Patrick E. Greis

Revision Anterior Cruciate Ligament Reconstruction

Revision reconstruction of the anterior cruciate ligament (ACL) introduces several diagnostic and technical challenges in comparison with primary ACL reconstruction. With the increasing numbers of original reconstructions combined with the continued expectation of high-level athletic participation, revision ACL reconstruction is likely to become more frequent. The purpose of this article was to summarize the causes of failure and the evaluation of the patient with recurrent instability. A review of the literature regarding results after revision ACL reconstruction was performed to assist in the decision-making process and patient counseling. Good results can be obtained in terms of functional stability after revision reconstruction, but chondral and meniscal injury as well as unrecognized associated pathologic instability may play a role in diminished outcomes. In addition, a wide variety of surgical techniques are reviewed to address problems associated with tunnel malposition, widening, and pre-existing hardware.

Meniscal Injury: I. Basic Science and Evaluation

The patient with meniscal injury may present with pain, swelling, or mechanical symptoms and often requires surgical intervention for symptom resolution. Treatment of such injuries relies on understanding the gross and microanatomic features of the meniscus that are important in maintaining meniscal function. The ability of the meniscus to participate in load bearing, shock absorption, joint lubrication, and joint stability depends on the maintenance of its structural integrity. The diagnosis of meniscal injury often can be made by clinical evaluation utilizing the history, physical examination, and plain radiographs. Magnetic resonance imaging can be useful in confirming the diagnosis when clinical findings are inconclusive. Treatment depends on tear pattern, vascularity, and an assessment of tissue quality. Surgical decision making for the treatment of meniscal injury is based on patient factors and understanding of the meniscal structure, function, and pathology.

A Prospective Randomized Clinical Trial Comparing Arthroscopic Single- and Double-Row Rotator Cuff Repair Magnetic Resonance Imaging and Early Clinical Evaluation

Background Double-row arthroscopic rotator cuff repair has become more popular, and some studies have shown better footprint coverage and improved biomechanics of the repair. Hypothesis Double-row rotator cuff repair leads to superior cuff integrity and early clinical results compared with single-row repair. Study Design Randomized controlled trial; Level of evidence, 1. Methods Forty patients were randomized to either single-row or double-row rotator cuff repair at the time of surgical intervention. Patients were followed with clinical measures (UCLA, Constant, WORC, SANE, ASES, as well as range of motion, internal rotation strength, and external rotation strength). Magnetic resonance imaging (MRI) studies were performed on each shoulder preoperatively, 6 weeks, 3 months, and 1 year after repair. Results Mean anteroposterior tear size by MRI was 1.8 cm. A mean of 2.25 anchors for single row (SR) and 3.2 for double row (DR) were used. There were 2 retears at 1 year in each group. There were 2 additional cases that had severe thinning in the DR repair group at 1 year. The MRI measurements of footprint coverage, tendon thickness, and tendon signal showed no significant differences between the 2 repair groups. At 1 year, there were no differences in any of the postoperative measures of motion or strength. At 1 year, mean WORC (SR, 84.8; DR, 87.9), Constant (SR, 77.8; DR, 74.4), ASES (SR, 85.9; DR, 85.5), UCLA (SR, 28.6; DR, 29.5), and SANE (SR, 90.9; DR, 89.9) scores showed no significant differences between groups. Conclusions No clinical or MRI differences were seen between patients repaired with a SR or DR technique.

Outpatient management of continuous peripheral nerve catheters placed using ultrasound guidance: an experience in 620 patients.

BACKGROUND:Continuous peripheral nerve block (CPNB) is an optimal choice for analgesia after orthopedic procedures, but is not commonly used in outpatients because of concern regarding the possibility of catheter-related complications. In addition, it may be difficult to provide adequate patient access to physicians in this setting. We present 620 outpatients who were treated with CPNB using an established protocol. METHODS:All catheters were placed using direct ultrasound visualization. These patients received extensive oral and written preoperative instruction and were provided continuous telephone access to the anesthesiologist during the postoperative period. All patients were also contacted at home by telephone on the first postoperative day. In addition, each patient was seen and examined by the surgeon within 2 wk of hospital discharge. RESULTS:Of the 620 patients, there were 190 interscalene (brachial plexus), 206 fascia iliaca (femoral nerve), and 224 popliteal fossa (sciatic nerve) catheters. Two patients (0.3%) had complications related to the nerve block. In both of these patients, the symptoms resolved within 6 wk of surgery. Twenty-six patients (4.2%) required postoperative interventions by the anesthesiologist. One patient returned to the hospital for catheter removal. CONCLUSIONS:In this large series of outpatients treated with CPNB, there were surprisingly few interventions requiring an anesthesiologist. Likewise, patients were able to manage and remove their catheters at home without additional follow-up. This suggests that with adequate instruction and telephone access to health care providers, patients are comfortable with managing and removing CPNB catheters at home.

