Subscapularis and Capsular Release
The operation is performed with the patient under general anesthesia and in
the beach-chair position (Fig.
1). A deltopectoral approach that emphasizes preservation of the
entire deltoid origin and insertion is used
(Figs. 2-A and 2-B). Once the
incision has been made, the cephalic vein is identified and mobilized
laterally with the deltoid muscle.
The subscapularis is detached from its insertion on the lesser tuberosity
and is elevated separately from the underlying anterior aspect of the capsule.
In order to maximize its length, the subscapularis tendon is detached from the
lesser tuberosity in its entirety rather than through its tendinous portion
(Fig. 3). Adhesions from the
base of the coracoid process are released, and the entire anterior aspect of
the capsule is excised. These releases are performed in order to free the
subscapularis muscle-tendon unit circumferentially for 360° about its long
axis (Figs. 4-A and 4-B).
Subscapularis reattachment is accomplished with use of 1-mm Cottony Dacron
sutures (Deknatel, Fall River, Massachusetts) passed through 2-cm-long bone
tunnels from the neck of the humerus to the osteotomy site
(Figs. 5-A, 5-B, and 5-C). At
the conclusion of the arthroplasty, the subscapularis tendon is reattached in
a more medial location at the proximal humeral osteotomy site, thereby
functionally lengthening the muscle-tendon unit by 1 to 2 cm
(Fig. 6).
Resection of the Humeral Head
The articular surface of the humeral head is resected in a plane just
inside the rotator cuff insertion at the level of the greater tuberosity. The
humeral osteotomy ranges between 20° and 30° of retroversion. The
location of the varus-valgus angle of humeral head resection is determined by
placing a humeral osteotomy template along the anterior aspect of the arm
parallel to the shaft of the humerus (Fig.
7). The superior lateral portion of the mark is located at the
junction of the articular surface with the attachment of the rotator cuff on
the greater tuberosity.
A glenoid that is nonconcentric and/or demonstrates moderate-to-severe bone
loss is reamed with a power reamer to normalize glenoid version with respect
to the scapula and to provide a concentric glenoid articular surface
(Figs. 8-A and 8-B). Reamers
are available in five different sizes, and the selection is based on a set of
trial glenoid components used for total shoulder arthroplasty
(Figs. 9-A, 9-B, and 9-C).
Orientation of the reamer is facilitated by palpating the lateral extent of
the subscapularis fossa at a point midway between the superior and lateral
borders of the scapula. This point is described as the "centering
point"1
(Fig. 10). A line connecting
this point to the center of the glenoid face is the normalized glenoid center
line. Orienting the reamer to the normalized glenoid center line enables the
surgeon to both contour the glenoid into a concentric articulating surface and
correct pathologic glenoid version (Figs.
11-A and 11-B).
CRITICAL CONCEPTSINDICATIONS:The indication for prosthetic hemiarthroplasty is a limitation in the
activities of daily living caused by glenohumeral arthrosis combined with
shoulder pain refractory to nonoperative treatment in a cooperative,
motivated, and sufficiently healthy
patient2-4.
