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Featured researches published by Nick R. Johnson.


Clinical Orthopaedics and Related Research | 2017

Hamstring Autograft versus Patellar Tendon Autograft for ACL Reconstruction: Is There a Difference in Graft Failure Rate? A Meta-analysis of 47,613 Patients

Brian T. Samuelsen; Kate E. Webster; Nick R. Johnson; Timothy E. Hewett; Aaron J. Krych

BackgroundBone-patellar tendon-bone (bone-tendon-bone) and four-strand hamstring tendon grafts (hamstring) are the most commonly utilized autografts for primary anterior cruciate ligament (ACL) reconstruction. Existing clinical trials, registry studies, and meta-analyses offer conflicting opinions regarding the most favorable graft choice.Questions/purposesWhich graft type for ACL reconstruction (bone-tendon-bone or hamstring) has a higher risk of (1) graft rupture and/or (2) graft laxity?MethodsWe performed a meta-analysis of randomized controlled trials (RCTs), prospective cohort studies, and high-quality national registry studies to compare the outcomes of primary ACL reconstruction with bone-tendon-bone autograft or hamstring autograft. Studies that compared these graft types were identified through a comprehensive search of electronic databases (PubMed, MEDLINE, EMBASE, and the Cochrane Library). Two independent reviewers utilized the Jadad scale for RCT study quality and the Modified Coleman Methodology Score for prospective comparative and registry study quality. The included studies were analyzed for the primary outcome measure of graft rupture with or without revision ACL surgery. In surviving grafts, secondary outcomes of graft laxity were quantified by KT1000/2000™ testing, a positive pivot shift test, and a positive Lachman test. Meta-analysis was performed with Review Manager. A total of 47,613 ACL reconstructions (39,768 bone-tendon-bone and 7845 hamstring) from 14 RCTs, 10 prospective comparative studies, and one high-quality national registry study were included in this meta-analysis. Mean age was 28 years in both groups. Sixty-three percent of patients in the bone-tendon-bone cohort were men versus 57% of patients in the hamstring cohort. Mean followup was 68 ± 55 months.ResultsTwo hundred twelve of 7560 (2.80%) bone-tendon-bone grafts ruptured compared with 1123 of 39,510 (2.84%) in the hamstring group (odds ratio = 0.83, 95% confidence interval, 0.72-0.96; p = 0.01). The number needed to treat analysis found that 235 patients would need to be treated with a bone-tendon-bone graft over a hamstring tendon graft to prevent one graft rupture. Instrumented laxity analysis showed that 22% (318 of 1433) of patients in the bone-tendon-bone group had laxity compared with 18% (869 of 4783) in the hamstring tendon group (odds ratio = 0.86; p = 0.16). Pivot shift analysis showed a positive pivot shift in 19% (291 of 1508) of the bone-tendon-bone group compared with 17% (844 of 5062) in the hamstring group (odds ratio = 0.89; p = 0.51). Lachman testing showed a positive Lachman in 25% (71 of 280) of patients receiving bone-tendon-bone grafts compared with 25% (73 of 288) in the hamstring group (odds ratio = 0.96; p = 0.84).ConclusionsIn this meta-analysis of short- to mid-term followup after primary ACL reconstruction, hamstring autografts failed at a higher rate than bone-tendon-bone autografts. However, failure rates were low in each group, the difference observed was small, and we observed few differences between graft types in terms of laxity. Both graft types remain viable options for primary ACL reconstruction, and the difference in failure rate should be one part of a larger conversation with each individual patient about graft selection that should also include potential differences in donor site morbidity, complication rates, and patient-reported outcome measures. Continued prospective collection of patient data will be important going forward as we attempt to further characterize the potential differences in outcomes attributable to graft selection.Level of EvidenceLevel III, therapeutic study.


