Clayton W. Nuelle

Hinged external fixation in the treatment of knee dislocations: a prospective randomized study.

BACKGROUND Our hypothesis was that patients treated with hinged external fixators as an adjunct to multiple-ligament reconstruction would have fewer reconstruction failures than patients treated without external fixation. METHODS In this prospective randomized study, patients with a knee dislocation either underwent ligament reconstruction with placement of an external hinged knee brace following surgery (Group A) or underwent ligament reconstruction with placement of a hinged external fixator (Compass Knee Hinge) for six weeks instead of the brace (Group B). The patients were followed clinically and were evaluated with physical examination, Lysholm and International Knee Documentation Committee knee scores, visual analog scale pain scores, and status regarding return to work and activities. RESULTS One hundred patients with 103 knee dislocations were enrolled. Seventy-seven patients with seventy-nine dislocations (thirty-two in Group A and forty-seven in Group B), with a minimum follow-up interval of twelve months, were available for evaluation. The mean duration of follow-up was thirty-nine months (range, twelve to eighty-six months). Nine patients (29%) in Group A had failed reconstructions compared with seven (15%) in Group B (p = 0.15). Group-A patients had twenty-two (21%) of 105 reconstructed individual ligaments fail compared with eleven (7%) of 157 reconstructed ligaments in Group B. The difference in ligament failure was significant (p < 0.001; power > 0.8), with more favorable results for the patients managed with the external fixation. CONCLUSIONS Hinged external fixation as a supplement to reconstruction following knee dislocation was associated with fewer failed ligament reconstructions compared with external bracing. Patients presenting with highly unstable knee dislocations should be considered for hinged external fixation to supplement initial reconstructive procedures.

Patient Factors, Donor Age, and Graft Storage Duration Affect Osteochondral Allograft Outcomes in Knees with or without Comorbidities

&NA; Limited data exists defining preoperative variables that affect outcomes after osteochondral allograft transplantation (OAT) in the knee. In this retrospective study, we examined 75 patients who underwent OAT for large (≥2 cm2) grade IV cartilage defects in the femoral condyle. Patient variables evaluated included the following: smoking, workers compensation, body mass index (BMI), pre‐injury activity level, number, and the type of co‐morbidities in the operated knee, lesion location and number of grafts placed. OCA donor age and graft storage duration from procurement were also evaluated. Preoperative and postoperative visual analogue scale (VAS) pain scores were the primary outcome measure. Overall, 53 patients (71%) had successful outcomes, with 81% of patients without co‐morbidities having successful outcomes. Active patients were significantly (p = 0.023) more likely to have a successful outcome than low activity patients. Patients with BMI <35 were 4 times more likely to have a successful outcome (p = 0.01). There were no significant differences based on donor age. Patients with transplanted grafts stored >28 days were significantly (p = 0.048) and 2.6 times more likely to have an unsuccessful outcome. This study provides new evidence for preoperative patient factors and graft variables that may influence the overall outcome after osteochondral transplantation in the knee.

Biomechanical Comparison of Five Posterior Cruciate Ligament Reconstruction Techniques

Abstract No surgical technique recreates native posterior cruciate ligament (PCL) biomechanics. We compared the biomechanics of five different PCL reconstruction techniques versus the native PCL. Cadaveric knees (n = 20) were randomly assigned to one of five reconstruction techniques: Single bundle all‐inside arthroscopic inlay, single bundle all‐inside suspensory fixation, single bundle arthroscopic‐assisted open onlay (SB‐ONL), double bundle arthroscopic‐assisted open inlay (DB‐INL), and double bundle all‐inside suspensory fixation (DB‐SUSP). Each specimen was potted and connected to a servo‐hydraulic load frame for testing in three conditions: PCL intact, PCL deficient, and PCL reconstructed. Testing consisted of a posterior force up to 100 N at a rate of 1 N/s at four knee flexion angles: 10, 30, 60, and 90 degrees. Three material properties were measured under each condition: load to 5 mm displacement, maximal displacement, and stiffness. Data were normalized to the native PCL, compared across techniques, compared with all PCL‐intact knees and to all PCL‐deficient knees using one‐way analysis of variance. For load to 5 mm displacement, intact knees required significantly (p < 0.03) more load at 30 degrees of flexion than all reconstructions except the DB‐SUSP. At 60 degrees of flexion, intact required significantly (p < 0.01) more load than all others except the SB‐ONL. At 90 degrees, intact, SB‐ONL, DB‐INL, and DB‐SUSP required significantly more load (p < 0.05). Maximal displacement testing showed the intact to have significantly (p < 0.02) less laxity than all others except the DB‐INL and DB‐SUSP at 60 degrees. At 90 degrees the intact showed significantly (p < 0.01) less laxity than all others except the DB‐SUSP. The intact was significantly stiffer than all others at 30 degrees (p < 0.03) and 60 degrees (p < 0.01). Finally, the intact was significantly (p < 0.05) stiffer than all others except the DB‐SUSP at 90 degrees. No technique matched the exact properties of the native PCL, but the double bundle reconstructions more closely recreated the native biomechanics immediately after implantation, with the DB‐SUSP coming closest to the native ligament. This study contributes new data for consideration in PCL reconstruction technique choice.

