Nathan Faulkner MD, Donna Blankenbaker MD, James Keene, MD Division of Sports Medicine, Departments of Orthopedic Surgery and Radiology

University of Wisconsin, Madison, Wisconsin, USA

The authors, (Nathan R. Faulkner, MD, Donna G. Blankenbaker, MD James S. Keene, MD) have no financial relationships to disclose

SIGNIFICANCE OF MRI FINDINGS OF ILIOPSOAS ATROPHY AFTER ARTHROCOPIC TENOTOMIES

This study describes the outcomes of 20 patients that had arthroscopic iliopsoas tenotomies at the lesser trochanter and postoperative MRI’s documenting iliopsoas muscle atrophy.

Although iliopsoas muscle atrophy is a known consequence of open tendon releases, the presence, severity, and significance of psoas atrophy after arthroscopic tenotomies has not been reported.

INTRODUCTION

PATIENTS AND METHODS:

Patients: Twenty who had MRA’s preoperatively and at 0.5 to 5 years after lesser trochanteric iliopsoas tenotomies are the basis this study. Three musculoskeletal radiologists independently reviewed the MRA’s.

Methods: The three radiologists graded the muscle atrophy from 0 (no fat) to 4 ( ≥75% fat infiltration). For all MR evaluations, atrophy was considered present if reported by two of the three radiologists.

Grade 4: 75% Fat Grade 0: No Fat Grade 3: 50% Fat

ASSESSMENT OF OUTCOMES

Clinical exams: preop, 6, and 12 months postop.

Outcomes: assessed with Harris hip scoring system.

Table III: The Modified Harris Hip Scoring System___ Pain (points) 44 None/ignores 40 Slight, occasional, no compromise in activity 30 Mild, no effect on daily activity, pain after activity, 20 Moderate, tolerable, makes concessions 10 Marked, serious limitations 0 Totally disabled Function: Gait Functional Activities Limp Stairs 11 None 4 Normally 8 Slight 2 Normally with banister 5 Moderate 1 Any method 0 Severe 0 Not able 0 Unable to walk Socks/Shoes Support 4 With ease 11 None 2 With difficulty 7 Cane, long walks 0 Unable 5 Cane, full time Sitting 4 Crutch 5 Any chair, 1 hour 2 2 canes 3 High chair, ½ hour 0 2 crutches 0 Unable to sit, ½ hour 0 Unable to walk Distance Walked Public Transportation 11 Unlimited 1 Able to enter 8 6 blocks 0 Unable to enter 5 2-3 blocks 2 Indoors only 0 Bed and chair Total Points ________ x 1.1 Total Score* ________ * The multiplier (1.1) is used to give a total possible score of 100 points

SURGICAL PROCEDURES

All patients also had their iliopsoas tendon released at the lesser trochanter. Postop, they had hip flexor weakness and used crutches (4 weeks) until the tendon re-attached and they gained active hip flexion.

All hip arthroscopies were performed supine as described by Byrd; Thus, the central & peripheral compartments were scoped, labral tears excised/repaired and osteoplasties done to treat bony impingement.

The % of patients with atrophy and the average grade of atrophy for each hip muscle is as shown. In 7 of the 20, there was a gap in the tendon, in 10 (50%) tendon was distorted, and in 3, it appeared normal.

RESULTS Average length of time from iliopsoas release to postoperative MR arthrogram was 1.9 years (range 0.5 to 5 years); 8 were done within the first year, 7 at 1-2 years, and 5 at 3-5 years after the tenotomy.

Muscle % with Atrophy Average Grade

Iliacus 85% 1.9

Psoas 75% 2.9

Quadratus 10% 1.8

Gluteus Maximus 25% 1.3

Preop: Tendon Intact

Post-op: Disrupted

RESULTS

Average MHHS scores for the 8 patients with grade 4 atrophy was 79 points; Average scores for the 6 patients with grade 2-3, and the 6 patients with grade 1 atrophy were 84 and 89 points, respectively.

Grade: 4

Grade: 2-3

84 89

Grade: 1

79

One-year MHHS scores

None of the patients had preoperative atrophy. Postop, 8 patients had grade 4, 6 had grade 2-3, and 6 had grade 1 atrophy; 80% had atrophy in both the iliacus & psoas muscles; Grade 4 atrophy seen 3 years postop.

