Jeffrey A. Macalena

Correlation of Valgus Stress Radiographs With Medial Knee Ligament Injuries An In Vitro Biomechanical Study

Background The amount of medial compartment opening for medial knee injuries determined by valgus stress radiography has not been well documented. The purpose of this study was to develop clinical guidelines for diagnosing medial knee injuries using valgus stress radiography. Hypothesis Measurements of medial compartment gapping can accurately differentiate between normal and injured medial structure knees on valgus stress radiographs. Study Design Controlled laboratory study. Methods Valgus stress radiographs were obtained on 18 adult lower extremities using 10-N·m and clinician-applied valgus loads at 0° and 20° of flexion to intact knees and after sequential sectioning of the superficial medial collateral ligament proximally and distally, the meniscofemoral and meniscotibial portions of the deep medial collateral ligament, the posterior oblique ligament, and the cruciate ligaments. Three independent observers of different experience levels measured all of the radiographs during 2 separate occasions to determine intraobserver repeatability and interobserver reproducibility. Results Compared with the intact knee, significant medial joint gapping increases of 1.7 mm and 3.2 mm were produced at 0° and 20° of flexion, respectively, by a clinician-applied load on an isolated grade III superficial medial collateral ligament simulated injury. A complete medial knee injury yielded gapping increases of 6.5 mm and 9.8 mm at 0° and 20°, respectively, for a clinician-applied load. Intraobserver repeatability and interobserver reproducibility intraclass correlation coefficients were .99 and .98, respectively. Conclusion Valgus stress radiographs accurately and reliably measure medial compartment gapping but cannot definitively differentiate between meniscofemoral- and meniscotibial-based injuries. A grade III medial collateral ligament injury should be suspected with greater than 3.2 mm of medial compartment gapping compared to the contralateral knee at 20° of flexion, and this injury will also result in gapping in full extension. Clinical Significance Valgus stress radiographs provide objective and reproducible measurements of medial compartment gapping, which should prove useful for definitive diagnosis, management, and postoperative follow-up of patients with medial knee injuries.

A Simple Evaluation of Anterior Cruciate Ligament Femoral Tunnel Position: The Inclination Angle and Femoral Tunnel Angle

Background: Postoperative determination of tunnel position after anterior cruciate ligament (ACL) reconstruction can be challenging. Hypothesis: The femoral tunnel angle and inclination angle are reliable methods for evaluating tunnel position after ACL reconstruction while aiding in determining whether an ACL reconstruction falls outside an anatomic range as defined on 3-dimensional (3D) computed tomography (CT). Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: Fifty patients were included who received single-bundle ACL reconstructions with postoperative flexion weightbearing radiographs, magnetic resonance imaging (MRI), and CT scans. Femoral tunnel angles were determined from posterior-to-anterior postoperative radiographs, and inclination angles were determined from sagittal MRI. The ACL reconstructions were grouped by surgical technique, transtibial (TT) or tibial tunnel independent (TTI), and as either falling inside or outside an anatomic range on 3D CT. Results: Patients with tunnel positions within an anatomic range, as previously defined, had a larger femoral tunnel angle (39.3° ± 4.2°) and smaller inclination angle (49.5° ± 2.7°) than patients who fell outside an anatomic range (17.2° ± 12.5° and 62.3° ± 7.8°, respectively) (P < .001). Patients in the TTI group had a larger femoral tunnel angle (37.6° ± 9.30°) and smaller inclination angle (51.8° ± 6.5°) than those in the TT group (14.2° ± 9.3° and 63.5° ± 7.2°, respectively) (P < .001). Posterior-to-anterior femoral tunnel position was negatively correlated with femoral tunnel angle (P < .001, r = .78) and positively correlated with inclination angle (P < .001, r = .74). Based on a receiver operating characteristic (ROC) curve, a femoral tunnel angle of 32.7° (100% sensitivity and 85% specificity) and inclination angle of 55° (100% sensitivity and 87.5% specificity) were determined to distinguish ACL reconstructions that fell either within or outside an anatomic range on 3D CT. Conclusion: Femoral tunnel angle and inclination angle can be reliably determined from both posterior-to-anterior radiographs and sagittal MRI and provide a useful metric for characterizing femoral tunnel position.

