Traction force for peroperative hip dislocation in hip arthroscopy

During Postless Hip Arthroscopy, Male Patients, High Body Mass Index, Low Beighton Scores, and Limited Range of Motion Require High Traction Force

PURPOSE

To determine the effects of demographic and anatomic factors on traction force required during postless hip arthroscopy.

METHODS

A prospectively collected database was retrospectively analyzed on patients undergoing hip arthroscopy by the senior author, including patient sex, age, body mass index (BMI), Beighton Hypermobility Score, hip range of motion in clinic and under anesthesia, hip dysplasia, acetabular version, and femoral version. All patients underwent postless hip arthroscopy under general anesthesia. At the initiation of hip arthroscopy, the traction force required to distract the hip joint was measured before and following interportal capsulotomy. Multiple regression analysis was performed to determine the effects of demographic and anatomic factors on measured distraction force.

RESULTS

In total, 352 hips (114 male, 238 female) were included with a mean age of 32.6 years and a mean BMI of 24.1 kg/m2. Mean initial traction force was 109 lbs and decreased to 94.3 lbs following capsulotomy (P < .0001). The starting traction force was significantly greater in male patients (P < .001), patients with a lack of hypermobility (Beighton Hypermobility Score of 0-2) (P = .026), and in patients with lower abduction (P < .001), lower internal rotation (P = .002), and lower external rotation (P = .012) on multiple regression analysis. When performing a subanalysis divided by sex, male patients with elevated BMI required significantly greater starting traction force (P = .014). Lateral center edge angle, sourcil angle, and the presence of hip dysplasia did not demonstrate a significant correlation with traction force.

CONCLUSIONS

Male patients, patients with reduced preoperative hip range of motion, patients with a lack of joint hypermobility, and male patients with an elevated BMI require greater initial traction force during postless hip arthroscopy.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Experimental assessment of pelvis slipping during postless traction for orthopaedic applications

BACKGROUND

The application of lower limb traction during hip arthroscopy and femur fractures osteosynthesis is commonplace in orthopaedic surgeries. Traditional methods utilize a perineal post on a traction table, leading to soft tissue damage and nerve neuropraxia. A postless technique, using high-friction pads, has been considered as a potential damage-free alternative. However, whether these pads sufficiently prevent patient displacement remains unknown. Thus, this study systematically assesses the efficacy of commercial high-friction pads (PinkPad and CarePad) in restraining subject displacement, for progressively increasing traction loads and different Trendelenburg angles.

METHODS

Three healthy male subjects were recruited and tested in supine and Trendelenburg positions (5° and 10°), using a customized boot-pulley system. Ten load disks (5 kg) were dropped at 15s intervals, increasing gradually the traction load up to 50 kg. Pelvis displacement along the traction direction was measured with a motion capture system. The displacement at 50 kg of traction load was analyzed and compared across various pads and bed inclinations. Response to varying traction loads was statistically assessed with a quadratic function model.

RESULTS

Pelvis displacement at 50 kg traction load was below 60 mm for all conditions. Comparing PinkPad and CarePad, no significant differences in displacement were observed. Finally, similar displacements were observed for the supine and Trendelenburg positions.

CONCLUSIONS

Both PinkPad and CarePad exhibited nearly linear behavior under increasing traction loads, limiting displacement to 60 mm at most for 50 kg loads. Contrary to expectations, placing subjects in the Trendelenburg position did not increase adhesion.

Hip Joint Venting Decreases the Traction Force Required to Access the Central Compartment During Hip Arthroscopy

Purpose

To investigate the effect of hip joint venting on the magnitude of traction force required to arthroscopically access the central compartment of the hip.

Methods

Patients who underwent hip arthroscopy for femoroacetabular impingement syndrome prospectively underwent an intraoperative traction protocol. Joint space was measured on fluoroscopic images obtained at 50 and 100 lbs of axial traction in the prevented and vented state, and joint space values were normalized to millimetric values using preoperative anteroposterior pelvis radiographs. Venting was performed by inserting a large gauge spinal needle into the hip joint through the hip capsule and removing the stylet. Joint space differences were compared with paired t-tests, Wilcoxon signed-rank tests, and McNemar tests.

