Lateral Patellar Inclination Angle Measured via a Two-Image Technique on Axial Magnetic Resonance Imaging.

Lateral patellar inclination (LPI) measures patellar tilt and is historically described on axial X-ray or a single magnetic resonance image (MRI). Given the variability in patellar height, LPI may be better represented by performing this measurement on two separate axial MRI images. We hypothesized that a two-image LPI measurement would be different from the current single-image LPI and have similar, if not superior reliability. Sixty-five patients treated for patellar instability (PI) between 2014 and 2017 were identified. Single image and two-image LPI were measured on axial MRI images. All measurements were performed by two independent observers. Reliability analysis was based on three observers' measurements of 30 randomly selected patients. Both the one image and two image LPI showed good inter-rater reliability (intraclass correlation coefficient [ICC] = 0.71 and 0.89, respectively), although the two image LPI had less variability. Both single image and two image LPI had near perfect intra-rater reliability (ICC = 0.98 and 0.98, respectively). Average single image LPI (14.6 ± 9.9 degrees) was 6.1 ± 3.4 degrees less than the average two image LPI (19.6 ± 9.4 degrees) (p = 0.037). Referencing a previously described 13.5 degrees maximum threshold, 54% of the patients had excessive patellar tilt based on single image LPI, while 73% had pathologic patellar tilt based on two image LPI. Two image LPI has similar reliability with less inter-rater variability compared with the historical single image LPI measurement. Significantly greater patellar tilt was identified with two image LPI that was found with single image LPI. A larger percentage of patients were classified as having pathologic patellar tilt based on two image LPI than single image LPI. The two image LPI provides more consistent and representative measurements of patellar tilt. Previously described threshold values for patellar tilt should be re-examined using this new measurement technique to appropriately risk stratify patients with PI and patellofemoral pain.

Lateral Trochlear Inclination Angle: Measurement via a 2-Image Technique to Reliably Characterize and Quantify Trochlear Dysplasia.

BACKGROUND: Trochlear dysplasia (TD) is a risk factor for patellar instability (PI). The Dejour classification categorizes TD but has suboptimal reliability. Lateral trochlear inclination (LTI) is a quantitative measurement of trochlear dysplasia on a single axial magnetic resonance imaging (MRI) scan. HYPOTHESIS: A modified LTI measurement technique using 2 different axial MRI scans that reference the most proximal aspect of the trochlear cartilage on 1 image and the fully formed posterior condyles on the second image would be as reliable as and significantly different from the single-image measurement technique for LTI. Further, the 2-image LTI would adequately represent overall proximal trochlear morphologic characteristics. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Patients aged 9 to 18 years treated for PI between 2014 and 2017 were identified. The Dejour classification was radiographically determined. Single-image LTI was measured on a single axial MRI scan at the most proximal aspect of visible trochlear cartilage. A 2-image LTI was measured from 2 separate MRI scans: 1 at the most proximal aspect of trochlear cartilage and the second at the fully formed posterior condyles. This 2-image LTI was repeated at 3 subsequent levels (the first measurement is referred to as LTI-1; repeated measurements are LTI-2, LTI-3, and LTI-4, moving distally). In total, 65 patients met the inclusion criteria, and 30 were randomly selected for reliability analysis. RESULTS: Inter- and intrarater reliability trended toward more variability for single-image LTI (intraclass correlation coefficient [ICC], 0.86 and 0.88, respectively) than for 2-image LTI (ICC, 0.97 and 0.96, respectively). The Dejour classification had lower intra- and interrater reliability (ICC, 0.31 and 0.73, respectively). Average single-image LTI (9.2° ± 12.6°) was greater than average 2-image LTI-1 (4.2° SD ± 11.9°) (P = .0125). Single-image LTI classified 60% of patients with PI as having TD, whereas the 2-image LTI classified 71% as having TD. The 2-image LTI was able to capture 91% of overall proximal trochlear morphologic characteristics. CONCLUSION: LTI has higher reliability when performed using a 2-image measurement technique compared with single-image LTI and Dejour classification. The strong correlation between 2-image LTI and average LTI shows that 91% of TD is represented on the most proximal axial image. Because the single-image measurement appears to underestimate dysplasia, previously described thresholds should be reexamined using this 2-image technique to appropriately characterize TD.

Effect of Trochlear Dysplasia on Commonly Used Radiographic Parameters to Assess Patellar Instability.

