Abstract
Background: Epidemiologic studies have demonstrated substantial
variations in per capita rates of many surgical procedures, including rotator
cuff repair. The purpose of the current study was to characterize orthopaedic
surgeons' attitudes concerning medical decision-making about rotator cuff
surgery and to investigate the associations between these beliefs and reported
surgical volumes.
Methods: A survey was mailed to randomly selected orthopaedic
surgeons listed in the American Academy of Orthopaedic Surgeons directory.
Only individuals who had treated patients for a rotator cuff tear, or had
referred patients for such treatment, within the previous year were asked to
complete the two-page survey. The survey comprised fifteen questions regarding
clinical opinion, including four regarding hypothetical cases. Clinical
agreement was defined as >80% of the respondents answering similarly.
Results: Of the 1100 surveys that were mailed, 539 were returned (a
response rate of 49%). Of the 539 respondents, 316 (58.6%) had treated or
referred patients with a rotator cuff tear in the previous year. There was a
significant negative correlation between the surgeon's estimation of the
failure rate of cuff repairs in the United States and that surgeon's procedure
volume (r = -0.21, p = 0.0003), indicating that surgeons with a lower
procedure volume are more pessimistic about the results of surgery than are
those with a higher procedure volume. Arthroscopic, mini-open, and open cuff
repairs were preferred by 14.5%, 46.2%, and 36.6% of the respondents,
respectively. Surgeons who performed a higher volume of procedures were less
likely to perform open surgery (p < 0.0001). There was clinical agreement
regarding only four of the nine clinical questions and none of the four
questions about the hypothetical vignettes.
Conclusions: We found significant variation in surgical
decision-making and a lack of clinical agreement among orthopaedic surgeons
about rotator cuff surgery. There was a positive correlation between the
volume of procedures performed by the surgeon and the surgeon's perception of
outcome, with surgeons who had a higher procedure volume being more
enthusiastic about rotator cuff surgery than those who had a lower procedure
volume.
Substantial variation in the per capita rate of surgical procedures (area
variation) is ubiquitous across many levels of geography and has been
demonstrated for many musculoskeletal
conditions1-9.
There are several theories about the possible cause(s) of area variation. One
explanation is the "professional uncertainty hypothesis,"
popularized by Wennberg and Gittelsohn, which postulates that area variation
is the result of clinical uncertainty regarding the management of conditions
for which there is no clinical consensus about treatment
options10.
Alternatively, Chassin proposed the "enthusiasm hypothesis," which
postulates that the variation is due to differences in surgeons' enthusiasm
for procedures, which may not be
evidence-based11.
In describing geographic variations in the rates of three common shoulder
procedures—total shoulder replacement, humeral head replacement, and
rotator cuff repair—Vitale et al. reported that the rates varied by
state by as much as tenfold and that rotator cuff repair had the highest
variation3. The
variation was not related to surgeon density or surgeon subspecialty but was
inversely related to population density. The indications for rotator cuff
repair are unclear because the natural history of rotator cuff disease is not
well documented12.
Numerous studies have shown that many rotator cuff tears are completely
asymptomatic13-17.
Furthermore, the literature contains contradictory data regarding the efficacy
of repair and the role of decompression. These factors, along with reports of
low postoperative healing
rates18-20,
make it difficult to define the appropriate indications for rotator cuff
repair. Hence, divergences in clinical opinions may be responsible for
variations in the utilization of these surgical procedures, as has been
observed to be the case for knee replacement and lumbar disc
excision21-23.
The purpose of this study was to characterize the variation in orthopaedic
surgeons' attitudes concerning medical decision-making about rotator cuff
surgery and to investigate the association between those beliefs and reported
surgical volumes.
Atwo-page questionnaire was developed to quantify surgeons' opinions
about surgical decision-making regarding the treatment of rotator cuff lesions
(see Appendix). The questionnaire was reviewed and revised by a
multidisciplinary panel consisting of an expert in medical decision-making
(B.R.S.), an epidemiologist (S.L.), two shoulder surgeons (R.F.W. and E.C.J.),
and a third shoulder surgeon with training in clinical epidemiology and
experience with physician surveys (R.G.M.). Final iterations of this survey
were first pilot-tested by four additional shoulder surgeons from different
geographic regions. Pilot testing suggested that the survey was understandable
and could be completed quickly (in approximately five minutes on the average).