Anatomic and Radiographic Comparison of Arthroscopic Suprapectoral and Open Subpectoral Biceps Tenodesis Sites

Background: Arthroscopic suprapectoral and open subpectoral surgical techniques are both commonly utilized approaches for proximal biceps tenodesis of the long head of the biceps brachii. A central limitation to the widespread use of an arthroscopic approach for biceps tenodesis is that the tendon may be tenodesed too proximally in the bicipital groove, leading to persistent pain and tendinopathy. Purpose/Hypothesis: The purpose of this study was to determine the in vivo tenodesis location using arthroscopic suprapectoral and open subpectoral techniques for proximal biceps tenodesis in relation to clinically pertinent anatomic and radiographic landmarks. The null hypothesis was that arthroscopic suprapectoral biceps tenodesis would not be significantly different in terms of the location from open subpectoral biceps tenodesis. Study Design: Controlled laboratory study. Methods: A total of 20 matched pairs of cadaveric shoulder specimens were randomized such that within each pair, 1 shoulder underwent a standard open subpectoral biceps tenodesis and the other underwent an arthroscopic suprapectoral tenodesis. Limited dissection and exposure of the surgical tunnel site and reference landmarks were subsequently performed, and anteroposterior and lateral radiographs were obtained. Direct measurements were performed anatomically using a digital caliper and radiographically using picture archiving and communication system (PACS) software from the proximal lip of the humeral tunnel to regional landmarks. Results: Both techniques were able to place the humeral tunnel distal to the bicipital groove in all specimens. On average, the open subpectoral approach placed the tunnel 2.2 cm distal to the arthroscopic suprapectoral approach. Conclusion: The arthroscopic suprapectoral biceps tenodesis technique used in this study consistently placed the tenodesis tunnel distal to the bicipital groove, which may allay concerns about the bicipital groove as a pain source after this procedure. Clinical Relevance: This anatomic study provides new information on tunnel placement in 2 biceps tenodesis techniques. In addition, it provides clinically relevant anatomic and radiographic guidelines using clinically pertinent landmarks. This information may be useful in preoperative planning, intraoperative technique, and postoperative assessment of both open subpectoral and arthroscopic suprapectoral biceps tenodesis.

Biomechanical comparison of patellar fixation techniques in medial patellofemoral ligament reconstruction.

Background: Multiple techniques for reconstruction of the medial patellofemoral ligament (MPFL) have been described; however, little is known about the biomechanical properties of these techniques. Fixation of the graft to the patella has not been studied in a human cadaveric model. Hypothesis/Purpose: The purpose of this study was to compare the ultimate failure load and stiffness of 2 different MPFL patellar fixation techniques: suture anchor fixation and interference screw fixation. The null hypothesis was that the suture anchor group would show no difference in the ultimate failure load and stiffness compared with the interference screw group. Study Design: Controlled laboratory study. Methods: Reconstruction of the MPFL with semitendinosus autografts was performed in 8 pairs of fresh-frozen cadaveric knees (16 knees total; mean age, 55.8 ± 7.7 years). The specimens were randomly assigned to 2 groups of 8 specimens each based on the method used to fix the graft to the medial patella: suture anchor or interference screw fixation. Each reconstruction technique was performed on 1 knee from the same cadaveric specimen. Suture anchor reconstruction was completed with 2 parallel 3.0-mm biocomposite suture anchors. Interference screw fixation was accomplished with two 4.75-mm biocomposite interference screws docked in parallel tunnels. The reconstructions were cyclically loaded for 10 cycles to 30 N and then tested to failure at a constant displacement rate of 6 mm/s with a line of pull parallel to the anchors or interference screws. Ultimate failure load (N), stiffness (N/mm), and mode of failure were recorded for each specimen. Results: The suture anchor group had a significantly lower mean failure load (201.54 ± 63.14 N) than the interference screw group (299.25 ± 99.87 N) (P = .007). The suture anchor group also had significantly lower mean stiffness (20.60 ± 6.78 N/mm) compared with the interference screw group (34.66 ± 10.74 N/mm) (P = .007). The most common mode of failure in the suture anchor group was failure at the graft-suture interface. In the interference screw group, the most common mode of failure was the tendon graft pulling out of the tunnel. Conclusion: Interference screw fixation to the medial patella was found to be significantly stronger than suture anchor fixation when comparing the ultimate failure load and stiffness. Clinical Relevance: This study compares the biomechanical properties of 2 commonly used methods for patellar graft fixation in MPFL reconstruction surgery. It supports the use of interference screw fixation based on the ultimate load and stiffness, although suture anchor fixation may be sufficient when compared with the native MPFL based on previously published data.

Magnetic Resonance Imaging of Osteochondritis Dissecans: Validation Study for the ICRS Classification System.

