Sub-Acromial Decompression (SAD) for impingement has a failure rate of 5–20%. We used MRI to see whether SAD failure is associated with muscle wasting or fatty degeneration in the rotator cuff. Fifty one patients with impingement were assessed using MRI pre- and post-op. Following arthroscopic SAD, seven patients with cuff tears were excluded. This study reviews the pre-op and 6 month post-op MRIs of the remaining 44 patients (25 males; 19 females) and also 17 additional MRIs obtained at three years post-op. MRI assessment was performed by an experienced radiologist using Zanetti’s muscle bulk assessment with values expressed as standard deviations from an age matched mean and Goutallier’s fatty degeneration assessment graded 0 to 4. There was a wide range of pre-op muscle bulk values (SupraSpinatus minus;2.4 to +3.4; SubScapularis minus;2.1 to +4.8; and InfraSpinatus/ Teres Minor minus;1.1 to +5.7). Comparing post-op with pre-op there was a gradual trend towards a reduced muscle bulk for each muscle after surgery but to a limited extent only (<
0.5SD). Pre-op fatty degeneration of SS and IS was grade 2 in about a half with a mild increase with time post-op (SS pre=50%, 6/12 and 3 years=59%; IS pre=45%, 6/12=43% and 3 years=59%). There was a similar age distribution for grades 1 and 2. Only three of the patients were a clinical failure at 6 months but this increased to five of the 17 patients scanned at 3 years. Predicting these failures was not possible based on the pre-op MRI data. The high initial success of SAD was not accompanied by an overall increase in muscle bulk or quality of the muscle at 6 months. The progressive loss of muscle bulk and quality over 3 years was accompanied by an increased clinical failure rate.
Clinical examination. Constant Scoring. Cybex testing of the rotator cuff muscles. MRI scans. Arthroscopic examination followed by arthroscopic SAD. Standard post-op rehab. Tests were repeated at 6 months, and in 17 patients again 3 years after surgery.
SAD still provides good pain relief Muscle power increases post-operative but tends to plateau or slightly decrease after 3 years Dynamic muscle power measurement is recommended for accurate assessment. Other Cybex measurements (Torque) had little relation to clinical outcome. Constant score does not accurately assess changes in muscle power.
The Halder Nail was introduced into the UK in 1994 and the inventor has recently reported his results (Halder et al, 2001
All tests were repeated at the minimum of 6 (average 6.3) months after the operation.
CLINICAL
- 23 (95.83%) improved subjectively, and were back to their normal daily routines. - The average improvement in VAS scoring was an average of 3.5 (2–7)) - Impingement signs disappeared in 23 patients (95.83%) - Average increase in Constant score was 23 points, from 53.5 to 76.5.Average pain increased from 7.5 to 9, ADL from 5.5 to 6, hand position from 7 to 8, range of motion from 21.5 to 37 &
power from 9 to 17. Dynamometer Muscle testing (All measurement of power was done in watts)
A-Abduction power increased from an average of 14.5 to 32.9, Adduction from 17 to 42 b- At maximal adduction internal rotators increased from 25.5 to 34.55, external rotators from 20.25 to 30.85 and c- At 90° abduction the internal rotators increased from 19.55 to 31.3, and the external rotators from 16.6 to 21.95
-ASD provides good pain relief -Most patients return to work before the end of 6 months period; however there seems to be a tendency for further improvement after the 6 months period. - Muscle power increases post-operative but with individual variation -Dynamic Power assessment is preferable to the Constant Score method, as power is measured in Watts, and can test below 90° of elevation. -Power measurement is the only parameter directly related to the clinical outcome of ASD.