Orthopaedic Journal of Sports Medicine | 2017

Nonoperative Management of Osteochondritis Dissecans of the Knee: Progression to Osteoarthritis and Arthroplasty at Mean 13-Year Follow-up:

Thomas L. Sanders; Ayoosh Pareek; Nick R. Johnson; James L. Carey; Travis G. Maak; Michael J. Stuart; Aaron J. Krych

Background: Osteochondritis dissecans (OCD) is a disorder of subchondral bone that commonly affects the knee. Purpose: To (1) evaluate the rate of arthritis and knee arthroplasty in a population-based cohort of patients with OCD lesions treated nonoperatively and (2) evaluate factors that may predispose patients to knee osteoarthritis and arthroplasty. Study Design: Case series; Level of evidence, 4. Methods: Eighty-six patients (mean age, 21.4 years) with OCD lesions treated nonoperatively were identified between 1976 and 2014. Information related to the diagnosis, laterality of lesion, details of treatment, and progression to arthritis was obtained from the medical record. Factors predictive of arthritis and arthroplasty (age, sex, body mass index [BMI], and lesion location) were examined. Results: At a mean ± SD follow-up of 12.6 ± 9.8 years from diagnosis, 13 patients (15%) were diagnosed with arthritis, corresponding to a cumulative incidence of 5.0% at 5 years, 10.0% at 10 years, 20.0% at 25 years, and 30.0% at 35 years. The cumulative incidence of arthroplasty was 1.0% at 5 years, 3.0% at 10 years, 8.0% at 25 years, and 8.0% at 35 years. BMI at diagnosis greater than 25 kg/m2 (hazard ratio [HR], 15.4; 95% CI, 1.9-124.5), patellar OCD lesions (HR, 15.0; 95% CI, 1.3-345.3), and diagnosis as an adult (HR, 21.7; 95% CI, 2.7-176.3) were factors associated with an increased risk of arthritis. Conclusion: Arthritis after nonoperative treatment of OCD lesions is a challenging problem, with an estimated 30% cumulative incidence at 35 years after diagnosis. In contrast, the long-term rate of arthroplasty is low. BMI at diagnosis greater than 25 kg/m2 and patellar OCD lesions are predisposing factors for arthritis. Diagnosis of OCD as an adult was associated with a greater risk of arthritis.


American Journal of Sports Medicine | 2018

Is Treatment of Segond Fracture Necessary With Combined Anterior Cruciate Ligament Reconstruction? Response

Aaron J. Krych; Heath P. Melugin; Nick R. Johnson; Isabella T. Wu; Bruce A. Levy; Michael J. Stuart

Background: There is a paucity of clinical information to guide the treatment of a combined anterior cruciate ligament (ACL) tear and Segond fracture. Purpose: To compare clinical outcomes, graft failure rates, and activity levels between patients undergoing ACL reconstruction (ACLR) with and without an untreated Segond fracture at a minimum 2-year follow-up. Study Design: Cohort study; Level of evidence, 3. Methods: This study included a group of patients with a combined ACL tear/untreated Segond fracture that was matched based on age, sex, body mass index, and graft type to a control group of patients with an ACL tear and no Segond fracture. All patients were treated with ACLR alone between the years of 2000 and 2015. The diagnosis of a Segond fracture, or bony avulsion of the anterolateral complex, was made by radiographic analysis. Data regarding the initial injury, surgical intervention, and physical examination findings were recorded. Clinical and functional outcomes were obtained using physical examination results, International Knee Documentation Committee (IKDC) subjective scores, and Tegner activity levels. Results: Twenty patients (16 male, 4 female) with a combined ACL tear/untreated Segond fracture with a mean age of 26.3 years (range, 13-44 years) were matched to a control group of 40 patients (32 male, 8 female) with an ACL tear and no Segond fracture with a mean age of 26.4 years (range, 13-47 years). The study group was followed for a mean of 59.1 months (range, 24-180 months) and the control group for a mean of 55.5 months (range, 24-120 months). The mean IKDC score was 86.5 (range, 54-100) for the study group compared with 93.0 (range, 54-100) for the control group (P = .03). The graft rupture rate was 10% for both groups (P = .97). The mean time to rupture was 33.0 months (range, 21-45 months) in the study group and 63.5 months (range, 39-88 months) in the control group (P = .24). Patients in the study group had significantly more anteroposterior instability by preoperative Lachman testing than those in the control group (control group: 0 normal, 3 grade 1+, 37 grade 2+, 0 grade 3+; study group: 0 normal, 1 grade 1+, 10 grade 2+, 9 grade 3+; P = .0001). There was no significant difference between the 2 groups in regard to postoperative Lachman testing (control group: 35 normal, 3 grade 1+, 2 grade 2+, 0 grade 3+; study group: 17 normal, 3 grade 1+, 0 grade 2+, 0 grade 3+; P = .31). Patients in the study group had significantly more instability by preoperative pivot-shift testing than those in the control group (control group: 0 normal, 7 grade 1+, 33 grade 2+, 0 grade 3+; study group: 1 normal, 1 grade 1+, 11 grade 2+, 7 grade 3+; P = .0003). No significant difference was found between the 2 groups for postoperative pivot-shift testing (control group: 36 normal, 2 grade 1+, 2 grade 2+, 0 grade 3+; study group: 18 normal, 1 grade 1+, 1 grade 2+, 0 grade 3+; P = .61) or final Tegner activity level (median, 6). Conclusion: At midterm follow-up, patients undergoing ACLR with and without a Segond fracture had similar pivot-shift test results, graft failure rates, and activity levels. The IKDC score was statistically worse in the patients with a combined ACL tear/untreated Segond fracture, but the difference was less than the minimal clinically important difference for the IKDC score. These findings suggest that patients with a combined ACL tear/untreated Segond fracture can have comparable outcomes to patients with an ACL tear and no Segond fracture when treated with ACLR alone.