RATIONALE AND OBJECTIVES In this retrospective case series, we utilize arthroscopy as the gold standard to determine if magnetic resonance imaging (MRI) of the knee can predict osteochondritis dissecans (OCD) lesion stability, the most important information to guide patient treatment decisions. It is hypothesized that the classification system of the International Cartilage Repair Society (ICRS) will allow for improved assessment of lesion grade and stability in OCD. MATERIALS AND METHODS Routine MRI studies of 46 consecutive patients with arthroscopically proven OCD lesions (mean age: 23.7 years; 26 male, 16 female) were assessed by three radiologists who were blinded to arthroscopic results. Arthroscopic images were evaluated by two orthopedic surgeons in consensus. The OCD criteria of the ICRS were applied to arthroscopy and imaging interpretations. Inter-rater correlation statistics and accuracy of magnetic resonance (MR) grading with respect to arthroscopy were determined. RESULTS Only 56% of the available MR reports assigned a label of stable or unstable to the lesion description. Of these, 58% of the lesions were deemed unstable and 42% were stable. Accuracy was 53% when reports addressed stability. Utilizing the ICRS classification system, for all three readers combined, the respective sensitivity, specificity, and accuracy of MR imaging to determine lesion stability were 70%, 81%, and 76%. When compared to the original MRI report, the overall accuracy increased from 53% to 76% when readers were given the specific criteria of the OCD ICRS classification. However, inter-reader variability remained high, with Krippendorfs alpha ranging from 0.48 to 0.57. CONCLUSIONS In this paper, we utilize arthroscopy as the gold standard to determine if MRI can predict OCD lesion stability, the most important information to guide patient treatment decisions. To our surprise, the analysis of the existing radiology reports that addressed stability revealed an overall accuracy in defining OCD lesion stability of about 53%. The classification system of the ICRS, created by an international multidisciplinary, multi-expert consortium, did markedly improve the accuracy, but consistency among different readers was lacking. This retrospective study on OCD reporting and classification highlights the inadequacy of existing classification schemes, and emphasizes the critical need for improved diagnostic MRI protocols in musculoskeletal radiology in order to propel it toward evidence-based medicine.

Anterior cruciate ligament assessment using arthrometry and stress imaging

Arthrometry and stress imaging are useful clinical tools for the objective assessment of anterior cruciate ligament (ACL) integrity. They are most frequently used for the diagnosis of a complete ACL tear when other workup is equivocal, in conjunction with history and clinical exam findings. Other applications include the diagnosis of partial ACL tears, injury prognosis, and post-operative monitoring. However, further studies are needed to validate these uses. Many different devices and techniques exist for objective examination, which have been compared in recent literature. Reliability and validity measures of these methods vary, and often depend upon examiner familiarity and skill. The KT series of devices is the current gold standard for arthrometry, although the newer robotic GNRB device shows promising early results. Newer methods of data interpretation have been developed for stress imaging, and portable technology may impact this field further.

Fibular Head as a Landmark for Identification of the Common Peroneal Nerve: A Cadaveric Study

PURPOSE The purpose of this study was to identify the relationship between the common peroneal nerve (CPN) and the fibular head. METHODS Sixteen cadaveric dissections were performed. The distance from the fibular head to the center of the CPN as it exits beneath the biceps femoris (BF) was measured in 0°, 30°, 60°, and 90° of flexion and was averaged on the first 8 specimens. Based on those measurements, a needle was placed on the second 8 dissections before the fascial incision was made to assess reliability. All measurements were repeated after needle removal, distances were recorded, and 95% confidence interval (CI) and correlation coefficients were calculated. RESULTS The distance from the posterior border of the fibular head to where the CPN nerve center emerges from the BF was 62.3 mm (95% confidence interval [CI], 58.2 to 66.4), 56.3 mm (95% CI, 51.9 to 60.8), 46.8 mm (95% CI, 43.6 to 50.0), and 45.3 mm (95% CI, 43.2 to 47.3) in 0°, 30°, 60°, and 90° of knee flexion, respectively. The correlation coefficient between knee flexion and measured distance was nearly linear: r = -0.97. The correlation coefficients were 0.62, 0.32, and 0.01 for height, weight, and body mass index (BMI), respectively. The CPN crossed the posterior border of the fibula 21.9 mm (95% CI, 20.2 to 23.7) from the fibular styloid at 90° of flexion. CONCLUSIONS With the knee in 90° of flexion, the CPN center crosses the long head of the BF (LHBF) tendon 45.3 mm from the posterior border of the fibula, where the direct arm of the BF inserts, and the posterior border of the fibula 21.9 mm from the tip of the fibular styloid. There is a near linear correlation between knee flexion and the distance to the CPN as it exits the BF. No correlation exists between the distance to the CPN and weight or BMI, whereas a moderate correlation with height exists. CLINICAL RELEVANCE These relationships allow for efficient and safe identification of the CPN proximal to the zone of injury when operating around the posterior lateral corner (PLC) of the knee.

