBJECTIVE: To compare the validity indices of the King-Devick (KD) test in hockey players using any increase in test time over baseline to a 6-second increase as a positive concussion test. We hypothesized the KD test using the 6-second change would yield greater validity indices. DESIGN: Prospective observational cohort study. SETTING: Sports complex. PARTICIPANTS: Sixty-five male hockey players aged 13 to 20 years. INDEPENDENT VARIABLE: Concussion diagnosis. MAIN OUTCOME MEASURES: Time to complete the KD test. Sensitivity (SN), specificity (SP), and the positive likelihood ratios (LRs+) were calculated using 2 thresholds for a positive test: (1) any increase in time and (2) an increase of 6 seconds or greater. RESULTS: Eighteen players (27.7%) were diagnosed with a concussion. Using any increase in time as a positive test yielded the following: SN 72.2%, SP 78.7%, LR+ 3.4, and LR- 0.4. Using the 6-second threshold yielded the following: SN 44.4%, SP 93.6%, LR+ 7.0, and LR- 0.6. A receiver operator curve analysis confirmed 6.40 seconds or greater maximized the LR+. CONCLUSIONS: A 6-second or greater increase in the KD test performance provides greater validity in diagnosing concussion as compared with any increase in performance time.

Revision Total Knee Arthroplasty With a Rotating-Hinge Prosthesis Mated to a Well-Fixed Femoral Sleeve.

BACKGROUND: Some knee systems have the unique capability to mate a new hinged femoral component to a well-fixed metaphyseal sleeve from a prior revision. We compared survivorship, radiographs, and clinical outcomes of a rotating-hinge total knee arthroplasty mated to a new metaphyseal sleeve vs a well-fixed sleeve. METHODS: Sixty patients with an S-ROM Noiles (DePuy Synthes, Warsaw, IN) rotating-hinge total knee arthroplasty implanted from 1998 to 2019 were retrospectively reviewed. Nine patients (15%) had the femoral component mated to a well-fixed sleeve and 51 patients (85%) had a new sleeve. Mean age was 68 years, 68% were female, and mean body mass index was 33 kg/m2. The incidences of re-revision and reoperation were calculated, Knee Society Scores were measured, and radiographs were reviewed. Mean follow-up was 5 years. RESULTS: There were 2 re-revisions (22%) in patients with a well-fixed sleeve: 1 for infection and 1 for aseptic loosening of the femur and tibia. There were no unique failures including the taper junction. Nine patients (18%) with a new sleeve were re-revised: 7 for infection and 2 for tibial aseptic loosening. The mean Knee Society Score for all patients improved from 39 to 73. Radiographically, all components were well fixed except for one loose femur in a patient with a new sleeve. CONCLUSION: Mating an S-ROM femur to a well-fixed sleeve from a prior revision is a safe, simple, and durable option in the short term that prevents morbidity associated with removal of a well-fixed sleeve. No new modes of failure were observed. LEVEL OF EVIDENCE: IV (retrospective), Therapeutic.

Contemporary Outcomes of Transfemoral Amputation After Total Knee Arthroplasty.

BACKGROUND: Transfemoral amputation (TFA) is a salvage procedure for unreconstructable failed total knee arthroplasty (TKA). Prior studies have reported poor outcomes, patient survival, and prosthetic use. The purpose of this study was to analyze patient outcomes and prosthetic utilization in a contemporary group of patients undergoing TFA in the setting of a TKA. METHODS: We reviewed 112 patients undergoing TFA with a prior TKA. Indications for amputation and postoperative functional measures were captured through chart review. Patients were contacted by survey to assess the quality of life. The mean follow-up after TFA was 4 years. RESULTS: Amputations were performed for a chronically infected TKA (n = 87, 78%) and an ischemic limb without signs of an infected TKA (n = 22, 20%). The 10-year survival after TFA was 21%. Of the patients not lost to follow-up, 53 (47%) patients were fitted for a prosthesis. Patients who underwent a TFA after the year 2000 were more likely to be fit for a prosthesis (odds ratio 7.27, P < .01); however, patients were likely to be ambulatory before TFA than after TFA (odds ratio 3.68, P < .01). After TFA, the mean 12-Item Short Form Survey scores for the mental and physical components were 54 ± 13 and 34 ± 7, with no difference in scores between patients fitted for a prosthesis and those who were not (P > .05). CONCLUSION: Patients undergoing a TFA after TKA due to failure of the TKA are more likely to be fit for a prosthesis; however, they reported no better quality of life and satisfaction compared with patients not fit for a prosthesis. LEVELS OF EVIDENCE: Level III, Therapeutic.