American Journal of Sports Medicine | 2018

Multicenter Analysis of Midterm Clinical Outcomes of Arthroscopic Labral Repair in the Hip: Minimum 5-Year Follow-up

Mario Hevesi; Aaron J. Krych; Nick R. Johnson; John M. Redmond; David E. Hartigan; Bruce A. Levy; Benjamin G. Domb

Background: The technique of hip arthroscopic surgery is advancing and becoming more commonly performed. However, most current reported results are limited to short-term follow-up, and therefore, the durability of the procedure is largely unknown. Purpose: To perform a multicenter analysis of mid-term clinical outcomes of arthroscopic hip labral repair and determine the risk factors for patient outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: Prospectively collected data of primary hip arthroscopic labral repair performed at 4 high-volume centers between 2008 and 2011 were reviewed retrospectively. Patients were assessed preoperatively and postoperatively with the visual analog scale (VAS), modified Harris Hip Score (mHHS), and Hip Outcome Score–Sports-Specific Subscale (HOS-SSS) at a minimum of 5 years’ follow-up. Factors including age, body mass index (BMI), Tönnis grade, and cartilage grade were analyzed in relation to outcome scores, and revision rates were determined. Failure was defined as subsequent ipsilateral hip surgery, including revision arthroscopic surgery and open hip surgery. Results: A total of 303 patients (101 male, 202 female) with a mean age of 32.0 years (range, 10.7-58.9 years) were followed for a mean of 5.7 years (range, 5.0-7.9 years). Patients achieved mean improvements in VAS of 3.5 points, mHHS of 20.1 points, and HOS-SSS of 29.3 points. Thirty-seven patients (12.2%) underwent revision arthroscopic surgery, and 12 (4.0%) underwent periacetabular osteotomy, resurfacing, or total hip arthroplasty during the study period. Patients with a BMI >30 kg/m2 had a mean mHHS score 9.5 points lower and a mean HOS-SSS score 15.9 points lower than those with a BMI ≤30 kg/m2 (P < .01). Patients aged >35 years at surgery had a mean mHHS score 4.5 points lower and a HOS-SSS score 6.7 points lower than those aged ≤35 years (P = .03). Patients with Tönnis grade 2 radiographs demonstrated a 12.5-point worse mHHS score (P = .02) and a 23.0-point worse HOS-SSS score (P < .01) when compared with patients with Tönnis grade 0. Conclusion: Patients demonstrated significant improvements in VAS, mHHS, and HOS-SSS scores after arthroscopic labral repair. However, those with Tönnis grade 2 changes preoperatively, BMI >30 kg/m2, and age >35 years at the time of surgery demonstrated significantly decreased mHHS and HOS-SSS scores at final follow-up.