BACKGROUND: Trochlear dysplasia (TD) is an important anatomic risk factor for patellar instability (PI). Several imaging-based risk factors for PI have been established, but it is unclear what effect TD has on these measurements, and the Dejour method of categorizing TD has been shown to be unreliable. The lateral trochlear inclination (LTI) is a quantifiable measurement of proximal trochlear morphology. Recently, a modified technique for measuring LTI referencing the posterior condylar angle has demonstrated near-perfect reliability and may serve as a new standard for quantifying TD. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate how TD, expressed in terms of LTI, affects historically used measures of PI, including the sulcus angle (SA), tibial tuberosity to trochlear groove (TT-TG) distance, lateral patellar inclination (LPI), and Caton-Deschamps (CD) ratio. We hypothesized that lower LTI (ie, more dysplastic trochlea) will correlate with higher SA and TT-TG distances, increased patellar tilt, and more patella alta. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Patients aged 9 to 18 years treated for PI between January 2014 and August 2017 were queried. On magnetic resonance imaging (MRI), LTI, SA, LPI, and the TT-TG measured at the most proximal (pTT-TG) and distal (dTT-TG) aspects of the fully formed trochlear groove were measured on axial images. CD ratio was measured using sagittal MRI as well as lateral radiographs. All measurements were performed by 2 independent observers. Patients were included if there was a diagnosis of PI that was confirmed with a chart review and if there were appropriate imaging studies to analyze. RESULTS: A total of 65 patients met inclusion criteria for this study. Average pTT-TG distance (15.7 ± 4.5 mm) was not significantly different from dTT-TG distance (15.7 ± 4.2 mm) (P = .94). LTI had a weak but significant inverse correlation with pTT-TG (r = -0.40; ß = -0.15 mm; P < .001) and SA (r = -0.43; ß = -0.478°; P < .001). There was a moderate and significant inverse correlation of LTI with dTT-TG (r = -0.593; ß = -0.21 mm; P < .001) and with LPI (r = -0.69; ß = -0.54°; P < .001). There was a weak but significant correlation between LTI and the MRI-based CD ratio (r = 0.279; ß = 0.149; P = .005). Radiograph-based CD ratio did not show a significant correlation with LTI (r = -0.189; P = .135). CONCLUSION: Smaller (ie, more dysplastic) LTI values correlated significantly with larger TT-TG, SA, LPI, and MRI-based CD ratio measurements. The relationship between SA and LTI is intuitive, but the relationship between LTI and the other analyzed variables suggests that they are dependent variables to TD and may not be consistent independent risk factors for PI. Together, these suggest that TD alters the radiographic interpretation of TT-TG and patellar tilt. The correlation between TD and patellar height is unclear and warrants further investigation.

Medial Quadriceps Tendon Femoral Ligament Reconstruction Technique and Surgical Anatomy.

Medial patellofemoral ligament reconstruction risks patellar fracture with the osseous violation necessary for patellar attachment. Anatomic studies identify an entire medial patellofemoral complex of structures responsible for medial restraint to patellar lateral instability. One specific component of this complex is the medial quadriceps tendon femoral ligament (MQTFL). This note presents the technique, pearls and pitfalls, and critical surgical anatomy necessary for successful MQTFL reconstruction-a treatment strategy for patellar instability with no increased risk for patellar fracture. An autograft hamstring tendon or allograft tendon is fixed to the anatomically identified femoral origin and passed deep to the vastus medialis obliquus to then weave around the distal medial quadriceps tendon. This simulates the native anatomic interdigitation of the MQTFL with the quadriceps tendon and provides a stable restraint to prevent lateral patellar subluxation or dislocation.

Treatment of ACL Tears in the Skeletally Immature Patient.

The understanding and treatment of anterior cruciate ligament tears in skeletally immature patients continues to evolve. While conservative management was a mainstay of treatment, poor outcomes have led to several surgical techniques aimed at stabilizing the knee, optimizing outcome, and minimizing the chance of growth disturbance. Current techniques have, in large part, accomplished these goals but challenges remain. Looking to the future, different graft options, primary repair techniques, and rigorous prospective studies will help improve outcomes for this challenging patient population.

Arthroscopic Viewing Position Affects Anterior Cruciate Ligament Reconstruction Femoral Tunnel Length Measurements.

PURPOSE: To purpose of this study was to compare arthroscopic anterior cruciate ligament (ACL) reconstruction femoral tunnel length measurements from the anterolateral portal between the standard notch view using a 30° arthroscope versus a "top-down" view utilizing a 70° arthroscope to visual the far side of the femoral tunnel aperture. METHODS: Arthroscopic femoral tunnel length measurements using calibrated reamers from the standard notch versus the "top-down" view were obtained and reviewed in 54 skeletally mature patients undergoing ACL reconstruction with no prior bony knee surgery. Patient age, height, weight, sex, and surgery laterality were also recorded. Measurements of femoral tunnel length were repeated using both views for inter-observer and intra-observer correlation. RESULTS: Inter-observer and intra-observer intra-class correlation coefficients for the standard notch view and "top-down" views were excellent, with higher reliability values appreciated using the "top down" view. Mean overall femoral tunnel length measurements obtained using the standard notch view were significantly longer than measurements from the "top-down" view (p < 0.001). CONCLUSIONS: The standard notch view provides significantly longer femoral tunnel length measurements in comparison to the "top-down" view.

Cost Analysis of Hemiarthroplasty Versus Reverse Shoulder Arthroplasty for Fractures.

Complex proximal humerus fractures in older patients can be treated with hemiarthroplasty (HA) or reverse shoulder arthroplasty (RSA), with both providing good pain relief and function. This study compared the costs, complications, and outcomes of HA vs RSA after proximal humerus fracture in older patients. Patients 65 years or older who were admitted between January 2007 and August 2011 with a 3- or 4-part proximal humerus fracture and treated with HA or RSA were identified. Surgeries were performed at the same institution by 1 of 3 surgeons trained in trauma or shoulder surgery. Operating room costs, implant costs, total costs to the patient and hospital, and range of motion were compared. In the study group, 8 patients (7 women and 1 man; mean age, 77 years) received HA and 16 patients (13 women and 3 men; mean age, 77 years) received RSA. Hemiarthroplasty implant cost and operating room cost were $9140 and $8900 less than those of RSA, respectively (P<.001). The total cost to the patient was $33,480 for HA vs $57,000 for RSA (P<.001) with no difference in admission length, transfusion requirements, or final range of motion. In patients with complex proximal humerus fractures, RSA restored function similar to HA and resulted in better pain and outcome scores. However, RSA had a significantly higher cost to both the patient and the hospital compared with HA. Further investigation of postsurgical rehabilitation costs, skilled nursing needs, or revision surgery will elucidate whether there is long-term functional or financial benefits to RSA over HA. [Orthopedics. 2016; 39(4):230-234.].