Editorial Commentary: Autograft Beats Allograft for Most Knee Ligament Surgery.

Knee ligament reconstruction can be performed with autograft or allograft. The use of an autograft has been shown to improve outcomes in primary anterior cruciate ligament reconstruction for young, active patients, and also in revision anterior cruciate ligament reconstruction surgery. A systematic review of posterior cruciate ligament reconstruction showed no difference in outcomes between autograft and allograft tissue. There is a paucity of data comparing autograft versus allograft for fibular collateral ligament and posterolateral corner reconstructions, alone or combined with other ligament surgery. Allograft advantages include no donor site morbidity and reduced operative time. Disadvantages include increased cost and higher failure rates in younger patients. Autograft tissue should be considered in younger, active patients whenever possible.

Hamstring Autograft Anterior Cruciate Ligament Reconstruction Using an All-Inside Technique With and Without Independent Suture Tape Reinforcement.

PURPOSE: To compare the (1) rates of complications and reoperations, (2) rate of anterior cruciate ligament (ACL) graft failure, and (3) patient-reported outcomes (PROs) among patients after hamstring autograft ACL reconstruction (ACLR) with and without independent suture tape reinforcement at a minimum 2-year clinical follow-up. METHODS: We performed a 1:2 matched-cohort comparison of patients who underwent hamstring autograft ACLR with and without independent suture tape reinforcement between July 2011 and July 2017. Patients were matched according to age, sex, body mass index, preinjury Tegner activity score, and concomitant meniscal injury. Medical records were reviewed for demographic characteristics, additional injuries, and concomitant procedures. PRO scores (including Tegner activity, Lysholm, and International Knee Documentation Committee scores) and physical examination findings were collected both preoperatively and at a minimum of 2 years postoperatively. RESULTS: Overall, 108 patients who underwent ACLR were included: 36 patients (mean age, 25.3 years; range, 13-44 years) with independent suture tape reinforcement and 72 patients (mean age, 24.9 years; range, 13-54 years) without suture tape reinforcement. Overall, 5 of 36 suture tape patients (14%) and 10 of 72 control patients (14%) underwent reoperations. At an average follow-up of 26.1 months in the suture tape cohort and 31.3 months in the control cohort, 1 patient in the suture tape cohort and 4 patients in the control cohort experienced graft failure. There were no statistically significant differences between the suture tape and control groups regarding return-to-sport rate (89% and 88%, respectively), postoperative International Knee Documentation Committee score (94.4 and 93.8, respectively), and postoperative Lysholm score (95.6 and 94, respectively). There was a statistically significant difference between the suture tape and control groups in postoperative Tegner activity score, at 7.1 (95% confidence interval, 6.5-7.6) and 6.4 (95% confidence interval, 6.2-6.6), respectively (P = .026). CONCLUSIONS: ACLR with hamstring autograft and independent suture tape reinforcement was performed safely with low rates of complications, graft failure, and reoperations with similar PROs, function, and return-to-sport rates when compared with hamstring autograft ACLR without suture tape reinforcement at a minimum 2-year follow-up. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Post-arthroscopic Subchondral Insufficiency Fractures of the Knee Yield High Rate of Conversion to Arthroplasty.