Anatomy and biomechanics of the anterior cruciate ligament.

This article reviews the literature on embryology, anatomy, function, and biomechanics to define the properties of the native ACL. The discussion focuses on the ligamentous architecture and gross anatomy of the ACL including its femoral and tibial insertions as well as its midsubstance passing through the intercondylar fossa. Biomechanical modeling, mechanical and structural properties, and function of the ACL as a primary and secondary stabilizer under non-weightbearing and weightbearing conditions are described.

Treatment of Postoperative Anterior Cruciate Ligament Infections with Graft Removal and Early Reimplantation

Background Septic arthritis after arthroscopic anterior cruciate ligament reconstruction is rare, and the most appropriate treatment is unclear. Current recommendations are that, if the graft is removed, reimplantation should be delayed for 6 to 9 months. Hypothesis Early removal of the graft with appropriate infection management followed by early reimplantation can lead to good results. Study Design Uncontrolled retrospective review. Methods Records of all patients who developed postoperative infection after anterior cruciate ligament reconstruction were reviewed. Four patients had early graft removal and appropriate infection management including 6 weeks of intravenous antibiotics followed by anterior cruciate ligament graft reimplantation within 6 weeks of completion of antibiotic therapy. Results Follow-up at an average of 21 months (range, 14 to 31) showed that the patients treated with early reimplantation had full symmetric knee range of motion and no effusion. The average modified Lysholm score was 92.5. Radiographs demonstrated no joint-space narrowing or osteophyte formation. The 30-pound KT-1000 arthrometer side-to-side difference averaged 3 mm. Conclusion Graft removal after confirmed anterior cruciate ligament graft infection and intravenous antibiotic administration followed by early graft reimplantation can give excellent results.

The influence of tendon length and fit on the strength of a tendon-bone tunnel complex. A biomechanical and histologic study in the dog.

Using a dog model, we examined the influence of tendon length and fit within a bone tunnel on the pull-out strength of a tendon-bone tunnel complex at 6 weeks after fixation. Fourteen adult mongrel dogs (weight, 25 to 30 kg) underwent bilateral hindlimb surgery in which the extensor digitorum longus tendon was transplanted into an extraarticular metaphyseal bone tunnel. Our findings demonstrated that pull-out strength at 6 weeks was enhanced by increasing the length of tendon within the tunnel. The average load to failure with 1 cm of tendon within the tunnel was 153.7 78.6 N, compared with 265.5 93.3 N for the specimens with 2 cm of tendon in the tunnel. Tendon fit within the tunnel was also found to be important. The average load to failure when a tendon was placed in a 4.2-mm diameter tunnel was 301 61 N at 6 weeks. The average load to failure when the tendon was placed within a 6-mm diameter tunnel was 228 65 N. These differences were statistically different. Histologically, the interface between the tendon and bone appeared to be most mature when there was intimate bone-to-tendon contact. These data suggest that maximizing tendon length within a bone tunnel and minimizing tendon-tunnel diameter mismatch will maximize the strength of a tendon-bone tunnel complex at 6 weeks.

Effects of Platelet-Rich Fibrin Matrix on Repair Integrity of At-Risk Rotator Cuff Tears:

Background: Increased age, larger tear size, and more advanced fatty degeneration of the rotator cuff musculature have been correlated with poorer healing rates after rotator cuff repair. Platelets are an endogenous source of growth factors present during rotator cuff healing. Hypothesis: Augmentation of rotator cuff repairs with platelet-rich fibrin matrix (PRFM) may improve the biology of rotator cuff healing and thus improve functional outcome scores and retear rates after repair. Study Design: Cohort study; Level of evidence, 3. Methods: Rotator cuff tears at risk for retear were prospectively identified using an algorithm; points were assigned for age (50-59 years = 1; 60-69 years = 2; >70 years = 3), anterior-to-posterior tear size (2-2.9 cm = 0; 3-3.9 cm = 1; >4 cm = 2), and fatty atrophy (Goutallier score 0-2 = 0; Goutallier score 3-4 = 1). Three points were required for enrollment. Arthroscopic rotator cuff repair was performed with the addition of PRFM. Preoperative and 1-year postoperative magnetic resonance imaging (MRI) and functional outcome scores were obtained. Imaging and functional outcomes were compared with historical controls meeting the same enrollment criteria. Results: Sixteen and 21 patients were enrolled in the PRFM and control groups, respectively. Mean age (65 ± 7 and 65 ± 9 years; P = .89), tear size (3.8 ± 1.1 and 3.9 ± 1.1 cm; P = .79), and median Goutallier scores (2 and 3; P = .18) were similar between the PRFM and control groups, respectively. Retear rates (56.2% vs 38.1%) were statistically significantly higher (P = .024) in the PRFM group compared with controls. Functional outcome scores postoperatively were not significantly improved compared with controls. Complications included 2 infections in the PRFM group. Conclusion: The augmentation of at-risk rotator cuff tears with PRFM did not result in improved retear rates or functional outcome scores compared with controls.

Effect of Lateral Meniscal Allograft Sizing on Contact Mechanics of the Lateral Tibial Plateau An Experimental Study in Human Cadaveric Knee Joints

Background A mismatch of the original lateral meniscus and a lateral meniscus allograft by inaccurate preoperative radiographic sizing can have significant consequences on ultimate function. Hypothesis The size of a lateral meniscal allograft affects the contact mechanics of the femoral condyle on the tibial plateau. Study Design Controlled laboratory study. Methods Four right and 2 left knees were tested as intact joints, after meniscectomy, and after replantation with the original menisci and 16 right or 9 left human, fresh-frozen lateral meniscal allografts, respectively. The allografts were allocated into 7 groups according to their outer and inner anteroposterior and mediolateral diameters. Biomechanical testing was performed as compressive loadings with constrained motions in extension and 30° of flexion. Measurements were done with Fuji pressure-sensitive films for contact parameters of the direct femorotibial and meniscotibial contact. Results Oversized lateral meniscal allografts led to greater forces across the articular cartilage, whereas undersized allografts resulted in normal forces across the articular cartilage but greater forces across the meniscus. Two undersized transplants failed. Most of the contact parameters of allografts 10% smaller or larger than the original menisci were in the range of the intact knees. The knees after meniscectomy showed greater forces of the direct femorotibial contact areas than did the intact knees and the knees with the replanted original menisci. The contact mechanics of the knees with the replanted original menisci were close to normal. Conclusion The size of a lateral meniscal allograft has a significant effect on the contact mechanics of the tibial plateau. Clinical Relevance Preoperative radiographic sizing needs to be performed precisely to identify a suitable lateral meniscal allograft. A mismatch may be the reason for failure of the allograft or subsequent development of degenerative changes. A mismatch on graft selection of less than 10% of the size of the original meniscus may be acceptable.

Patellofemoral Contact Pressures and Lateral Patellar Translation After Medial Patellofemoral Ligament Reconstruction

Background Overtensioning of medial patellofemoral ligament reconstructions may lead to adverse surgical outcomes. Hypothesis Increasing tension on a medial patellofemoral ligament graft will increase patellofemoral contact forces and decrease lateral patellar translation. Study Design Controlled laboratory study. Methods Patellofemoral contact pressures were measured in 8 fresh-frozen cadaveric knees before and after transection of the medial patellofemoral ligament and after a standardized reconstruction surgery. Contact pressures were measured at 3 knee angles (30°, 60°, and 90°) and under 3 levels of tension applied to the graft (2, 10, and 40 N). For each condition, patellar translation was measured at 30° of knee flexion as a 22-N lateral force was applied. Results Graft tension of 2 N restored normal translation, but 10 N and 40 N significantly restricted motion (5.2 mm and 1.9 mm, respectively). Compared with the intact knee, medial patellofemoral contact pressures significantly increased (P < .05) when 40 N of tension was applied to the reconstruction. Medial contact pressures were restored to normal with 2 N of graft tension. Lateral patellar translation was significantly greater (P < .05) after the medial patellofemoral ligament was cut (16.3 mm) compared with intact (7.7 mm). Conclusion Low (2-N) tension applied to a medial patellofemoral ligament reconstruction stabilized the patella and did not increase medial patellofemoral contact pressures. Higher loads (10 N and 40 N) progressively restricted lateral patellar translation and inappropriately redistributed patellofemoral contact pressures. Clinical Relevance Overtensioning can be avoided by applying low loads to medial patellofemoral ligament reconstructions, which reestablished normal translation and patellofemoral contact pressures.