Feedback from the pilot-test subjects regarding questions was incorporated
into the final survey.
Surgeons were asked whether they had "treated patients or referred
patients for treatment for rotator cuff tears" within the past year.
Surgeons who answered "no" to this question were excluded from
subsequent analyses. The remaining surgeons were then asked how many rotator
cuff repairs they had performed in the past year and whether they preferred an
arthroscopic, mini-open, or open method of repair for a 2-cm full-thickness
tear. The surgeons were also asked to estimate "the failure rate
(defined as patient dissatisfaction) for all patients undergoing rotator cuff
repair in the USA this year." Tertiles were used to define unbiased
thresholds to determine whether the surgeon's volume of rotator cuff repairs,
performed in the past year, was low, medium, or high. Tertiles are a type of
percentile that divides a distribution into three equal groups, with each
group containing one-third of the values; however, if the total number of
values is not a multiple of 3, one of the groups will have an extra value.
The survey was divided into two major sections: four questions regarding
hypothetical case
presentations24 and
eleven questions about factors that might affect surgical decision-making.
Case Presentations
The hypothetical case presentations, in which it was stated that the
rotator cuff tear had been confirmed by magnetic resonance imaging, were
designed to address four different clinical presentations of cuff lesions that
are potentially controversial. They included (1) a painful, partial-thickness
tear in a laborer who had sustained a traumatic injury four months previously,
(2) a full-thickness tear in a laborer with mild weakness and little pain who
had sustained a traumatic injury three months previously, (3) a full-thickness
tear in a fifty-five-year-old man with a one-year history of mild discomfort,
and (4) a large, retracted tear with fatty infiltration of the cuff muscles in
a patient who had sustained a traumatic injury one week previously. For each
of the four hypothetical patients, the surgeons were asked to choose one of
the following options: (1) no surgery, physical therapy; (2) no surgery, a
cortisone injection; (3) surgery without cuff repair; and (4) surgery with
cuff repair. In subsequent analysis, these four categories were collapsed into
discrete responses (operative management and nonoperative management).
Factors That Affect Surgical Decision-Making
Of the eleven questions about factors that might influence decision-making
regarding rotator cuff surgery (e.g., patient expectations, role of physical
therapy, role of corticosteroid injection, relationship between cuff disease
and shoulder osteoarthritis, and potential progression of the tear), nine were
answered with use of a 5-point Likert scale (strongly disagree, disagree,
indifferent, agree, and strongly agree). In subsequent analysis, these
responses were collapsed into a 3-point scale (agree, indifferent, and
disagree). Of the remaining two questions, one requested a numerical response
concerning the maximum recommended number of steroid injections, and the other
was a multiple-response question that addressed factors affecting the
patients' ability to participate in surgical decision-making.
Clinical agreement has been inconsistently and somewhat arbitrarily defined
in the literature. Wright et al. defined agreement as >90% of physicians
answering similarly on a
survey23,25,
whereas others have suggested that a value of >95% indicates strong
agreement and a value of >60% indicates general
agreement26. Marx
et al. defined clinical agreement as 80% of surgeons answering
similarly27, and
for the purposes of the study we defined clinical agreement as >80%
agreement according to the criteria used by Marx et al.
A sampling frame of orthopaedic surgeons was constructed with use of the
2002 membership directory of the American Academy of Orthopaedic Surgeons
(AAOS), which contains contact information for approximately 20,756 surgeons.
A total of 1100 orthopaedic surgeons were randomly selected from this frame to
receive a survey by mail. A cover letter encouraging participation and signed
by one of the authors of this study (R.F.W.) was included in the
mailing28.
For statistical analyses, the Mantel-Haenszel chi-square and Fisher exact
tests were used to compare proportions and an independent-samples t test and
one-way analysis of variance were used to compare mean values. Correlations
were measured with use of the Spearman correlation coefficient. All analyses
were performed with SAS for Windows 9.0 software (Cary, North Carolina).
Of the 1100 surveys that were mailed, 539 were returned (a response
rate of 49%) (Fig. 1). There
was no significant difference between the surgeons who responded and those who
did not respond in terms of geographic region (Fisher exact test, p = 0.73).
Years of membership in the AAOS was used as a surrogate for years in practice.