Results

Fifty hips in 46 patients were included. Mean joint space before venting was 7.4 ± 2.6 mm and 13.3 ± 2.8 mm at 50 and 100 lbs of traction, respectively. Mean joint space after venting was 13.9 ± 2.3 mm and 15.5 ± 2.4 mm at 50 and 100 lbs of traction, respectively. Mean differences in joint space at 50 and 100 lbs were 6.5 mm (P < .001) and 2.2 mm (P < .001), respectively. Mean joint space at 50 lbs in the vented state was significantly greater than in the pre-vented state at 100 lbs (13.9 mm vs. 13.3 mm; P = .002). The increase in joint space between 50 and 100 lbs of traction was significantly greater in the prevented state than in the vented state (5.9 mm vs 1.6 mm; P = .021).

Conclusions

Venting the hip reduces the traction force necessary to arthroscopically visualize and instrument the central compartment of the hip by at least 50%. Further, residual negative pressurization of the hip joint remains after breaking the labral suction seal and venting effectively eliminates this phenomenon to aid in hip joint distraction at lower traction force.

Level of Evidence

Level IV, case series.

Distraction Gap Needed for Safe Central Compartment Access in Hip Arthroscopy

BACKGROUND

Sufficient distraction of the hip is the key to a safe central compartment (CC) approach in hip arthroscopy. However, an adequate distraction gap has not been scientifically identified.

PURPOSE

To determine the sufficient amount of distraction that could predict a successful CC access as well as to identify the risk factors for a failed or difficult CC access.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

All patients who underwent hip arthroscopy by a single surgeon between January 2018 and April 2019 were prospectively enrolled. We analyzed gaps of the hip on 4 C-arm fluoroscopic images: nondistraction, preoperative manual traction, preoperative maximal traction (without distension), and intraoperative maximal traction (at the end of CC procedures in a successful CC approach or after peripheral compartment procedures in a failed or difficult CC approach). A failed CC approach was defined as failure in introducing the anterolateral portal to the CC under arthroscopic control; a difficult CC approach was defined as the presence of an incomplete diagnostic round in the CC because of a small distraction. The amount of distraction was evaluated by the ratio of the distracted gap to the undistracted gap. Patients were classified into the successful CC access group (group 1) and the failed/difficult CC access group (group 2). The amount of distraction, demographic characteristics, and preoperative radiographic parameters were compared between the groups.

RESULTS

A total of 240 patients were included in this study. Group 1 consisted of 205 patients (113 males and 92 females; mean ± SD age, 34.5 ± 11.4 years), and group 2 consisted of 35 patients (27 males and 8 females; age, 32.5 ± 11.2 years). The preoperative joint space width was not significantly different between group 1 (mean ± SD, 3.89 ± 0.83 mm) and group 2 (3.68 ± 0.68 mm). The ratio of the amount of distraction at lateral gaps under all traction conditions was significantly greater in group 1 compared with group 2 (1.50 ± 0.54 vs 1.26 ± 0.35, respectively, under preoperative manual traction; 2.84 ± 0.76 vs 2.03 ± 0.63 under preoperative maximal traction; 3.36 ± 0.96 vs 2.50 ± 0.79 under intraoperative maximal traction). An increase of the lateral gap by >2.2 times (P < .001) under preoperative maximal traction and by >2.7 times (P < .001) under intraoperative maximal traction could predict successful CC access. Male sex (odds ratio [OR], 2.94; P = .017) and increased lateral center-edge angle (OR, 1.08 for every 1° increase; P = .004) were significant risk factors for failed/difficult CC access.

CONCLUSIONS

An increase of the lateral gap by >2.2 times during an unsterile traction test without joint distension could predict successful CC access. Male sex and increased lateral center-edge angle were risk factors for a failed or difficult CC access.

The traction force of the pulled limb in hip arthroscopic surgery is determined by stiffness coefficient which is significantly related to muscle volume

PURPOSE

To verify the relationship between muscle volume, lateral centre-edge angle (LCEA), alpha angle (AA), body mass index (BMI) and Beighton score with stiffness coefficient (SC). To analyse the difference of traction force at different physical states of hip joint capsule.

METHODS

Thirty-six patients who underwent hip arthroscopy operation were included. The volumes of some related muscles were measured in MRI images by 3D Slicer. We recorded and tested differences in traction force of five joint capsule physical states, including before (State 1) and after joint capsule puncture (State 2), after the establishment of anterolateral and mid-anterior approaches (State 3) and after incision of the joint capsule through these two approaches (States 4, 5). The correlation between muscle volume, BMI, LCEA, AA and SC was verified by Spearman test. Poisson regression was used to explain confounding variables.