PURPOSE: To evaluate both the potential causes and resultant outcomes in patients in whom subchondral insufficiency fracture of the knee (SIFK) develops after arthroscopy. METHODS: We performed a retrospective review of all patients with a magnetic resonance imaging diagnosis of SIFK after arthroscopic meniscectomy and chondroplasty over a 12-year period. RESULTS: A total of 28 patients were included, with a mean age of 61 years and mean follow-up period of 5.7 years. SIFK showed a predilection for the medial compartment (n = 25, 89%), specifically the medial femoral condyle (n = 21, 75%). In 7 patients (25%), SIFK developed in both the femoral condyle and tibial plateau in the ipsilateral compartment. Fifteen patients (54%) went on to conversion to arthroplasty at a mean of 0.72 years. The rate of survival free of conversion to arthroplasty was 57%, 45%, and 40% at 1 year, 2 years, and 5 years, respectively. Furthermore, 63% of patients with a meniscal tear and SIFK in the same compartment went on to arthroplasty (P = .04). There was an increased risk of conversion to arthroplasty if SIFK was present in both the femur and tibia in the same compartment (P = .04). A higher Kellgren-Lawrence grade at the time of the SIFK diagnosis increased the likelihood of eventual arthroplasty (P = .03). The presence of SIFK in both the femur and tibia in the ipsilateral compartment, an increased Kellgren-Lawrence grade, and a meniscal tear or prior meniscectomy in the same compartment as SIFK were associated with an increased risk of eventual arthroplasty. CONCLUSIONS: Post-arthroscopic SIFK most commonly occurs in the medial compartment, particularly in patients who underwent a prior meniscectomy. The presence of meniscal root and radial tears in these patients is notable (75%). Ultimately, there is a high rate of progression of arthrosis (33%) and eventual conversion to arthroplasty. LEVEL OF EVIDENCE: Level IV, case series.

Proceedings From the Ice Hockey Summit III: Action on Concussion.

OBJECTIVES: The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these 5 objectives: (1) describe sport related concussion (SRC) epidemiology; (2) classify prevention strategies; (3) define objective, diagnostic tests; (4) identify treatment; and (5) integrate science and clinical care into prioritized action plans and policy. METHODS: Our action plan evolved from 40 scientific presentations. The 155 attendees (physicians, athletic trainers, physical therapists, nurses, neuropsychologists, scientists, engineers, coaches, and officials) voted to prioritize these action items in the final Summit session. RESULTS: To (1) establish a national and international hockey database for SRCs at all levels; (2) eliminate body checking in Bantam youth hockey games; (3) expand a behavior modification program (Fair Play) to all youth hockey levels; (4) enforce game ejection penalties for fighting in Junior A and professional hockey leagues; (5) establish objective tests to diagnose concussion at point of care; and (6) mandate baseline testing to improve concussion diagnosis for all age groups. CONCLUSIONS: Expedient implementation of the Summit III prioritized action items is necessary to reduce the risk, severity, and consequences of concussion in the sport of ice hockey.

Arthritic progression secondary to meniscus root tear treated with knee arthroplasty demonstrates similar outcomes to primary osteoarthritis: a matched case-control comparison.

PURPOSE: There is limited data comparing the outcomes of knee arthroplasty for arthritis secondary to meniscus root tear versus primary osteoarthritis. The aim of this 2:1 matched case control series was to compare outcomes in patients who underwent arthroplasty for arthritis following a meniscus root tear (root tear cohort-"RTC") with a control group of patients with primary osteoarthritis (primary osteoarthritis-"controls"). The authors hypothesized that the meniscus root tear patients would have similar clinical outcomes, return to activity, complication and reoperation rates as their matched controls. METHODS: A consecutive series of patients who had a clinically and radiographically confirmed meniscus root tear between 2002 and 2017 at a mean 4.8 year follow-up that developed secondary arthritis were matched 2:1 by laterality, surgery, age at surgery, date of surgery, sex, and surgeon to a control group of patients with primary osteoarthritis, without a root tear, who underwent arthroplasty. No patients were lost to follow-up. Patient demographics, Kellgren-Lawrence grades at the time of surgery, pre- and post-operative Knee Society Score pain and function scores, Tegner score, complications, and survival free of reoperation were analyzed between groups. RESULTS: A total of 225 subjects were identified, including 75 root tear cohort patients (13 UKA, 62 TKA) and 150 control patients. The root tear cohort had significantly lower Kellgren-Lawrence grades than the control group at the time of arthroplasty (p ≤ 0.001), but similar baseline pre-operative Knee Society Score pain, Knee Society Score function, and Tegner activity scale score. Post-operatively, Knee Society Score pain scores were comparable, and root tear cohort Knee Society Score function scores statistically significantly improved (p ≤ 0.007). Complication rates and survival free of reoperation at final follow-up were not statistically significantly different between groups. CONCLUSION: Patients treated with arthroplasty for secondary arthritis after a meniscus root tear demonstrated less severe radiographic arthritis, but similar pre-operative pain levels compared to matched controls with primary osteoarthritis. The root tear cohort patients demonstrated improved outcomes with respect to function, and similar outcomes with respect to pain, activity level, complication rates, and reoperation rates. The authors conclude that arthroplasty can be a reliable option for selected patients with an irreparable root tear and ongoing pain and dysfunction refractory to non-operative management, even in the setting of less advanced osteoarthritis on X-ray. LEVEL OF EVIDENCE: III.

