Hip arthroscopy for lateral cam morphology: how important are the vessels?

The purpose of this narrative review is to identify the anatomy and relevant blood supply to the femoral head as it pertains to hip arthroscopy and lateral cam morphology. The primary blood supply to the femoral head is the lateral ascending superior retinacular vessels, which are terminal branches of the medial femoral circumflex artery. These vessels penetrate the femoral head at the posterolateral head-neck junction. Surgeons performing posterolateral femoral osteoplasty must respect this vasculature to avoid iatrogenic avascular necrosis (AVN). Avoidance of excessive traction, avoidance of distal posterolateral capsulotomy and avoidance of disruption of the superior retinacular vessels should keep the risk for AVN low. Hip extension, internal rotation and distraction are useful in hip arthroscopy to better visualize lateral/posterolateral cam morphology to facilitate an accurate comprehensive cam correction and avoid vascular disruption.

Validation of Digital Visual Analog Scale Pain Scoring With a Traditional Paper-based Visual Analog Scale in Adults.

BACKGROUND: The visual analog scale (VAS) is a validated, subjective measure for acute and chronic pain. Scores are recorded by making a handwritten mark on a 10-cm line that represents a continuum between "no pain" and "worst pain." METHODS: One hundred consecutive patients aged ≥18 years who presented with a chief complaint of pain were asked to record pain scores via a paper VAS and digitally via both the laptop computer and mobile phone. Ninety-eight subjects, 51 men (age, 44 ± 16 years) and 47 women (age, 46 ± 15 years), were included. A mixed-model analysis of covariance with the Bonferroni post hoc test was used to detect differences between the paper and digital VAS scores. A Bland-Altman analysis was used to test for instrument agreement between the platforms. The minimal clinically important difference was set at 1.4 cm (14% of total scale length) for detecting clinical relevance between the three VAS platforms. A paired one-tailed Student t-test was used to determine whether differences between the digital and paper measurement platforms exceeded 14% (P < 0.05). RESULTS: A significant difference in scores was found between the mobile phone-based (32.9% ± 0.4%) and both the laptop computer- and paper-based platforms (31.0% ± 0.4%, P < 0.01 for both). These differences were not clinically relevant (minimal clinically important difference <1.4 cm). No statistically significant difference was observed between the paper and laptop computer platforms. Measurement agreement was found between the paper- and laptop computer-based platforms (mean difference, 0.0% ± 0.5%; no proportional bias detected) but not between the paper- and mobile phone-based platforms (mean difference, 1.9% ± 0.5%; proportional bias detected). CONCLUSION: No clinically relevant difference exists between the traditional paper-based VAS assessment and VAS scores obtained from laptop computer- and mobile phone-based platforms.

MRI prevalence and characteristics of supraacetabular fossae in patients with hip pain.

BACKGROUND: Supraacetabular fossae (SAF) are normal anatomic variants found at the 12 o'clock position of the acetabulum and can be mistaken for osteochondral defects. PURPOSE: Determine SAF prevalence on MRI of patients with hip pain. Characterise SAF by type, size, and location. Determine sensitivity of radiology reports and sensitivity of radiographs in SAF detection. METHODS: MRIs performed over 1 year in patients with hip/groin pain were analysed for SAF. Measurements of SAF in the coronal and sagittal planes and location using clockface notation were recorded. Radiology reports were reviewed to determine if SAF were identified and radiographs were assessed for presence of SAF. Mean characteristics of type 1 and 2 SAF were compared using Student's t-test. RESULTS: 214 hips (mean age 35.9 ± 14.2 years; 66.8% female) were analysed. Twenty-seven hips (12.6%) had SAF. There were five type 1 SAF (mean age 16.8 ± 2.2 years) and 23 type 2 SAF (mean age 33.0 ± 16.3 years). Mean dimensions of type 1 and 2 SAF (coronal width × sagittal width × depth, in millimetres) were 7.1 × 6.5 × 3.4 and 6.1 × 5.9 × 2.8, respectively. Mean clockwise location in the coronal and sagittal planes (in minutes) was 1236 and 1212 for type 1 SAF and 1213 and 1207 for type 2 SAF. Radiology reports identified 7.1% of SAF identified on MRI. Plain radiographs demonstrated 67.9% of SAF identified on MRI. CONCLUSION: This study found a 12.6% prevalence of SAF in hips. Radiology reports had a 7.1% sensitivity in correctly identifying SAF on MRI. IRB: Pro00016584.

Current evidence advocates use of a new pathologic tibial tubercle-posterior cruciate ligament distance threshold in patients with patellar instability.