Biomechanical Comparison: Single-Bundle versus Double-Bundle Posterior Cruciate Ligament Reconstruction Techniques

&NA; Controversy exists regarding double‐bundle (DB) versus single‐bundle (SB) posterior cruciate ligament (PCL) reconstruction, with differences in multiple variables affecting biomechanical and clinical results. Our objective was to compare immediate postimplantation biomechanics of SB versus DB reconstructions to determine the relative importance of restoring both PCL bundles versus total graft volume. Twenty knees were randomly assigned to five techniques (n = 4 knees/technique), performed by three surgeons experienced in their technique(s), three SB techniques (n = 12; all‐inside arthroscopic inlay, all‐inside suspensory fixation, and arthroscopic‐assisted open onlay), and two DB techniques (n = 8; arthroscopic‐assisted open inlay and all‐inside suspensory fixation). Each knee was tested in three conditions: PCL‐intact, PCL‐deficient, and post‐PCL reconstruction. Testing consisted of a posterior‐directed force at four knee flexion angles, 10, 30, 60, and 90 degrees, to measure load to 5 mm of posterior displacement, maximum displacement (at 100 N load), and stiffness. Data for each knee were normalized, combined into two groups (SB and DB), and then compared using one‐way analysis of variance. Graft volumes were calculated and analyzed to determine if differences significantly influenced the biomechanical results. Intact knees were stiffer than both groups at most angles (p < 0.02; p < 0.05). DB was stiffer than SB at all angles except 30 degrees (p < 0.05). Intact knees had less laxity than SB (p < 0.03) and DB (p < 0.05) at 60 and 90 degrees. DB had less laxity than SB at all angles except 60 degrees (p < 0.05). Intact knees required more load than SB at 30, 60, and 90 degrees (p < 0.01) and more than DB at 60 and 90 degrees (p < 0.05). DB required more load than SB at 30, 60, and 90 degrees (p < 0.01). Graft volumes did not have strong correlations (r = 0.13–0.37) to any measurements. Neither group of PCL reconstruction techniques was able to replicate native PCL biomechanics. DB reconstructions were biomechanically superior to SB reconstructions; they may be preferred for clinical use when immediate post‐reconstruction graft strength and stability are critical. These results were not strongly influenced by graft size differences, further supporting the PCL codominance theory.

Osteochondral Autologous Transplantation

Osteochondral autologous transplantation (OAT) is a treatment strategy for small and medium sized focal articular cartilage defects in the knee. This article reviews the indications, surgical techniques, outcomes, and limitations of OAT for the management of symptomatic chondral and osteochondral lesions in the knee joint.

Patellofemoral anatomy and biomechanics.

Patellofemoral disorders are common. There is a broad spectrum of disease, ranging from patellofemoral pain and instability to focal cartilage disease and arthritis. Regardless of the specific condition, abnormal anatomy and biomechanics are often the root cause of patellofemoral dysfunction. A thorough understanding of normal patellofemoral anatomy and biomechanics is critical for the treating physician. Recognizing and addressing abnormal anatomy will optimize patellofemoral biomechanics and may ultimately translate into clinical success.

Incidence of Concurrent Peroneal Nerve Injury in Multiligament Knee Injuries and Outcomes after Knee Reconstruction

The purpose of this study was to determine incidence of concurrent peroneal nerve injury and to compare outcomes in patients with and without peroneal nerve injury after surgical treatment for multiligament knee injuries (MLKIs). A retrospective study of 357 MLKIs was conducted. Patients with two or more knee ligaments requiring surgical reconstruction were included. Mean follow-up was 35 months (0-117). Incidence of concurrent peroneal nerve injury was noted and patients with and without nerve injury were evaluated for outcomes. Concurrent peroneal nerve injury occurred in 68 patients (19%). In patients with nerve injury, 45 (73%) returned to full duty at work; 193 (81%) patients without nerve injury returned to full duty (p = 0.06). In patients with nerve injury, 37 (60%) returned to their previous level of activity; 148 (62%) patients without nerve injury returned to their previous level of activity (p = 0.41). At final follow-up, there were no significant differences in level of pain (mean visual analog scale 1.6 vs. 2; p = 0.17), Lysholm score (mean 88.6 vs. 88.8; p = 0.94), or International Knee Documentation Committee score (mean 46.2 vs. 47.8; p = 0.67) for patients with or without peroneal nerve injury, respectively. Postoperative range of motion (ROM) (mean 121 degrees) was significantly lower (p = 0.02) for patients with nerve injury compared with patients without nerve injury (mean 127 degrees). Concurrent peroneal nerve injury occurred in 19% of patients in this large cohort suffering MLKIs. After knee reconstruction surgery, patients with concurrent peroneal nerve injuries had significantly lower knee ROM and trended toward a lower rate of return to work. However, outcomes with respect to activity level, pain, and function were not significantly different between the two groups. This study contributes to our understanding of patient outcomes in patients with concurrent MLKI and peroneal nerve injury, with a focus on the patients ability to return to work and sporting activity.