Orthopaedic Journal of Sports Medicine | 2018

Medial Patellofemoral Ligament Reconstruction Reduces Radiographic Measures of Patella Alta in Adults

Jarret M. Woodmass; Nick R. Johnson; Robert A. Cates; Aaron J. Krych; Michael J. Stuart; Diane L. Dahm

Background: Patellar height has long been considered a risk factor for patellofemoral instability. However, recent pediatric literature demonstrated a reduction in patellar height measurements following medial patellofemoral ligament (MPFL) reconstruction. Purpose: To assess the mean change in patellar height and the percentage of skeletally mature patients with patellar height ratios reduced to within-normal limits following MPFL reconstruction. Study Design: Case series; Level of evidence, 4. Methods: Adult patients undergoing primary MPFL reconstruction for recurrent lateral patellar instability between 2005 and 2013 were identified. Pre- and postoperative (within 1 year of surgery) lateral knee radiographs were assessed for patellar height indices, including Caton-Deschamps, Blackburne-Peel, and Insall-Salvati ratios. The change in patellar height and the number of patients reduced from abnormal to normal patellar height ratios following MPFL reconstruction were assessed. Results: Overall, 32 adult patients were included in the study, with a mean age of 25.7 years (range, 18-55 years). There were 21 women (66%) and 11 men (34%). Insall-Salvati, Blackburne-Peel, and Caton-Deschamps ratios all demonstrated significant reductions in patellar height between pre- and postoperative lateral knee radiographs (P < .001). All 3 indices showed a reduction in the number of patients meeting the criteria for patella alta following MPFL reconstruction. A total of 64% of patients had an abnormal preoperative Caton-Deschamps ratio reduced to within normal limits postoperatively. Conclusion: MPFL reconstruction provides a consistent reduction in patellar height measurements. The Caton-Deschamps ratio was reduced to the reference range following MPFL reconstruction in 64% of patients with preoperative patella alta. Surgeons treating patellofemoral instability should expect a reduction in patellar height after ligament reconstruction, which may affect the need for more invasive distalization procedures.


Orthopaedic Journal of Sports Medicine | 2017

Operative Management of Osteochondritis Dissecans: Progression to Osteoarthritis and Arthroplasty in a Population Based Cohort

Thomas L. Sanders; Ayoosh Pareek; Nick R. Johnson; Rohith Mohan; James L. Carey; Michael J. Stuart; Aaron J. Krych

Objectives: Osteochondritis dissecans (OCD) is a disorder of subchondral bone that causes adverse effects on the overlying cartilage and commonly affects the knee. The purpose of this study is to (1) evaluate the rate of arthritis and knee arthroplasty in a population-based cohort of patients with OCD lesions treated operatively and (2) evaluate factors that may predispose patients to knee osteoarthritis and arthroplasty. Methods: 221 patients (mean age 26.1 ± 13.6 years) with OCD lesions treated operatively were identified between 1976 and 2014 and followed for a mean of 16.3 (±11.4) years from diagnosis. Information related to the diagnosis, laterality of lesion, details of treatment, and progression to arthritis was obtained from the medical record. Surgical treatment was classified as palliative (fragment excision) or restorative (lesion drilling, fragment fixation, osteochondral allograft or autograft). Factors predictive of arthritis and arthroplasty were examined. Results: In the palliative group, the cumulative incidence of arthritis was 12.0% at 5 years, 17.0% at 10 years, 26.0% at 15 years, 39.0% at 20 years, and 70% at 30 years. The cumulative incidence of arthroplasty was 2.0% at 5 years, 4.0% at 10 years, 4.0% at 15 years, 10.0% at 20 years, and 32.0% at 30 years. In the restorative group, the cumulative incidence of arthritis was 3.0% at 5 years, 7.0% at 10 years, 16.0% at 15 years, 25.0% at 20 years, and 51% at 30 years. The cumulative incidence of arthroplasty was 0.0% at 5 years, 0.0% at 10 years, 3.0% at 15 years, 6.0% at 20 years, and 11.0% at 30 years. BMI greater than 25 kg/m2 (HR 3.3, 95% CI: 1.6, 7.0), older age at diagnosis (HR 4.9, 95% CI: 1.8, 17.3) and fragment excision (HR 2.3, 95% CI: 1.2, 4.6) were predictive of arthritis. Conclusion: OCD patients treated with fragment excision have a high rate of arthritis and knee arthroplasty at long-term follow-up. In contrast, patients treated with fragment repair or osteochondral restoration have lower rates of arthritis and arthroplasty. BMI greater than 25 kg/m2, older age at diagnosis, and fragment excision were predictive of arthritis.