Hemiarthroplasty can be used to reconstruct the arthritic shoulder when the
following conditions are met:A concentric glenoid consisting of eburnated boneA nonconcentric glenoid that can be converted to a smooth concentric
surface by
reaming5The humeral head is centered in the glenoid preoperatively or at the time
of surgery by means of soft-tissue balancing and glenoid preparation
(Figs. 16-A and 16-B)The surgeon is proficient with the techniques required to gain optimal
exposure of the glenohumeral joint, release capsular contractures, address
eccentric glenoid wear, and assess soft-tissue balancingCONTRAINDICATIONS:Remote infection, previous shoulder surgery, alcoholism, smoking, narcotic
use, substantial Parkinson disease, neuropathic arthritis, and crutch
dependency are known to lessen the chances of a good result. Contraindications
to hemiarthroplasty include:A cystic or pitted osteopenic glenoidA nonconcentric glenoid not correctable by reamingModerate or severe glenohumeral subluxation that persists following glenoid
preparation and attempts at soft-tissue balancingActive or recent infectionAbsent deltoid functionPoor general health and an inability or unwillingness to cooperate with a
physician-directed rehabilitation programPITFALLS:Preoperative planning is paramount to the success of this procedure. Use of
standardized radiographs and implant templates helps to establish the proper
position of the humeral implant and to alert the surgeon to possible problems
(Fig. 17). Additionally,
computed tomography is quite helpful for evaluating substantial glenoid
erosion and increased glenoid retroversion
(Fig. 18).The technique of prosthetic replacement of the humeral head requires great
familiarity with the anatomy and biomechanics of the shoulder. Critical to the
final outcome of this procedure is maintenance of the deltoid origin and
insertion because loss of the deltoid through a failed repair or injury to the
axillary nerve results in a catastrophic loss of shoulder function.The locations of the axillary and musculocutaneous nerves must always be
evident to the surgeon and are of paramount importance. Although positioning
the arm in adduction and external rotation may make anterior approaches to the
glenohumeral joint safer, it is much better to identify the nerves and protect
them throughout the entire surgical procedure
(Figs. 19-A and 19-B). Nassar
et al. described in detail the tremendous variation, from one shoulder to
another, in the course and position of the axillary
nerve6.Intraoperative fractures are usually the result of inadvertent reaming,
overzealous impaction, or manipulation of the upper extremity during glenoid
exposure. In the latter case, humeral fractures can usually be avoided by
thorough capsular release, gentle external rotation, and extension of the
upper
extremity7.An osteotomy of the humeral head that is too lateral or in excessive
retroversion will compromise the rotator cuff insertion. Protection of the
cuff during resection is accomplished by placing a large curved Crego
retractor just inside the rotator cuff insertion posteriorly
(Fig. 20).Failure to resect marginal osteophytes about the proximal part of the
humerus predisposes to symptomatic abutment with the glenoid and coracoid as
well as to impaired motion.Overzealous reaming removes an excessive amount of bone from the glenoid
fossa, which decreases the glenoid articular surface area and diminishes the
supporting subchondral bone. In this setting, the net humeral joint reaction
force is concentrated on a smaller articular surface and the effective glenoid
arc is diminished, which may lead to glenohumeral subluxation or
dislocation.A nonconcentric glenoid may be converted to a smooth concentric surface by
reaming, but failure to orient the reamer along the normalized glenoid center
line will not correct the glenoid orientation in the case of abnormal
retroversion. In this scenario, the glenoid center line is divergent from the
net humeral joint reaction force, increasing the propensity for posterior
glenohumeral subluxation (Fig.
21).Malposition of the humeral component is often overlooked as a cause of
shoulder stiffness. A component placed low and in varus will result in a tight
shoulder when the arm is in the adducted position; in contrast, a humeral
component that is too high results in tightening of the inferior aspect of the
capsule during elevation (Fig.
22).Replacing the resected humeral head with a larger, nonanatomic component
results in an "overstuffed" shoulder. This decreases normal joint
laxity and contributes to shoulder stiffness. A stiff shoulder secondary to an
oversized humeral head component not only has a limited range of motion but
also may compromise the rotator cuff and lead to obligate translation at the
extremes of motion (Fig.
23).Failures to inspect the subscapularis fossa, the subcoracoid recess, the
posterior axillary recess, and the bicipital groove for loose bodies are
pitfalls.Subscapularis and anterior capsular contractures are common in patients
with glenohumeral arthrosis, and release of these structures is a key step in
reconstructing the arthritic shoulder. However, some of these shoulders have
moderate-to-severeposterior glenohumeral subluxation preoperatively. The
posterior aspect of the capsule in this setting is stretched and should not be
released because doing so increases the propensity for recurrent posterior
shoulder instability postoperatively.Subscapularis failure and subsequent anterior glenohumeral instability may
result from thin, fragile tissue, which is especially susceptible to injury
during the first four to six postoperative weeks. Repairing the subscapularis
to the osteotomy site with nonabsorbable 1-mm Dacron tape through 2-cm-long
tunnels created in the anterior aspect of the humeral neck
(Figs. 5-A, 5-B, and 5-C) and
physician-directed postoperative rehabilitation decrease the likelihood of
this complication.