Brain vital signs detect concussion-related neurophysiological impairments in ice hockey.

There is a growing demand for objective evaluations of concussion. We developed a portable evoked potential framework to extract 'brain vital signs' using electroencephalography. Brain vital signs were derived from well established evoked responses representing auditory sensation (N100), basic attention (P300), and cognitive processing (N400) amplitudes and latencies, converted to normative metrics (six total). The study evaluated whether concussion-related neurophysiological impairments were detected over the duration of ice hockey seasons using brain vital signs. Forty-seven Tier III, Junior A, male ice hockey players were monitored over two seasons. Twelve sustained concussions after baseline testing then completed post-injury and return-to-play assessments. Twenty-three were not diagnosed with a concussion during the season and completed both baseline and post-season testing. Scores were evaluated using a repeated-measures analysis of variance with post hoc two-tailed paired t-tests. Concussion resulted in significantly increased amplitude and delayed latency scores for all six brain vital signs (P < 0.0001). Importantly, significant changes at return-to-play were also detected in basic attention (P300) amplitude, indicating persistent subclinical impairment. In the non-concussed group, there was also a significant change between baseline and post-season (P = 0.0047), with specific decreases in cognitive processing (N400) speed (P = 0.011) and overall total score (P = 0.002).

Medial Versus Lateral Meniscus Root Tears: Is There a Difference in Injury Presentation, Treatment Decisions, and Surgical Repair Outcomes?

PURPOSE: To determine (1) the demographic characteristics as well as radiographic findings of medial versus lateral meniscal root tears at time of presentation, (2) treatment decisions and clinical outcomes of patients undergoing medial versus lateral root repair, and (3) risk factors for worse clinical and radiographic outcomes. METHODS: A retrospective review was performed to identify patients with symptomatic, medial, or lateral meniscus posterior root tears with a minimum 2-year follow-up. Radiographs were graded using Kellgren-Lawrence scores. Subanalysis was performed on 62 patients who underwent root repair. Tegner, Lysholm, International Knee Documentation Committee scores, and progression to arthroplasty were analyzed in the repair groups. Patient demographics, radiographic findings, and clinical outcomes were compared between medial meniscus posterior horn root tear (MMRT) and lateral meniscus root repair (LMRT). RESULTS: Of the 141 root tears, 109 were MMRTs, 30 were LMRTs, and 2 patients had both. At the time of injury, patients with MMRTs had a significantly higher age (MMRT = 51.4 vs LMRT=24.6, P < .0001), body mass index (MMRT = 32.1 vs LMRT 25.8, P < .0001), Kellgren-Lawrence score (MMRT = 1.3 vs LMRT=0.6, P < .0001), and higher rate of major meniscal extrusion (MMRT = 72% vs LMRT = 20%, P < .0001). Of the 30 LMRT, 30/30 (100.0%) were treated with meniscal repair. With MMRT, 52/109 (48%) were treated nonoperatively, 27/109 (25%) with partial meniscectomy, and 30/109 (27%) with meniscal repair. Sixty-two patients underwent meniscus root repair with an average 41-month follow-up. LMRT had significantly increased International Knee Documentation Committee (LMRT = 89.5, MMRT = 80.4, P = .02) and Tegner scores (LMRT = 6.5, MMRT = 5.1, P < .05) compared with MMRT. CONCLUSIONS: Compared with MMRTs, LMRTs occur in younger male patients with lower body mass index, less cartilage degeneration, less extrusion on magnetic resonance imaging, and more commonly with a ligament injury. Although good to excellent clinical outcomes were attained in select patients for both medial and lateral meniscus root repair, LMRTs may have better results after repair, suggesting that differences in injury and patient characteristics may contribute to differences in these outcomes. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

Isolated meniscus extrusion associated with meniscotibial ligament abnormality.