Respondents had been in practice for an average of eighteen years and
nonrespondents, for an average of twenty years (t test, p < 0.0001).
Of the 539 surgeons who returned the survey, 316 (58.6%) indicated that
they had treated patients with a rotator cuff tear in the past year.
Twenty-one of the 316 had not performed any rotator cuff surgery in the past
year, and five left the question regarding the number of rotator cuff repairs
blank. These twenty-six surveys were excluded from subsequent analysis. The
290 respondents who reported that they had performed rotator cuff surgery in
the past year form the basis of the survey analysis. Dividing the reported
surgical volumes into tertiles provided a threshold of less than twenty cases
per year for a low-volume practice, twenty to thirty-nine cases per year for a
mid-volume practice, and forty or more cases per year for a high-volume
practice.
There was a significant negative correlation between the surgeon's
estimation of the failure rate in the United States and his or her surgical
volume (r = -0.21, p = 0.0003), with surgeons who performed a lower
volume of operations being more pessimistic about the results of rotator cuff
surgery than those who performed a higher volume of operations. The mean
estimated failure rate (and standard deviation) was 15.3% ± 11.5%.
Arthroscopic, mini-open, and open cuff repairs were preferred by 14.5%, 46.2%,
and 36.6% of the surgeons, respectively
(Table I). The mean number of
years in the AAOS was 9.4, 11.8, and 16.2 for surgeons indicating that their
preferred method of cuff repair was arthroscopic, mini-open, and open,
respectively. A significant difference between these means was identified by
one-way analysis of variance (p < 0.001), and a post hoc Duncan test (alpha
level = 0.05) demonstrated that surgeons who preferred an open cuff repair had
been in practice longer than those who preferred the arthroscopic or mini-open
technique. A significant inverse relationship was noted between the
"invasiveness" of the preferred repair and the volume of
procedures that the surgeon had performed (p < 0.0001). Those who performed
a higher volume were less likely to prefer open surgery. Neither the preferred
type of cuff repair nor the surgical volume appeared to be related to
geography, as no differences were observed according to the United States
geographic region (South, Northeast, West, or Midwest) when results were
stratified by volume tertile (p = 0.48) or by preferred type of repair (p =
0.09).
There was clinical agreement regarding four of the nine clinical questions
(Table II) and none of the four
questions about the hypothetical vignettes
(Table III). When the responses
to the questions about the four hypothetical vignettes
(Table IV) were stratified
according to surgical volume tertile, a significant trend was found for
surgeons with a higher procedure volume to be more likely to choose operative
management for vignettes 1, 2, and 3 and less likely to choose operative
management for vignette 4 (Table
V).
When the nine questions regarding factors that affect surgical
decision-making were stratified by surgical volume tertile, significant trends
were found for two questions (see Appendix): surgeons with a higher procedure
volume were more likely to agree that patients should expect to have a normal
shoulder after rotator cuff repair and that a major reason to repair the
rotator cuff is to prevent progression of the tear.
Five (1.7%), sixty-five (22.4%), 157 (54.1%), forty-three (14.8%), and
seventeen (5.9%) of the respondents indicated that one, two, three, four, and
five or more steroid injections, respectively, could be safely given in one
year; three respondents did not answer this question. There was a significant
negative correlation between the reported surgical volume and the respondent's
opinion about the number of steroid injections that can be given safely in a
year (r = -0.19, p = 0.005). In other words, surgeons with a higher
procedure volume were less enthusiastic about multiple steroid injections than
were surgeons with a lower procedure volume.
There was considerable disagreement among the surgeons regarding
most of the items in our survey. In fact, there was clinical agreement
regarding only four questions and regarding none of the questions about the
hypothetical case presentations. Eddy described three types of practice
policies: standards, guidelines, and
options29. Survey
items with =95% agreement are considered "practice standards,"
items with <95% but =60% agreement are considered "practice
guidelines," and items with <60% agreement are considered
"practice options." According to Eddy's conceptual framework, only
one item in our survey ("the expected frequency and duration of
postoperative rotator cuff rehab should be discussed with patients
preoperatively") could be considered a "practice standard,"
although ten items (including all four responses concerning the hypothetical
cases) could be considered "practice guidelines." This
disagreement probably contributes to the geographic variation in rates of
rotator cuff surgery.
