Biomedical Engineering Reference
In-Depth Information
12.6.2
Influence of Structural Failure
Rotator cuff repair has a long history of largely good to excellent results, often in
spite of structural failure of the repair. However, range of motion and strength are
generally compromised to some extent with an unhealed cuff. This clinical scenario
often results in a painful shoulder with functional disability. This is particularly
important in the younger (ages 40-60 years) patient population, which is generally
still of working age. Patients with manual labor jobs, especially those that require
shoulder level or overhead activity, and those with high recreational shoulder
demands do poorly in the setting of a failed repair.
Gerber et al. reported a series of 27 patients after open rotator cuff repair [ 56 ].
At a minimum of 2-year follow-up, 17 patients healed their tear and had an
excellent outcome. The patients with re-tears had a poorer outcome based on
Constant score, subjective shoulder value, pain, and ability to perform activities
of daily living. A series of 20 patients with known structural failure were evaluated
at 3-year follow-up [ 57 ]. Overall, outcomes were improved over preoperative
values. Rotator cuff tendons and muscles were evaluated by MRI and compared
to preoperative studies. Fatty degeneration increased over time in the supraspinatus
and infraspinatus muscles. Muscle atrophy was also seen in the supraspinatus.
Glenohumeral arthritis was also increased over time. Seventeen of the patients
were very satisfied or satisfied, and poorer outcomes correlated with larger tear size,
severity of fatty degeneration of the muscles, and the presence of arthritis. This
same group of patients was reevaluated 9 years after surgery [ 32 ]. Overall, the
clinical improvement seen initially did not deteriorate, despite increased fatty
degeneration in the muscles.
Zumstein et al. reported a series of 27 patients at 3 and 9 years following open
rotator cuff repair [ 58 ]. Thirty seven percent were re-torn at 3 years and 57% were
re-torn at 9 years. The patients with an intact repair had better results, as measured
by outcome score and strength. Fatty degeneration progressed in all torn tendons.
The size of re-tears progressed over the time interval studied. Healed repairs
appeared to protect against progressive fatty degeneration. Interestingly, the same
group of investigators reported on clinical and structural results after repair of
single tendon tears and found that repair may halt the atrophy of the supraspinatus,
but not reverse it [ 31 ]. Similarly, fatty degeneration either remained stable or
progressed, even in patients with healed tears. Further investigation is necessary
to elucidate the pathophysiology of these muscle changes, as well as the potential
effect of repair.
Dodson et al. followed a group of patients with known structural repair-site
failures an average of 3 years after repair [ 59 ]. The initial good clinical results did
not decrease over time; however, range of motion and strength measurements
decreased. The size of the re-tear increased and none of the tears healed. Muscle
architecture was not evaluated in this study. Miller et al . examined rotator cuff
repairs with ultrasound for repair-site integrity at regular intervals for 2 years after
surgery [ 60 ]. All tears were originally greater than 3 cm. Forty-one percent of the
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