RESULTS

The average force at State 1 was 531.8 N. There were significant differences in traction force between these five states (p < 0.001). There was a significant positive correlation between muscle volumes and SC (p < 0.001). BMI had no correlation with SC (n.s.). The preoperative LCEA of the affected side was correlated with SC (p = 0.043). AA and SC were not correlated (n.s.).

CONCLUSION

The physical states of the hip joint capsule affected traction force. Muscle volume rather than BMI is an ideal index to estimate preoperative traction force. LCEA affected traction force, whilst AA and Beighton score did not. Measuring the muscle volume can help estimate the most suitable traction force for the patient.

LEVELS OF EVIDENCE

IV.

Previous Arthroscopic Hip Surgery Increases Axial Distractibility Compared to the Native Contralateral Hip and May Suggest Instability

PURPOSE

To compare intraoperative hip joint distractibility between hips that previously underwent arthroscopic surgery and the contralateral hip with no history of surgical manipulation.

METHODS

Patients undergoing revision hip arthroscopy between April 2019 and December 2020, who previously underwent arthroscopic hip surgery for femoroacetabular impingement syndrome, were prospectively enrolled. Exclusion criteria were any contralateral hip surgery. Before instrumentation, fluoroscopic images of both hips were obtained at 25 lbs traction intervals up to 100 lbs. Total joint space was measured at each traction interval. Distraction was calculated as the difference between the baseline joint space and the total joint space at each subsequent traction interval. Wilcoxon signed ranks tests and McNemar tests were used to compare distraction between revision and native contralateral hips.

RESULTS

Forty-seven patients were included. Mean distraction of operative hips was significantly greater than mean distraction of nonoperative hips at traction intervals of 50 lbs (2.13 vs 1.04 mm, P = .002), 75 lbs (6.39 vs 3.70 mm, P < .001), and 100 lbs (8.24 vs 5.39, P < .001). Mean total joint space of operative hips was significantly greater than mean total joint space of nonoperative hips at traction intervals of 50 lbs (6.60 vs 5.39 mm, P < .001), 75 lbs (10.86 vs 8.05 mm, P < .001), and 100 lbs (12.73 vs 9.73, P < .001). A greater percentage of operative hips achieved all distraction thresholds, in 2-mm intervals up to 10-mm, at each traction interval.

CONCLUSIONS

In the majority of patients undergoing revision hip arthroscopy, previous arthroscopic hip surgery increases axial distractibility of the hip joint compared with the native contralateral hip at axial traction forces of 50-100 lbs. Increased axial distractibility following hip arthroscopy may be suggestive of hip instability and can be assessed on a stress examination with the patient under anesthesia.

LEVEL OF EVIDENCE

III, case-control study.

Longitudinal Capsulotomy in Hip Arthroscopy: A Safe and Feasible Procedure for Cam-Type Femoracetabular Impingement

Objective

To evaluate the surgical security, feasibility, and clinical efficacy of the longitudinal outside‐in capsulotomy in hip arthroscopic treatment for cam‐type femoracetabular impingement (FAI).

Methods

We retrospectively reviewed patients with cam‐type FAI who underwent hip arthroscopy in our institute from January 2018 to June 2019. All hip arthroscopic procedures were performed by one experienced surgeon in the same manner, except the fashions of capsulotomy. Fifty six patients with mean age of 39.1 and mean body mass index (BMI) of 24.5 were categorized into two groups according to the fashions of capsulotomy. Twenty six cases with longitudinal outside‐in capsulotomy were categorized into Group L, and 30 cases with transversal interportal capsulotomy were categorized into Group T as the control group. The demographic parameters were retrieved from medical documents and compared between the two groups. Surgical outcome including overall surgical time, traction time, complications, visual analogue score (VAS), and intraoperative radiation exposure were compared to investigate the security and feasibility. Radiographic assessment, and functional outcome were compared between the two groups to determine the clinical efficacy of the longitudinal capsulotomy.