Three potential sources of clinical disagreement among surgeons have been
proposed by Wright et
al.25: (1) lack of
evidence, (2) controversy about existing evidence, and (3) lack of awareness
and/or acceptance of existing evidence. The clinical disagreements described
in the current study probably reflect all three of these explanations. Several
authors have noted a lack of clinical evidence regarding partial and
full-thickness rotator cuff tears and that they have an unclear natural
history12,28,30,31.
Many aspects of rotator cuff surgery are still controversial, and several
studies have demonstrated conflicting results concerning such issues as
nonoperative management of full-thickness
tears32, the role
of
débridement33-37,
arthroscopic compared with open
techniques38-40,
and the role of
acromioplasty32.
Furthermore, even when good information is available in the literature,
surgeons may not have been exposed to that information or, if they have, they
may think that it is biased or flawed. These factors are probably influenced
by the amount of training in shoulder surgery that they have completed.
In keeping with the "enthusiasm hypothesis," surgeons who have
performed a higher volume of cuff repairs appear to be more enthusiastic about
them. The responses to the questions about three of the four hypothetical
cases showed a significant trend in which surgeons with a higher procedure
volume were more likely than those with a lower volume to select operative
management. This preference for operative intervention by surgeons with a high
procedure volume may be appropriate and lead to better outcomes. Conversely,
it is possible that the opinions of the surgeons with a low procedure volume
are more accurate and that a factor contributing to high surgical volume is
the surgeons' preference to operate. The opposite significant trend was noted
for vignette 4, which was intended to depict an acute injury at the site of a
chronic tear with fatty infiltration and, therefore, a potentially irreparable
injury. This trend could reflect the fact that surgeons with a lower procedure
volume did not appreciate the clinical scenario that the vignette intended to
depict either because of a lack of clarity of the vignette or the surgeon's
lack of knowledge of the available literature, or both.
Surgeons reporting a higher procedure volume in this study also estimated
the failure rate of cuff repairs in the United States to be lower. An inverse
relationship between reported volume and estimated failure rate, in which
surgeons with a higher procedure volume perceived the outcome of surgery to be
better than did those with a lower volume, has been shown in survey studies
regarding total knee
replacement25,26.
There are several possible reasons for this finding. First, surgeons who
believe that the surgical failure rate is low probably counsel patients
accordingly and therefore offer surgery to more patients. Second, surgeons
with a higher procedure volume may actually have lower failure rates
themselves and may believe that their failure rates are more representative of
average outcomes than they actually are.
We are aware of only two reports comparing the volume and outcome of
shoulder surgery, and both dealt with shoulder
arthroplasty41,42.
In both studies, in which administrative data were utilized, the patients of
surgeons with a high procedure volume had fewer complications and a shorter
length of stay in the hospital compared with patients of surgeons with a low
procedure volume. While there is a growing body of volume-outcome literature
documenting better outcomes in high-volume
centers43-47,
these results should be viewed with caution because the studies are limited by
the ecological
fallacy48, which
can occur when inferences are made at the individual level on the basis of
group-level data. For example, when measured at the patient level, the
proportion of normal appendices that are removed is higher when surgery is
delayed after the time of admission; however, when measured at the hospital
level, the proportion of normal appendices that are removed is lower when
surgery is
delayed49. Further
investigation is necessary to determine if the volume of cuff surgery is
related to the failure rate and the patient-relevant outcome.
This study has several limitations. First, case volume was determined in
our survey on the basis of the physicians' self-report, which is subject to
recall bias. However, there is no evidence to suggest that recall bias is
disproportionately greater for surgeons with a high procedure volume than it
is for those with a low volume. Our sampling frame was limited to members of
the AAOS, and, although we believe that a high proportion of rotator cuff
repairs are performed by AAOS members (the AAOS membership department
estimates that 96% of board-certified orthopaedic surgeons in the United
States are AAOS members), we were unable to independently confirm this
assumption. There was a small difference between the respondents and the
nonrespondents in terms of the mean years of membership in the AAOS (eighteen
and twenty years, respectively), but it seems unlikely that a mean difference
of two years would significantly affect the results. Differential
interpretation or misinterpretation of the questions may explain some of the
differences in the surgeons' responses; for example, the different approaches
to repair (arthroscopic, mini-open, and open) were not defined. We attempted
to reduce this bias by limiting the survey to two pages, to avoid respondent
fatigue, and by pilot testing the survey; however, limiting the survey length
precluded additional questions about factors that could influence responses,
such as educational background and fellowship training.
