Editorial Commentary: If You Can't See It, You Can't Treat It: Proper Hip Radiographic Views Are Critical

Posterior Ankle Impingement: It's Not Only About the Os Trigonum

Background

Os trigonum and Stieda process are common etiologies for posterior ankle impingement syndrome (PAIS), and diagnosis is typically made by radiographs, computed tomographic, or magnetic resonance imaging. However, these static tests may not detect associated soft tissue and bony pathologies. Posterior ankle and hindfoot arthroscopy (PAHA) is dynamic, providing at least ×8 magnification with full anatomical visualization. The primary aim of this study was to report the prevalence of associated conditions seen with trigonal impingement treated with PAHA.

Methods

In this retrospective comparative study, patients who underwent PAHA for PAIS due to trigonal impingement, from January 2011 to September 2016, were reviewed. Concomitant open posterior procedures and other indications for PAHA were excluded. Demographic data were collected with pre- and postoperative diagnosis, arthroscopic findings, type of impingement, location, associated procedures, and anatomical etiologies. Trigonal impingements were divided in os trigonal or Stieda and subgrouped as isolated, with flexor hallucis longus (FHL) disorders, with FHL plus other impingement, and with other impingement lesions.

Results

A total of 111 ankles were studied-74 os trigonum and 37 Stieda. Isolated trigonal disorders accounted for 15.3% of PAIS (n = 17). Cases having associated conditions had a mode of 3 additional pathologies. FHL disorders were found in 69.4%, subtalar impingement in 32.4%, posteromedial ankle synovitis in 25.2%, posterolateral ankle synovitis in 22.5%, and posterior inferior tibiofibular ligament impingement in 19.8% of cases. Associated pathologies were observed in 58.6% of cases when FHL was not considered. Significant differences were noted comparing os and Stieda (isolated: 20.3% to 5.4%, P = .040; FHL plus others: 35.1% to 59.5%, P = .015).

Conclusion

Trigonal bone (os trigonum or Stieda) was found to cause impingement in isolation in a small proportion of cases even when the FHL was considered part of the same disease spectrum. This should alert surgeons when considering removing trigonal impingement. Open approaches may limit the visualization and assessment of associated posterior ankle and subtalar pathoanatomy, thus possibly overlooking concomitant causes of PAIS.

Level of Evidence

Level III, retrospective comparative study.

Intraoperative Automated Radiographic Visualization Tool Allows for Higher Accuracy of Cam Lesion Resection When Used by Novice Surgeons for Arthroscopic Femoroplasty: Lowering the Learning Curve

PURPOSE

To compare the accuracy of conventional fluoroscopy versus an intraoperative radiographic visualization tool in assisting a novice and experienced hip arthroscopist in comprehensive cam correction to a desired alpha angle (AA).

METHODS

A cadaveric study was performed using 28 hemi-pelvises with cam-type deformity (AA > 55˚) measured on anteroposterior, lateral, and Dunn-view radiographs. Two fellowship-trained hip arthroscopists each performed 14 arthroscopic femoroplasties. The specimens were randomly assigned: 14 of the procedures were performed by the experienced surgeon, with 7 using the automated radiographic visualization tool (Guided Femoroplasty) and 7 using routine fluoroscopy (Control). The same number of hips was assigned to the novice surgeon, completing 7 femoroplasties with and without the visualization tool. Each hip was imaged before and after femoroplasty in 6 different positions using intraoperative fluoroscopy to evaluate head-neck offset. Femoroplasty AAs were compared between groups with and without visualization tool use, as well as between surgeons. One-way analysis of variance analysis was performed to evaluate the consistency of cam resection.

RESULTS

For the experienced hip arthroscopist, comparison of Guide Femoroplasty and Control groups resulted in similar accuracy when compared to the controls, with post-femoroplasty AA averages ranging from 41.4° ± 3.8˚ to 44.8° ± 2.8˚ (P = .511) and 40.2° ± 5.3˚ to 45.6° ± 2.2˚ (P = .225), respectively. For the novice hip arthroscopist, the Guided Femoroplasty group had higher accuracy, with post-femoroplasty AA averages ranging from 42.8° ± 2.6˚ to 46.1° ± 7.2˚(P = .689) with and 39.8° ± 3.1˚ to 51.9° ± 8.1˚ (P = .001) without the visualization tool. Comparison of procedure time did not show any statistically significant difference between the use of the radiographic visualization tool and controls for either surgeon (P > .05 for all).