PURPOSE: The purpose of this study was to describe meniscus extrusion, present imaging characteristics, and provide clinical correlations for patients with isolated meniscus extrusion. METHODS: Of the 3244 MRI reports identified as having meniscus extrusion, 20 patients were identified to have isolated meniscus extrusion (0.62%). Patients with moderate to severe chondromalacia, meniscus tears, intra-articular fractures, tumours, and ligament tears were excluded. Radiographs were reviewed and graded using Kellgren-Lawrence (K-L) scores. MRI's were reviewed for the extent of extrusion and whether or not the meniscotibial ligament was intact. Clinical presentation and management were recorded. RESULTS: The study population consisted of 12 females and 8 males with a mean age of 40.5, diagnosed with meniscus extrusion and minimal concomitant knee pathology. 68% of patients were considered symptomatic as their knee pain correlated with the side of their meniscus extrusion and no other reason for pain was identified. The mean amount of meniscus extrusion was 2.5 mm (SD ± 1.1 mm) with 45% (9 of 20) having 3 + mm of extrusion. Meniscotibial ligament abnormality was identified in 65% of cases (13 of 20). Patients with 3 + mm of meniscus extrusion were much more likely to have associated meniscotibial ligament abnormality (100%, 9 of 9) compared to those with < 3 mm of extrusion (36%, 4 of 11) (RR 2.75, p = 0.048). The mean K-L grade obtained at the initial visit was 0.9 (95% CI 0.7-1.4) and the mean K-L grade obtained on final follow-up was 1.3 (95% CI 0.8-2.8) (n.s.) at a mean of 44.7 months. No correlation was found between K-L grade, gender, age, acute injury, and BMI in relation to meniscotibial ligament abnormality or amount of meniscal extrusion. CONCLUSIONS: Meniscus extrusion often occurs in the presence of significant knee pathology, predominantly with meniscus tears or osteoarthritis. Isolated meniscus extrusion is a rare occurrence that may present clinically with knee pain, commonly to the side in which the extrusion occurs. In patients with three or more millimetres of meniscus extrusion, an intact meniscus and minimal knee pathology, meniscotibial ligament abnormality is likely. This may provide an opportunity to treat the meniscotibial ligament abnormality with meniscus centralisation technique and decrease the amount of meniscus extrusion.

Meniscus repairs in the adolescent population-safe and reliable outcomes: a systematic review.

PURPOSE: The purpose of this study was to determine the outcomes of meniscus repair in the adolescent population, including: (1) failure and reoperation rates, (2) clinical and functional results, and (3) activity-related outcomes including return to sport. METHODS: Two authors independently searched MEDLINE, Cochrane Central Register of Controlled Trials & Cochrane Library, and CINHAL databases for literature related to meniscus repair in an adolescent population according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. No meta-analysis was performed in this qualitative systematic review. RESULTS: Thirteen studies, including no Level I, one Level II, one Level III, and eleven Level IV studies yielded 466 patients with 503 meniscus repairs. All defined meniscal re-tear as a primary endpoint, with a reported failure rate ranging from 0 to 42% at a follow-up ranging from 22 to 211 months. There were a total of 93 failed repairs. IKDC scores were reported in four studies with a mean improvement ranging from 24 to 42 (P < 0.001). Mean post-operative Lysholm scores were reported in seven studies, ranging from 85 to 96. Additionally, four of those studies provided mean pre-operative Lysholm scores, ranging from 56 to 79, with statistically significant mean score improvements ranging from 17 to 31. Mean post-operative Tegner Activity scores were reported in nine studies, with mean values ranging from 6.2 to 8. CONCLUSION: This systematic review demonstrates that both subjective and clinical outcomes, including failure rate, Lysholm, IKDC, and Tegner activity scale scores, are good to excellent following meniscal repair in the adolescent population. Further investigations should aim to isolate tear type, location, surgical technique, concomitant procedures, and rehabilitation protocols to overall rate of failure and clinical and functional outcomes. LEVEL OF EVIDENCE: IV.

No difference between single and staged posterolateral corner surgical procedures in the multiligament injured/dislocated knee.