In summary, in our survey of orthopaedic surgeons, we found significant
variation in surgical decision-making and a lack of clinical agreement about
rotator cuff surgery. There was a positive correlation between surgical volume
and the surgeons' perceptions of outcome, with surgeons with a high procedure
volume appearing more enthusiastic about rotator cuff surgery than those with
a lower volume. Additional study of the influence of surgical volume on
decision-making and the outcome of rotator cuff surgery is warranted.
The entire questionnaire and the detailed responses broken down by surgical
volume are available with the electronic versions of this article, on our web
site at
(go to the article citation and click on "Supplementary Material")
and on our quarterly CD-ROM (call our subscription department, at
781-449-9780, to order the CD-ROM). ?
Birkmeyer JD, Sharp SM, Finlayson SR,
Fisher ES, Wennberg JE. Variation profiles of common surgical procedures.
Surgery.1998;124:
917-23.124917
1998
[PubMed][CrossRef]
Wennberg JE. Variations in medical
practice and hospital costs. Conn Med.1985;49:
444-53.49444
1985
[PubMed]
Vitale MG, Krant JJ, Gelijns AC, Heitjan
DF, Arons RR, Bigliani LU, Flatow EL. Geographic variations in the rates of
operative procedures involving the shoulder, including total shoulder
replacement, humeral head replacement, and rotator cuff repair. J Bone
Joint Surg Am.1999;81:
763-72.81763
1999
Peterson MG, Hollenberg JP, Szatrowski
TP, Johanson NA, Mancuso CA, Charlson ME. Geographic variations in the rates
of elective total hip and knee arthroplasties among Medicare beneficiaries in
the United States. J Bone Joint Surg Am.1992;74:
1530-9.741530
1992
[PubMed]
Keller RB, Soule DN, Wennberg JE, Hanley
DF. Dealing with geographic variations in the use of hospitals. The experience
of the Maine Medical Assessment Foundation Orthopaedic Study Group. J
Bone Joint Surg Am.1990;72:
1286-93.721286
1990
Wright JG, Hawker GA, Bombardier C,
Croxford R, Dittus RS, Freund DA, Coyte PC. Physician enthusiasm as an
explanation for area variation in the utilization of knee replacement surgery.
Med Care.1999;37:
946-56.37946
1999
[PubMed][CrossRef]
McPherson K, Wennberg JE, Hovind OB,
Clifford P. Small-area variations in the use of common surgical procedures: an
international comparison of New England, England, and Norway. N Engl J
Med.1982;307:
1310-4.3071310
1982
[CrossRef]
McPherson K, Strong PM, Epstein A, Jones
L. Regional variations in the use of common surgical procedures: within and
between England and Wales, Canada and the United States of America. Soc
Sci Med [A].1981;15:
273-88.15273
1981
Weinstein JN, Birkmeyer JD. The
Dartmouth atlas of musculoskeletal health care. Chicago, IL: AHA;
2000.
2000
Wennberg J, Gittelsohn A. Variations in
medical care among small areas. Sci Am.1982;246:
120-34.246120
1982
[PubMed][CrossRef]
Chassin MR. Explaining geographic
variations. The enthusiasm hypothesis. Med Care.1993;31(5 Suppl):
YS37-44.31YS37
1993
[PubMed][CrossRef]
Yamaguchi K, Tetro AM, Blam O, Evanoff
BA, Teefey SA, Middleton WD. Natural history of asymptomatic rotator cuff
tears: a longitudinal analysis of asymptomatic tears detected sonographically.