Results

There was no significant difference in the demography and duration of follow‐up between the two groups. The overall surgical time demonstrated no significant difference between Group L and Group T (130.8 ± 16.6 min and 134.0 ± 14.7 min, P = 0.490). Significantly decreased traction time was found in Group L (43.2 ± 8.4 min and 62.2 ± 8.6 min, P < 0.001) compared to Group T. The Median of the fluoroscopic shot was 1 and 3 (P < 0.001). No major complications and reoperation were reported in both groups. The case of intraoperative iatrogenic injure was 0 (0%) and 6 (20%) in Group L and Group T respectively (P = 0.035), and the case of postoperative neurapraxia was 0 (0%) and 8 (26.6%) in Group L and Group T respectively (P = 0.017). The Median of postoperative VAS was 2 and 3 in Group L Group T (P = 0.002). The postoperative α angle was 42.3° ± 3.4° and 44.4° ± 3.5° in group L and group T respectively (P = 0.001). The postoperative iHOT‐12 score at final follow‐up was 79.3 ± 6.7 and 77.0 ± 7.9 respectively (P = 0.141).

Conclusion

Longitudinal outside‐in capsulotomy with less radiation exposure, reduced traction time, and reduced complications could be a safe and feasible procedure in arthroscopic treatment for cam FAI. Its clinical efficacy was not worse compared with traditional interportal capsulotomy in short‐term follow‐up.

Joint Venting Prior to Hip Distraction Minimizes Traction Forces During Hip Arthroscopy

PURPOSE

This study evaluates the effect of venting on distraction of the hip during arthroscopy on a post-free traction table for fixed traction forces ranging from 0 to 100 pounds (lbs).

METHODS

Patients underwent surgery by the senior author (S.K.A.) between November 2018 and July 2019. Inclusion criteria were primary hip arthroscopy requiring central compartment access. Patients were positioned in 10-15° Trendelenburg on a post-free traction table. Prior to instrumentation, fluoroscopic images of the operated hip joint were taken at 25-lb intervals from 0 to 100 lbs of axial traction. Traction was released for 15 minutes. Venting with 20 mL of air was performed and fluoroscopic images were repeated at all traction intervals. Joint displacement was measured at all intervals. An unvented control group underwent the same axial traction protocol for comparison.

RESULTS

Sixty-one consecutive patients underwent study protocol. Fifty-eight hips in 57 patients were included. Thirty-two (55.2%) were female; mean age was 31 ± 13 years and mean body mass index was 25.7 ± 6.2. Paired samples analysis demonstrated mean differences in distraction distance prior to and after venting of 0.27, 2.60, 4.09, 4.54, and 2.31 mm at 0, 25, 50, 75, and 100 lbs of traction, which were significant (P < .001) at all traction intervals. Significantly more vented hips distracted at least 10 mm at 25-100 lbs traction (P ≤ .001). An unvented control group showed no significant differences between the first and second traction application.

CONCLUSIONS

Venting prior to applying traction on a post-free traction table increases the distraction distance achieved for a given traction force at multiple levels of traction in comparison to the pre-vented state. Our results suggest venting the hip joint prior to the application of traction may serve to reduce the maximal amount of traction required to safely instrument the hip arthroscopically.

LEVEL OF EVIDENCE

IV, case series.

The effects of venting and capsulotomy on traction force and hip distraction in hip arthroscopy

This study evaluated the effects of venting and capsulotomy on the ratio of normalized distraction distance to traction force, correlating this trend with patient demographic factors. A ratio was chosen to capture the total effect of each intervention on the hip joint. During primary hip arthroscopy, continuous traction force was recorded, and fluoroscopic images were acquired to measure joint distraction before and after the application of traction, venting and interportal capsulotomy. Distraction–traction force ratios were compared using a one-sided paired t-test. A linear regression model was used to determine the relationship between age, sex and body mass index and pre- and post-intervention distraction–traction force ratios. Seventy-two adult patients and 73 hips were included. There was an increase in hip distraction with a decrease in traction force post-venting and capsulotomy (both P’s <0.001). Mean normalized distraction distance increased 1.5% of femoral head size after venting and an additional 2.2% of femoral head size after capsulotomy. Mean traction force decreased 2.2% (14.7 N) after venting and 2.3% (15.3 N) after capsulotomy. Female sex significantly correlated with larger differences in both pre- and post-venting capsulotomy ratios. Venting and capsulotomy both independently improve the ratio of normalized distraction distance to traction force when performed in vivo. However, the effect sizes of each intervention are small and of questionable clinical significance. Specifically, when adequate distraction for safe surgical hip access cannot be obtained despite application of significant traction force, venting and capsulotomy after the application of traction may not afford substantial improvement.