Journal of Knee Surgery | 2017

Arthritis Progression on Serial MRIs Following Diagnosis of Medial Meniscal Posterior Horn Root Tear.

Aaron J. Krych; Nick R. Johnson; Rohith Mohan; Mario Hevesi; Michael J. Stuart; Laurel A. Littrell; Mark S. Collins

&NA; Medial meniscus posterior root tears (MMPRTs) are a significant source of pain and dysfunction. The purpose of this study was to evaluate changes in the medial compartment of the knee over time following the diagnosis of a MMPRT on MRI. A retrospective review of the institutional database was performed for patients with an initial MRI diagnosis of a MMPRT. Patients were included if they had a subsequent follow‐up MRI on the same knee. Patients with surgical intervention, including debridement or repair, were excluded. MRIs were evaluated by two board‐certified musculoskeletal radiologists. MMPRTs were defined using the LaPrade classification, and the medial compartment articular cartilage was graded using the modified Outerbridge classification. MRIs were reviewed for meniscus extrusion, subchondral bone edema, and insufficiency fractures. Patients were divided into two groups for the analysis to account for differences in MRI time intervals. Group 1 had a follow‐up MRI within 12 months of initial imaging (subacute group) and Group 2 had a follow‐up MRI greater than 12 months after initial imaging (chronic group). Forty‐one knees and 82 MRIs were analyzed, including 20 knees/40 MRIs (13 females, 7 males) in the subacute group and 21 knees/42 MRIs (14 females, 7 males) in the chronic group. Subacute patients had a mean age of 59.5 ± 8.8 years and a mean interval of 4.8 ± 2.6 months between MRIs compared with 53.6 ± 11.0 years and 38.2 ± 20.8 months, respectively, for the chronic group. Meniscal extrusion, femoral modified Outerbridge grade, and tibial modified Outerbridge grade worsened between initial and final MRI in both groups (p < 0.05). In both groups, there were no significant differences between initial and final MRIs with regard to the LaPrade classification, insufficiency fracture, or subchondral cysts of the tibia. Progressive meniscus extrusion and medial compartment articular cartilage degeneration were seen in patients with MMPRTs within a year from diagnosis.


Arthroscopy techniques | 2017

Lateral Meniscus Allograft Transplantation: The Bone Plug Technique

Jarret M. Woodmass; Nick R. Johnson; Bruce A. Levy; Michael J. Stuart; Aaron J. Krych

Lateral meniscus tears are commonly encountered by orthopaedic surgeons. Despite efforts to repair and preserve the meniscus, meniscectomy is occasionally required to treat irreparable tears. The resulting lateral meniscus deficiency leads to increased tibiofemoral contact pressures and ultimately early osteoarthritic changes in the knee. Lateral meniscal allograft transplant (LMAT) has been proposed as a way to restore the lateral meniscus–deficient knee to its native form. Although several techniques for LMAT have been proposed, osseous fixation has demonstrated increased stability, improved outcomes, and improved long-term survival. This article presents a technique for LMAT using bone plugs and standard arthroscopic portals.