J Shoulder Elbow Surg.2001;10:
199-203.10199
2001
[PubMed][CrossRef]
Yamaguchi K, Sher JS, Andersen WK,
Garretson R, Uribe JW, Hechtman K, Neviaser RJ. Glenohumeral motion in
patients with rotator cuff tears: a comparison of asymptomatic and symptomatic
shoulders. J Shoulder Elbow Surg.2000;9:
6-11.96
2000
[PubMed][CrossRef]
Codman EA, Akerson IB. The pathology
associated with rupture of the supraspinatus tendon. Ann Surg.1931;93:
348-59.93348
1931
[PubMed][CrossRef]
Goodman RS. Abnormal findings on
magnetic resonance images of asymptomatic shoulders. J Bone Joint Surg
Am.1996;78:
633.78633
1996
Milgrom C, Schaffler M, Gilbert S, van
Holsbeeck M. Rotator-cuff changes in asymptomatic adults. The effect of age,
hand dominance and gender. J Bone Joint Surg Br.1995;77:
296-8.77296
1995
[PubMed]
Miniaci A, Dowdy PA, Willits KR, Vellet
AD. Magnetic resonance imaging evaluation of the rotator cuff tendons in the
asymptomatic shoulder. Am J Sports Med.1995;23:
142-5.23142
1995
[PubMed][CrossRef]
Galatz LM, Ball CM, Teefey SA, Middleton
WD, Yamaguchi K. The outcome and repair integrity of completely
arthroscopically repaired large and massive rotator cuff tears. J Bone
Joint Surg Am.2004;86:
219-24.86219
2004
Harryman DT 2nd, Mack LA, Wang KY,
Jackins SE, Richardson ML, Matsen FA 3rd. Repairs of the rotator cuff.
Correlation of functional results with integrity of the cuff. J Bone
Joint Surg Am.1991;73:
982-9.73982
1991
Mansat P, Cofield RH, Kersten TE,
Rowland CM. Complications of rotator cuff repair. Orthop Clin North
Am.1997;28:
205-13.28205
1997
[CrossRef]
Langley GR, Tritchler DL,
Llewellyn-Thomas HA, Till JE. Use of written cases to study factors associated
with regional variations in referral rates. J Clin Epidemiol.1991;44:
391-402.44391
1991
[PubMed][CrossRef]
Vayda E, Mindell WR. Variations in
operative rates: what do they mean? Surg Clin North Am.1982;62:
627-39.62627
1982
[PubMed]
Coyte PC, Hawker G, Croxford R, Attard
C, Wright JG. Variation in rheumatologists' and family physicians' perceptions
of the indications for and outcomes of knee replacement surgery. J
Rheumatol.1996;23:
730-8.23730
1996
Vayda E, Mindell WR, Mueller CB. Use of
hypothetical cases to investigate indications for surgery. Can J
Surg.1981;24:
19-21.2419
1981
Wright JG, Coyte P, Hawker G, Bombardier
C, Cooke D, Heck D, Dittus R, Freund D. Variation in orthopedic surgeons'
perceptions of the indications for and outcomes of knee replacement.
CMAJ.1995;152:
687-97.152687
1995
[PubMed]
Tierney WM, Fitzgerald JF, Heck DA,
Kennedy JM, Katz BP, Melfi CA, Dittus RS, Allen DI, Freund DA.
Tricompartmental knee replacement. A comparison of orthopaedic surgeons' self
reported performance rates with surgical indications, contraindications, and
expected outcomes. Knee Replacement Patient Outcomes Research Team.
Clin Orthop Relat Res.1994;305:
209-17.305209
1994
[PubMed]
Marx RG, Jones EC, Angel M, Wickiewicz
TL, Warren RF. Beliefs and attitudes of members of the American Academy of
Orthopaedic Surgeons regarding the treatment of anterior cruciate ligament
injury. Arthroscopy.2003;19:
762-70.19762
2003
[PubMed][CrossRef]
Man-Son-Hing M, Molnar F, St. John P,
Brymer C, Rockwood K. Increasing physicians' response rates to mailed surveys:
effects of investigator's name recognition. Ann R Coll Phys Surg
Can.2000;33:
7-9.337
2000
Eddy DM. Clinical decision making: from
theory to practice. Designing a practice policy. Standards, guidelines, and
options. JAMA.1990;263:
3077, 3081, 3084.2633077
1990
[PubMed][CrossRef]
McConville OR, Iannotti JP.
Partial-thickness tears of the rotator cuff: evaluation and management.
J Am Acad Orthop Surg.1999;7:
32-43.732
1999
Earnshaw P, Desjardins D, Sarkar K,
Uhthoff HK. Rotator cuff tears: the role of surgery. Can J
Surg.1982;25:
60-3.2560
1982
Goldberg BA, Nowinski RJ, Matsen FA 3rd.
Outcome of nonoperative management of full-thickness rotator cuff tears.