CONCLUSIONS

Femoroplasty with and without the use of automated radiographic visualization tool results in accurate cam resection when used by both the experienced and novice surgeon. However, higher accuracy was observed when resecting to a desired AA performed by a novice surgeon using the visualization tool. Additionally, use of the visualization tool did not result in longer procedure times for either surgeon.

CLINICAL RELEVANCE

The impact of incomplete cam resections and over-resection on patient outcomes in the literature has led to the recent development of automated intraoperative radiographic visualization tools that allow for assistance of cam resection accuracy for the treatment of femoroacetabular impingement syndrome. This cadaveric study demonstrates that femoroplasty with the use of an intraoperative automated radiographic visualization tool may result in more accurate cam resections.

Complete Capsular Closure Provides Higher Rates of Clinically Significant Outcome Improvement and Higher Survivorship Versus Partial Closure After Hip Arthroscopy at Minimum 5-Year Follow-Up

PURPOSE

To (1) compare the rates of reaching threshold hip-specific outcome scores for achieving the minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) in patients who underwent partial versus complete T-capsulotomy repair and (2) identify the failure rates in each group 5 years after undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS).

METHODS

Data from consecutive patients who underwent hip arthroscopy for FAIS performed by a single fellowship-trained surgeon from January 2011 to March 2013 were collected and analyzed. Baseline data, hip-specific outcomes, and clinical failure rates were recorded at a minimum of 5 years postoperatively. Patients with partial T-capsulotomy repair were matched 1:3 by age, body mass index, and sex to patients with complete T-capsulotomy repair. Threshold scores for achieving the MCID and PASS were calculated and compared between the 2 groups. Additionally, rates of revision and conversion to total hip arthroplasty (THA) were compared between the groups.

RESULTS

A total of 379 patients were available for analysis (39 partial and 340 complete repairs), with 100 patients included in the matching process (25 in the partial-repair group and 75 in the complete-repair group). Comparison of radiographic parameters, including the Tönnis grade, alpha angle, and lateral center-edge angle, between the 2 groups showed no statistically significant difference (P > .05 for all). Comparison of postoperative score averages between the partial- and complete-closure groups showed a significant difference in the Hip Outcome Score-Activities of Daily Living Subscale (85.4 ± 17.7 vs 94.6 ± 7.8, P < .001), Hip Outcome Score-Sports Subscale (76.6 ± 26.2 vs 89.3 ± 16.8, P = .034), modified Harris Hip Score (83.2 ± 19.7 vs 90.5 ± 11.2, P = .035), and visual analog scale pain score (24.5 ± 30.8 vs 13.4 ± 15.8, P = .035). A total of 65 complete-repair patients (95.6%) achieved the MCID for at least 1 outcome measure versus 18 patients with partial repair (78.3%) (P = .04). A total of 69 complete-repair patients (92%) achieved the PASS for at least 1 outcome measure versus 18 partial-repair patients (72%) (P = .017). Of the 39 partial-repair patients, 35.9% (n = 14) underwent revision or conversion to THA, as compared with 2.9% (n = 10) in the overall cohort.

CONCLUSIONS

At a minimum 5-year follow-up, patients with complete capsular closure after hip arthroscopy for FAIS show superior long-term outcomes and achieve higher rates of meaningful clinical success when compared with patients with partial capsular closure. Furthermore, patients with partial capsular repair undergo revision or conversion to THA at high rates.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

A Cadaveric Study of Cam-Type Femoroacetabular Impingement: Biomechanical Comparison of Contact Pressures Between Cam Morphology, Partial Femoral Osteoplasty, and Complete Femoral Osteoplasty

PURPOSE

To compare the biomechanical properties of the hip joint with an intact femoral cam lesion, partial cam resection, and complete cam resection.

METHODS

A cadaveric study was performed using 8 hemipelvises with cam-type morphology (alpha angle > 55°) and intact labra. Intra-articular pressure maps were produced for each specimen under the following conditions: (1) native cam morphology (intact), (2) cam morphology with incomplete resection (partial), and (3) cam morphology with complete resection (complete). By use of an open technique, resection of the superior portion of the cam morphology was performed with a 5.5-mm burr to create the partial resection, followed by the inferior portion to create the complete resection. In each condition, 3 biomechanical parameters were obtained: contact pressure, contact area, and peak force within a region of interest. Measurements were performed 3 times in each condition, and the average value was used for statistical analysis. Analysis of variance was used to compare biomechanical parameters between conditions.