In vitro toxicity of local anaesthetics and corticosteroids on supraspinatus tenocyte viability and metabolism

Summary Background/Objective The purpose of this study was to evaluate supraspinatus tenocyte viability and metabolism in explants exposed to various local anaesthetics and corticosteroids. Our hypothesis was that the tendons exposed to these common injectates would have significantly decreased cell viability and metabolism compared with controls. Methods Supraspinatus tendon explants were obtained from dogs, placed in a culture media, and randomly assigned to one of the following groups: culture media only (control), 1% lidocaine, 0.5% lidocaine, 0.25% bupivacaine, 0.125% bupivacaine, 0.0625% bupivacaine, betamethasone acetate (5 mg), methylprednisolone acetate (40 mg), or triamcinolone acetonide (40 mg). Cell viability was determined on Days 1 and 7 after culture treatment using calcein AM (live cell) and Sytox Blue (dead cell) stains. Tissue metabolism was assessed on Days 1 and 7 using the resazurin blue metabolic assay. Significant differences were evaluated using a one-way analysis of variance with Tukey post hoc analysis. Results Compared with the controls, there were significant decreases in cell viability noted at Days 1 and 7 in tenocytes exposed to 1% lidocaine, betamethasone, and methylprednisolone. Significant decreases in cell metabolism were also noted at Days 1 and 7 in those groups. Treatment with 0.125% bupivacaine, 0.0625% bupivacaine, and triamcinolone demonstrated no decrease in cell viability or metabolism when compared with controls at any time point. Conclusion This data confirms that peritendinous injection of commonly used local anaesthetics and corticosteroids results in significant supraspinatus tenotoxicity in vitro. Further in vivo studies are required before making definitive clinical recommendations.

Internal Fixation of Osteochondritis Dissecans Lesions in the Patellofemoral Joint

Abstract Osteochondritis dissecans (OCD) lesions of the patellofemoral joint can be difficult to identify and treat. Asymptomatic or stable lesions in skeletally immature patients may be treated nonoperatively, but symptomatic lesions often require surgical intervention. Evidence of instability should be carefully evaluated with preoperative magnetic resonance imaging or computed tomography arthrogram. Careful preoperative planning is necessary to ensure the appropriate surgical approach and implants are selected for surgical management. Multiple techniques have been described, but internal fixation of both “classic” and cartilage‐only OCD lesions has been shown to have strong outcomes in managing these difficult cases.

Patient Factors Associated with Osteochondral Allograft Success in Knees with or without Co-morbidities

Objectives: To determine preoperative variables that may influence outcomes after osteochondral allograft transplantation for treatment of large cartilage defects in the knee. Methods: A retrospective review of 75 patients who underwent osteochondral allograft transplantation for large (>1 cm) grade IV cartilage defects in knees was performed. Patient variables evaluated included: smoking, workers compensation, BMI, pre-injury activity level (high level athlete, recreational athlete, active non-athlete, minimal activity, sedentary), number and type of co-morbidities in the operated knee (meniscal, ligament, and/or other cartilage pathology), lesion location (medial femoral condyle, lateral femoral condyle or multiple lesions), number of grafts placed (1, 2 or >2) and patients who underwent revision surgery related to OCA transplantation. Preoperative and postoperative VAS pain scores were used as the primary outcome measure. Success was defined as a VAS pain score of 0 or improvement in score (decrease) of 2 or more at final follow-up. The mean follow-up time was 19.5 months (3-53 months). Statistically significant (p<0.05) effects on successful outcomes were evaluated using Fishers exact tests and odds ratios. Results: The study population was 41 males and 34 females with an average age of 34.2 years (14-61). 53 patients (71%) had successful outcomes. 59 patients (79%) had co-morbidities with the average being 2 comorbidities (1-4) per patient. 68% of patients with co-morbidities achieved a successful outcome versus 81% of patients with no co-morbidities, but this difference in proportions was not statistically significant (p=0.46). Active patients (HLA, REC, ACT) were significantly (p=0.023) and 4.5 times more likely to have a successful outcome than minimally active or sedentary patients. Patients with BMI <30 were 3.7 times more likely to have a successful result and the difference was significant (p=0.011). Smoking, workmans compensation, OCA-related revision surgery, lesion location and number of grafts placed did not have statistically significant effects on outcome. Conclusion: Osteochondral allograft transplantation can be a successful treatment option for large cartilage defects in the knee with patients having no intra-articular co-morbidities achieving an 81% success rate. Patients who are more active preoperatively and those with BMI <30 were significantly more likely to have successful outcomes.