Clin Orthop Relat Res.2001;382:
99-107.38299
2001
[PubMed][CrossRef]
Motycka T, Lehner A, Landsiedl F.
Comparison of débridement versus suture in large rotator cuff tears:
long-term study of 64 shoulders. Arch Orthop Trauma Surg.2004;124:
654-8.124654
2004
[PubMed][CrossRef]
Massoud SN, Levy O, Copeland SA.
Subacromial decompression. Treatment for small- and medium-sized tears of the
rotator cuff. J Bone Joint Surg Br.2002;84:
955-60.84955
2002
[PubMed][CrossRef]
Cordasco FA, Backer M, Craig EV, Klein
D, Warren RF. The partial-thickness rotator cuff tear: is acromioplasty
without repair sufficient? Am J Sports Med.2002;30:
257-60.30257
2002
[PubMed]
Melillo AS, Savoie FH 3rd, Field LD.
Massive rotator cuff tears: débridement versus repair. Orthop
Clin North Am.1997;28:
117-24.28117
1997
[CrossRef]
Rockwood CA Jr, Williams GR Jr, Burkhead
WZ Jr. Débridement of degenerative, irreparable lesions of the rotator
cuff. J Bone Joint Surg Am.1995;77:
857-66.77857
1995
[PubMed]
Weber SC. Arthroscopic
débridement and acromioplasty versus mini-open repair in the treatment
of significant partial-thickness rotator cuff tears.
Arthroscopy.1999;15:
126-31.15126
1999
[PubMed][CrossRef]
Severud EL, Ruotolo C, Abbott DD,
Nottage WM. All-arthroscopic versus mini-open rotator cuff repair: a long-term
retrospective outcome comparison. Arthroscopy.2003;19:
234-8.19234
2003
[PubMed][CrossRef]
Ogilvie-Harris DJ, Demaziere A.
Arthroscopic débridement versus open repair for rotator cuff tears. A
prospective cohort study. J Bone Joint Surg Br.1993;75:
416-20.75416
1993
[PubMed]
Jain N, Pietrobon R, Hocker S, Guller U,
Shankar A, Higgins LD. The relationship between surgeon and hospital volume
and outcomes for shoulder arthroplasty. J Bone Joint Surg Am.2004;86:
496-505.86496
2004
[PubMed]
Hammond JW, Queale WS, Kim TK, McFarland
EG. Surgeon experience and clinical and economic outcomes for shoulder
arthroplasty. J Bone Joint Surg Am.2003;85:
2318-24.852318
2003
[PubMed]
Norton EC, Garfinkel SA, McQuay LJ, Heck
DA, Wright JG, Dittus R, Lubitz RM. The effect of hospital volume on the
in-hospital complication rate in knee replacement patients. Health Serv
Res.1998;33:
1191-210.331191
1998
Lavernia CJ, Guzman JF. Relationship of
surgical volume to short-term mortality, morbidity, and hospital charges in
arthroplasty. J Arthroplasty.1995;10:
133-40.10133
1995
[PubMed][CrossRef]
Katz JN, Losina E, Barrett J, Phillips
CB, Mahomed NN, Lew RA, Guadagnoli E, Harris WH, Poss R, Baron JA. Association
between hospital and surgeon procedure volume and outcomes of total hip
replacement in the United States medicare population. J Bone Joint Surg
Am.2001;83:
1622-9.831622
2001
Luft HS, Hunt SS, Maerki SC. The
volume-outcome relationship: practice-makes-perfect or selective-referral
patterns? Health Serv Res.1987;22:
157-82.22157
1987
[PubMed]
Maerki SC, Luft HS, Hunt SS. Selecting
categories of patients for regionalization. Implications of the relationship
between volume and outcome. Med Care.1986;24:
148-58.24148
1986
[PubMed][CrossRef]
Lasserre V, Guihenneuc-Jouyaux C,
Richardson S. Biases in ecological studies: utility of including within-area
distribution of confounders. Stat Med.2000;19:
45-59.1945
2000
[PubMed][CrossRef]
Wen SW, Demissie K, August D, Rhoads GG.
Level of aggregation for optimal epidemiological analysis: the case of time to
surgery and unnecessary removal of the normal appendix. J Epidemiol
Community Health.2001;55:
198-203.55198
2001
[CrossRef]