RESULTS

A statistically significant difference was found between the pre- and post-resection alpha angles (62.2° ± 3.9° vs 40.9° ± 1.4°, P < .001). Repeated-measures analysis of variance showed that the normalized average pressure values of hips with complete resection of cam lesions were significantly lower than those of hips with incomplete femoral cam lesions and hips with intact cam morphology (100% vs 93.6% ± 8.3% and 82.6% ± 16.2%, respectively; P < .0001). The percentage reduction of contact pressure in the complete and partial groups was 17.4% and 6.4%, respectively, compared with the intact group. Contact area and peak force showed no statistically significant differences across the 3 conditions (P > .05).

CONCLUSIONS

Complete cam resection results in significantly lower intra-articular hip contact pressures than incomplete cam resection and native cam morphology in a cadaveric hip model. These observations underscore the importance of ensuring complete resection of femoral cam lesions in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome.

CLINICAL RELEVANCE

Previous studies have shown that the most common reason for revision hip arthroscopy in patients with femoroacetabular impingement syndrome is incomplete femoral cam resection during the index operation. This study shows biomechanical differences associated with partial cam resection compared with the complete cam resection state that may translate to persistent symptoms.

Patients With Borderline Hip Dysplasia Achieve Clinically Significant Improvement After Arthroscopic Femoroacetabular Impingement Surgery: A Case-Control Study With a Minimum 5-Year Follow-up

BACKGROUND

Hip arthroscopy for the treatment of femoroacetabular impingement syndrome (FAIS) in patients with borderline hip dysplasia (BHD) is becoming a more common practice. However, the literature on achieving meaningful outcomes at midterm follow-up, as well as predictors of these outcomes, is limited.

PURPOSE

To (1) compare the rates of achieving meaningful clinical outcomes between patients with and without BHD and (2) identify the predictors for achieving clinical success among patients with BHD 5 years after undergoing hip arthroscopic surgery for FAIS.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data from consecutive patients who underwent primary hip arthroscopic surgery with routine capsular closure for the treatment of FAIS between January 2012 and August 2014 were collected and retrospectively analyzed. Patients with BHD (lateral center-edge angle [LCEA] 20°-25°) were matched 1:2 by age (±1 year) and body mass index (BMI; ±5 kg/m²) to control patients with normal acetabular coverage (LCEA 25°-40°). Data collected included baseline and 5-year postoperative patient-reported outcomes. The minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) were calculated for each patient-reported outcome measure and compared between the 2 groups. A binary logistic regression analysis was used to identify significant predictors of achieving the MCID and PASS in the BHD group.

RESULTS

The MCID in the BHD group was defined as 9.6, 14.1, and 9.5 for the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, and modified Harris Hip Score, respectively. Threshold scores for achieving the PASS in both groups were 90.9, 76.6, and 81.9, respectively. A total of 88 patients were identified with having BHD and were matched to 176 controls. No statistical differences were identified for age, BMI, or sex. Both the BHD and the non-BHD groups had statistically significant increases in patient-reported outcome scores over the 5-year period, but the difference in both groups was not statistically significant (P > .05 for all). There was no statistical difference in the frequency of patients in the BHD and non-BHD groups achieving the MCID (86.6% vs 85.2%, respectively; P = .804) or PASS (76.0% vs 73.7%, respectively; P = .675) on at least 1 outcome measure. The logistic regression model demonstrated that being physically active (odds ratio [OR], 27.59; P = .005) and being female (OR, 14.64; P = .025) were independent predictors of achieving the MCID, while running (OR, 11.1; P = .002), being female (OR, 7.6; P = .011), and a larger preoperative LCEA (OR, 2.3; P = .001) were independent preoperative predictors of achieving the PASS.

CONCLUSION

The rates of achieving clinical success 5 years after undergoing arthroscopic treatment with capsular closure for FAIS were not significantly different between patients with BHD and those with normal acetabular coverage. Being physically active, running for exercise, female sex, and a larger LCEA were preoperative predictors of achieving clinical success at 5 years in patients with BHD.