PURPOSE: To determine (1) whether a correlation exists between tibial tubercle-posterior cruciate ligament (TT-PCL) and tibial tubercle-trochlear groove (TT-TG) distances in patellar instability patients; (2) reliability when measuring TT-PCL distance; (3) whether TT-PCL distances measured on MRI are equivalent to those on CT; and (4) whether a correlation exists between TT-PCL distance and number of instability events or recurrence of instability following stabilization surgery. METHODS: A systematic review was performed using PRISMA guidelines. Clinical studies investigating the relationships of TT-PCL with TT-TG on CT and/or MRI in patellar instability patients were sought. English language studies with Levels of evidence I-IV were eligible for inclusion. RESULTS: Four studies (285 subjects [300 knees] with patellar instability [74.2% female; mean age 26.1 ± 8.2 years]; 114 controls [144 knees; 77% female; mean age 23.1 years]) were included. Mean TT-PCL of instability and control groups was 21.1 ± 4.1 and 18.8 ± 4.0 mm (p < 0.0001), respectively. Two studies reported significant positive (strong and moderate) correlations between TT-PCL and TT-TG MRI measurements in instability patients. All four investigations reported excellent interobserver and intraobserver reliability in MRI measurement of TT-PCL distance. No study compared TT-PCL distances on MRI and CT. No study assessed correlation between TT-PCL distance and number of instability events or recurrence of instability after surgery. CONCLUSION: A moderate-to-strong positive correlation exists between TT-PCL and TT-TG measurements taken from MRIs of patellar instability patients. There is excellent interobserver and intraobserver reliability when taking TT-PCL measurements using MRI. This review advocates use of a new pathologic TT-PCL threshold of 21 mm. LEVEL OF EVIDENCE: Level III, systematic review of Level II-III studies.

Is There an Association Between Noncontact Anterior Cruciate Ligament Injuries and Decreased Hip Internal Rotation or Radiographic Femoroacetabular Impingement? A Systematic Review.

PURPOSE: To perform a systematic review to determine if there is (1) an association between decreased hip internal rotation and anterior cruciate ligament (ACL) tear rates; (2) an association between radiographic femoroacetabular impingement (FAI) and ACL tear rates; and (3) biomechanical evidence demonstrating increased strain in the ACL of patients with decreased hip internal rotation. METHODS: A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies investigating relationships between hip motion, hip radiographs, and ACL tear were sought. Studies with Levels of evidence I-IV were eligible for inclusion. Study methodology/evidence were evaluated using Methodological Index for Non-Randomized Studies (MINORS), Strengthening the Reporting of Observational Studies in Epidemiology (STROBE), and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. RESULTS: Eleven studies were analyzed (2 cadaveric in vitro models, 8 clinical studies measuring hip internal rotation (2 concurrently assessing radiographic FAI), and 1 clinical study assessing radiographic FAI alone). Mean MINORS, STROBE, and GRADE for the studies was 82.4%, 20.9 out of 22, and "low," respectively. A total of 959 subjects (84.8% male; mean age 23.6 ± 3.8 years) were analyzed. Overall, 378 subjects sustained 427 ACL tears (399 primary ACL ruptures, 28 reruptures). Six of 8 clinical studies identified a significant association between limited rotation (internal rotation [IR; loss greater than 10°-20°], external rotation [ER], or combined IR + ER [loss greater than 20°]) and ACL tears. Two studies found an association between ACL ruptures and radiographic cam/pincer impingement. Two cadaveric models found a significant association between ACL strain and limited hip internal rotation. CONCLUSIONS: This systematic review identified a significant association between ACL tear and both limited hip rotation and radiographic FAI. LEVEL OF EVIDENCE: Level IV, systematic review of Levels II-IV studies.

CT density analysis of the medial cuneiform.

BACKGROUND: A cannulated lag screw inserted through the medial cuneiform into the base of the second metatarsal is often utilized to reduce the diastasis and aid healing of Lisfranc injuries. Also procedures such as a midfoot or a Lapidus arthrodesis require adequate implant-bone purchase in the medial cuneiform. The medial cuneiform contains cancellous bone of varying density. Knowledge of density variation may be helpful for implant usage and manufacturing of area specific implants. METHODS: In 60 randomly selected patients, mean computed tomography (CT) intensity in Hounsfield units was measured at 12 sampled locations within the medial cuneiform and served as a proxy for bone density. The patients' age, gender, and race were recorded. An analysis of variance (ANOVA) assessed the effect of age, gender, race, and sample site on bone density. Statistical testing assumed 95% level of confidence. RESULTS: ANOVA showed age, gender, and sample site had significant effects (P < .001) on bone density, though race had no significant effect (P = .28). The distal-dorsal-lateral (DDL) site was significantly denser than all other sites (P < .001) except the middle-dorsal-lateral (MDL) (P = .53). The proximal-plantar-lateral (PPL) site was significantly less dense than all other sites (P < .001) except the middle-plantar-lateral/medial and the proximal-plantar-medial sites (P < .14). A general trend of density increasing in the distal and dorsal directions was evident, and within the dorsal sites there was a trend of increasing density in the lateral direction. CONCLUSION: This is the first study to date to measure density of the medial cuneiform using living subjects. The sample size of 60 patients was also the largest of any study measuring density of this bone. We conclude that the densest area of the medial cuneiform is the most anterior, dorsal, and lateral portion. CLINICAL RELEVANCE: The findings of this study may indicate the most optimal area for implant purchase in the medial cuneiform when reducing the diastasis between the base of the second metatarsal and medial cuneiform and for stabilization of the medial column.