Preop MRA No Atrophy Post-op (20 mos.): Grade 3

RESULTS

Table III: The Modified Harris Hip Scoring System___ Pain (points) 44 None/ignores 40 Slight, occasional, no compromise in activity 30 Mild, no effect on daily activity, pain after activity, 20 Moderate, tolerable, makes concessions 10 Marked, serious limitations 0 Totally disabled Function: Gait Functional Activities Limp Stairs 11 None 4 Normally 8 Slight 2 Normally with banister 5 Moderate 1 Any method 0 Severe 0 Not able 0 Unable to walk Socks/Shoes Support 4 With ease 11 None 2 With difficulty 7 Cane, long walks 0 Unable 5 Cane, full time Sitting 4 Crutch 5 Any chair, 1 hour 2 2 canes 3 High chair, ½ hour 0 2 crutches 0 Unable to sit, ½ hour 0 Unable to walk Distance Walked Public Transportation 11 Unlimited 1 Able to enter 8 6 blocks 0 Unable to enter 5 2-3 blocks 2 Indoors only 0 Bed and chair Total Points ________ x 1.1 Total Score* ________ * The multiplier (1.1) is used to give a total possible score of 100 points

Average age higher in grade 4: • Grade 1: 26 years • Grade 4: 41 years (p < 0.05)

Average scores lower grade 4: • Grade 1: 89 points • Grade 4: 79 points

Grade: 1

Grade: 4

26

41

79

89

Age 1-year scores

Differences in averages due to lower scores in categories of Gait & Distance Walked (6 vs 10 pts)

DISCUSSION

Atrophy also was seen in 25% of the gluteus maximus muscles (arrow). We speculated that this unexpected atrophy was due to the lack of opposition from the atrophied iliacus and psaos muscles.

In our 20 patients, post-tenotomy atrophy was most common in the psoas (85%) and iliacus (65%) muscles. The severity of atrophy also was greater in the psoas (psoas grade 2.9; iliacus grade 1.9).

Muscle % with Atrophy

Average Grade

Iliacus 85% 1.9

Psoas 75% 2.9

Quadratus 10% 1.8

Gluteus Maximus 25% 1.3

DISCUSSION

However, an important limitation of our study is that all 20 patients had repeat MRA’s for recurrent hip pain. We do not know if our findings would apply to asymptomatic patients after psoas tenotomies.

Our results document that older patients develop more severe atrophy (grade 4) and that patients with high grade atrophy have lower one-year MHHS than those with lower grades of atrophy.

Average age higher in grade 4: • Grade 1: 26 years • Grade 4: 41 years (p < 0.05)

Average scores lower grade 4: • Grade 1: 89 points • Grade 4: 79 points

Patients Grade of Atrophy

Pre-op Scores

6-month scores

Scores at MRA

8 4 31.6 70.26 79.08

6 2-3 41.98 78.1 83.6

6 1 35.2 81.4 81.4

DISCUSSION

Three patients (15%) had no distortion or gaps in their tendons on their follow-up MRA’s 15-22 months after their tenotomies (arrow, D above), but they had persistent psoas and iliacus atrophy as shown.

As noted above, 35% of the pateints had a complete gap (persistent disruption of the tendon) at ≤ 9 months postop, and 50% had continuity but distortion of the tendon five years after tenotomy.

Preop: Tendon Intact

Post-op: Gap in Tendon

Grade 3 Psoas Atrophy

Tendon Intact @ 22 mos.

Preop: Tendon Intact

Grade 2 Psoas Atrophy

A C

D

CONCLUSIONS

Significant (Grade 4) Iliopsoas muscle atrophy occurs and persists up to 5 years after arthroscopic iliopsoas tenotomies.

Of the 20 patients with MRI-documented muscle atrophy, 8 had grade 4 and 16 had atrophy of both the iliacus and psoas muscles.

Grade 4 atrophy was more common in older patients and they had lower MHHS (79 vs. 89 points) than those with minimal atrophy.

Patients with intact, normal appearing tendons on their follow-up MRI’s also had significant (Grade 2-3) iliopsoas muscle atrophy.

Grade 4: 75% Fat Tendon Intact @ 22 mos.

Grade 2 Psoas Atrophy

University of Wisconsin Sports Medicine Center