Insights into the Epiphyseal Cartilage Origin and Subsequent Osseous Manifestation of Juvenile Osteochondritis Dissecans with a Modified Clinical MR Imaging Protocol: A Pilot Study

Purpose To retrospectively determine if a modified clinical magnetic resonance (MR) imaging protocol provides information on the origin of juvenile osteochondritis dissecans (JOCD) lesions and allows for staging on the basis of the proposed natural history of JOCD to better guide clinical management of the disease. Materials and Methods This institutional review board-approved, HIPAA-compliant, retrospective study was performed in 13 consecutive patients (mean age, 14.9 years; age range, 10-22 years; nine male and four female patients) and one additional comparative patient (a 44-year-old man), in which 19 knees with 20 JOCD lesions were imaged. Seventeen lesions occurred in the medial femoral condyle, two occurred in the lateral femoral condyle, and one occurred in the medial trochlea. The clinical 3-T MR imaging protocol was supplemented with a routinely available multiecho gradient-recalled-echo sequence with the shortest attainable echo time of approximately 4 msec (T2* mapping). Results At the earliest manifestation, the lesion was entirely cartilaginous (n = 1). Subsequently, primary cartilaginous lesions within the epiphyseal cartilage developed a rim calcification that originated from normal subjacent bone, which defined a clear cleft between the lesion progeny and the parent bone (n = 9). Secondarily, progeny lesions became ossified (n = 7) while at the same time forming varying degrees of osseous bridging and/or clefting with the parent bone. Two healed lesions with a linear bony scar and one detached lesion were identified. Conclusion The modified MR imaging protocol allowed for identification of the epiphyseal cartilage origin and subsequent stages of ossification in JOCD. The approach allows further elucidation of the natural history of the disease and may better guide clinical management.

Bacterial Contamination of a Marking Pen in Anterior Cruciate Ligament Reconstruction

Background: A sterile surgical marking pen is commonly used during anterior cruciate ligament reconstruction (ACLR) to outline the proposed skin incision and then to mark the graft during preparation. Once in contact with the skin, the pen is a potential source of bacterial transmission and subsequent infections after ACLR. Purpose/Hypothesis: The purpose of this study was to assess whether the skin marking pen is a fomite for contamination during arthroscopic ACLR. We hypothesized that there would be a difference in the rate of culture-positive pens between control pens and the study pens used to delineate the proposed skin incision. Study Design: Controlled laboratory study. Methods: Twenty surgical marking pens were collected prospectively from patients undergoing ACLR over a 12-month period. All patients underwent standard preoperative sterile preparation and draping procedures. Proposed incisions were marked with a new sterile pen, and the pen tip was immediately sent for a 5-day inoculation in broth and agar. Negative controls (unopened new pen) and positive controls (used to mark the skin incisions preoperatively) were also cultured. Additionally, blank culture dishes were observed during the growth process. All pens were removed from the surgical field before incision, and new marking pens were used when needed during the procedure. Results: Three of the 20 study pens (15%) demonstrated positive growth. All 3 pens grew species of Staphylococcus. None of the negative controls demonstrated growth, 6 of the 12 positive controls showed growth, and none of the blank dishes exhibited growth. Conclusion: This study found a 15% rate of surgical marking pen contamination by Staphylococcus during ACLR. It is recommended that the skin marking pen not be used for any further steps of the surgical case and be discarded once used. Clinical Relevance: Infections after ACLR are rare but may result in significant morbidity, and all measures to reduce them should be pursued. Surgeons performing ACLR should dispose of the surgical marking pen after skin marking and before intraoperative use such as graft markup.

MRI and Arthroscopy Correlation in the Patellofemoral Joint

The patellofemoral joint is an articulation between the patella and the femoral trochlea, which serves to increase the lever arm of the extensor mechanism. The stability of the patella within the trochlear groove is supported statically by the bony confines of the groove itself, as well as the medial patellofemoral ligament, and dynamically by the vastus musculature. Pathologic changes seen on magnetic resonance imaging (MRI) are frequently well correlated with findings found by arthroscopy at the time of surgery. Degenerative changes to the articular cartilage, osteochondral lesions and loose bodies, tears in the retinaculum, and the medial patellofemoral ligament can be seen in MRI and are well correlated with arthroscopy. In addition, other findings that may predispose an individual to injury or degenerative changes over time, such as patella alta and trochlear dysplasia, can also be assessed by MRI and observed arthroscopically.