PURPOSE: Posterolateral corner (PLC) injuries commonly occur in the setting of a dislocated knee and often require multiple procedures due to concomitant vascular, nerve, and soft tissue involvement. Debate persists regarding single vs staged surgery. The purpose of this study was to compare knee function after single and staged surgery for PLC injury. METHODS: Patients who underwent surgery for a PLC injury (KD I, IIIL, IV) with minimum follow-up of 2 years were included. Patients treated with staged and single surgery were matched according to age, sex, and KD grade. Lysholm and International Knee Documentation Committee (IKDC) subjective scores were obtained. Risk factors for poor knee function were assessed, including age, nerve, vascular, meniscal and articular cartilage injuries. RESULTS: Twenty single-surgery patients with a median age of 24 years (median follow-up 5.3 years, range 2-18.3) and 20 staged surgery patients with a median age of 26 years (median follow-up 4.3 years, range 2-19.8) were studied. The mean Lysholm score was 78.7 (± 20.3) in the single surgery and 84.2 (± 17.8) in the staged surgery cohort (n.s.). The mean IKDC score was 80.8 (± 21.1) in the single and 74.9 (± 18.9) in the staged surgery cohort (n.s.). Age at injury, peroneal, vascular, meniscal or cartilage injury were not associated with poor knee outcome. CONCLUSION: This study demonstrates similar knee function among patients with PLC injuries treated with single or staged surgical procedures. The need for staged surgery for the dislocated knee with PLC involvement should be individualized based on specific knee and patient-related factors. LEVEL OF EVIDENCE: III.

Total Knee Arthroplasty After Intramedullary Tibial Nail: A Matched Cohort Study.

BACKGROUND: As the use of intramedullary nails (IMNs) has become more common, there are an increasing number of patients requiring total knee arthroplasty (TKA) who have an indwelling tibial IMN. The purpose of this study is to compare implant survivorship, clinical outcomes, and complications in patients undergoing primary TKA with a history of tibial IMN to those without. METHODS: We retrospectively identified 24 TKAs performed between 2000 and 2017 after ipsilateral tibial IMN. Patients were matched 1:2 to patients undergoing primary TKA without history of tibial IMN based upon age, gender, body mass index, and year of surgery. Mean follow-up was 7 years. RESULTS: The 10-year survivorship free of any revision was 100% for the tibial IMN cohort, and 96% for the control cohort, while the 10-year survivorship free of any reoperation was 91% and 89%, respectively (P = .72). Patients with a history of tibial IMN had similar Knee Society Scores to matched controls at 2 years (P = .77) and 5 years (P = .09). Acquired idiopathic stiffness trended toward being more common (17% vs 6%, P = .21) and operative time trended toward being longer (135 vs 118 min, P = .07) when the tibial IMN was removed, but there was no overall difference in complication rate between cohorts. CONCLUSIONS: To our knowledge, this is the first report of primary TKA in patients with a history of ipsilateral tibial IMN. Compared to a matched cohort of patients without tibial IMN, these patients have similar outcomes in regards to implant survivorship, clinical outcomes, and risk of complications. LEVEL OF EVIDENCE: Therapeutic Level III.

Concussions in Ice Hockey - Moving Toward Objective Diagnoses and Point-of-care Treatment: A Review.

The incidence of sport-related concussion coupled with a doubling of the participation rate in youth hockey over the past two decades provides impetus for the review of the most promising concussion treatment options. This narrative review summarizes the future treatment options for sport-related concussions in ice hockey, while acknowledging their generalizability to concussion in all sports. Symptom assessment, sign observation, as well as cognitive and balance testing, have historically been used to diagnose a concussion. These methods continue to improve, but the need for effective treatments is clear. Pharmacologic, transcranial light, and nutritional supplement treatment options for concussion warranting further investigation have been identified. Dimethyl fumarate is an immunomodulatory compound thought to trigger antioxidant gene expression. Memantine reduces apoptosis and astrogliosis by inhibiting the calcium influx into cells normally caused by glutamate's activation of N-methyl-D-aspartate receptors. Thioredoxin-mimetic peptides and transcranial photobiomodulation temper the effects of the energy crisis by acting as free radical scavengers. In addition, seven neuroprotective nutritional supplements have been identified: berberine, creatine, curcumin, melatonin, omega-3 fatty acids, resveratrol, and vitamins. An estimated US $1.1 billion has been spent on unsuccessful traumatic brain injury clinical trials. As our ability to accurately diagnose concussion improves, dimethyl fumarate, memantine, thioredoxin-mimetic peptides, transcranial photobiomodulation, and nutritional supplements (berberine, creatine, curcumin, melatonin, omega-3 fatty acids, resveratrol, and vitamins) warrant further preclinical and clinical examination in advancing the treatment of sport-related concussions.