Orthopaedic Journal of Sports Medicine | 2018

Non-operative Management of Posterior Shoulder Instability: An Assessment of Survival and Predictors for Conversion to Surgery at 1 to 13 Years After Diagnosis

Jarret M. Woodmass; Julia Lee; Nick R. Johnson; Christopher L. Camp; Diane L. Dahm; Aaron J. Krych

Objectives: Among patients treated non-operatively for 1 year following a diagnosis of posterior shoulder instability (PSI), little is known about the the incidence of surgery between 1-13 years after injury. The purpose of this study is to define the frequency and evaluate the factors predictive for late surgical intervention of symptomatic PSI. Methods: This study included a population-based cohort of 115 patients (14 females, 101 males) diagnosed with PSI between January 1994 and July 2012 with a minimum 5-years follow-up (mean:13.9 years; range: 5-23 years). Landmark survival analysis was performed to evaluate incidence of surgery after 1 year. Survival was estimated using Kaplan Meier method and predictors of late surgical intervention were analyzed using Cox proportional hazards regression. Results: A total of 61/115 (53%) patients were treated non-operatively for 1 year following diagnosis of PSI. Of these, 24/61 (39%) converted to surgery for symptomatic PSI. The overall survival free of surgery at 1 and 5 years was 53.0% (95% CI 434.7-63.0) and 37.1% (95% CI 29.1-47.1), respectively. BMI >35 (p=0.04, HR 3.3) was predictive for late conversion to surgery. Age, gender, occupation, or history of glenohumeral dislocation were not significant. Assessing surgery as a time dependent covariate, a patient undergoing surgery was at an increased risk for radiographic progression of osteoarthritis (p=0.02, HR=4.0, 95% CI 1.2-13.2). Conclusion: Conservative management was performed for at least one year in over half of patients diagnosed with PSI. However, long-term follow-up demonstrates that nearly 40% of these patients eventually require surgery. Increased BMI was predictive for late failure of while age, gender, history of dislocation and occupation did not show an effect. Patients who underwent surgery were at an increased risk of radiographic progression of arthritis.


Journal of Knee Surgery | 2018

Posterolateral Corner Reconstruction using the Anatomical Two-Tailed Graft Technique: Clinical Outcomes in the Multiligament Injured Knee

Jarret M. Woodmass; Thomas L. Sanders; Nick R. Johnson; Isabella T. Wu; Aaron J. Krych; Michael J. Stuart; Bruce A. Levy

&NA; Injury to the posterolateral corner (PLC) of the knee can lead to both varus and rotational instability. Multiple PLC reconstruction techniques have been described, including one‐tailed graft (fibula‐based constructs) or two‐tailed graft (combined fibula‐ and tibia‐based constructs). The purpose of our study was to evaluate the clinical outcomes of anatomical two‐tailed graft reconstruction of the PLC in the setting of multiligament knee injuries (MKLIs) with grade III varus instability. Patients were identified through a prospective MLKI database between 2004 and 2013. Patients who received fibular collateral ligament and PLC reconstructions using a two‐tailed graft and had a minimum follow‐up of 2 years were included. Patients were assessed for clinical laxity grade, range of motion, and functional outcomes using Lysholm and International Knee Documentation Committee (IKDC) scores. Twenty patients (16 male, 4 female) with a mean age of 30.7 (range: 16‐52) and a mean follow‐up of 52.2 months (range: 24‐93 months) were included. Knee dislocation (KD) grades included: 4 KD‐1, 10 KD 3‐L, 5 KD‐4, and 1 KD‐5. No patients had isolated PLC injuries. Mean IKDC and Lysholm score were 73.1 ± 25.8 and 78 ± 26, respectively. Mean range of motion was ‐1.1 to 122.8. In full extension, two patients (10%) had grade 1 laxity to varus stress. In 30 degrees of knee flexion, five (25%) patients had grade 1 laxity, and two (10%) had grade 2 laxity. Anatomical two‐tailed PLC reconstruction can reliably restore varus stability when performed on patients with MLKIs and type C posterolateral instability with hyperextension external rotation recurvatum deformity. Satisfactory functional outcome scores were achieved in the majority of patients. This study supports the use of an anatomical two‐tailed PLC reconstruction in the multiligament injured knee. The level of evidence is IV, case series.

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James L. Carey

University of Pennsylvania

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