CRITICAL CONCEPTS
INDICATIONS:
The indication for prosthetic hemiarthroplasty is a limitation in the
activities of daily living caused by glenohumeral arthrosis combined with
shoulder pain refractory to nonoperative treatment in a cooperative,
motivated, and sufficiently healthy
patient2-4.
Hemiarthroplasty can be used to reconstruct the arthritic shoulder when the
following conditions are met:
A concentric glenoid consisting of eburnated boneA nonconcentric glenoid that can be converted to a smooth concentric
surface by
reaming5The humeral head is centered in the glenoid preoperatively or at the time
of surgery by means of soft-tissue balancing and glenoid preparation
(Figs. 16-A and 16-B)The surgeon is proficient with the techniques required to gain optimal
exposure of the glenohumeral joint, release capsular contractures, address
eccentric glenoid wear, and assess soft-tissue balancing
A concentric glenoid consisting of eburnated bone
A nonconcentric glenoid that can be converted to a smooth concentric
surface by
reaming5
The humeral head is centered in the glenoid preoperatively or at the time
of surgery by means of soft-tissue balancing and glenoid preparation
(Figs. 16-A and 16-B)
The surgeon is proficient with the techniques required to gain optimal
exposure of the glenohumeral joint, release capsular contractures, address
eccentric glenoid wear, and assess soft-tissue balancing
CONTRAINDICATIONS:
Remote infection, previous shoulder surgery, alcoholism, smoking, narcotic
use, substantial Parkinson disease, neuropathic arthritis, and crutch
dependency are known to lessen the chances of a good result. Contraindications
to hemiarthroplasty include:
A cystic or pitted osteopenic glenoidA nonconcentric glenoid not correctable by reamingModerate or severe glenohumeral subluxation that persists following glenoid
preparation and attempts at soft-tissue balancingActive or recent infectionAbsent deltoid functionPoor general health and an inability or unwillingness to cooperate with a
physician-directed rehabilitation program
A cystic or pitted osteopenic glenoid
A nonconcentric glenoid not correctable by reaming
Moderate or severe glenohumeral subluxation that persists following glenoid
preparation and attempts at soft-tissue balancing
Active or recent infection
Absent deltoid function
Poor general health and an inability or unwillingness to cooperate with a
physician-directed rehabilitation program
PITFALLS:
Preoperative planning is paramount to the success of this procedure. Use of
standardized radiographs and implant templates helps to establish the proper
position of the humeral implant and to alert the surgeon to possible problems
(Fig. 17). Additionally,
computed tomography is quite helpful for evaluating substantial glenoid
erosion and increased glenoid retroversion
(Fig. 18).The technique of prosthetic replacement of the humeral head requires great
familiarity with the anatomy and biomechanics of the shoulder. Critical to the
final outcome of this procedure is maintenance of the deltoid origin and
insertion because loss of the deltoid through a failed repair or injury to the
axillary nerve results in a catastrophic loss of shoulder function.The locations of the axillary and musculocutaneous nerves must always be
evident to the surgeon and are of paramount importance. Although positioning
the arm in adduction and external rotation may make anterior approaches to the
glenohumeral joint safer, it is much better to identify the nerves and protect
them throughout the entire surgical procedure
(Figs. 19-A and 19-B). Nassar
et al. described in detail the tremendous variation, from one shoulder to
another, in the course and position of the axillary
nerve6.Intraoperative fractures are usually the result of inadvertent reaming,
overzealous impaction, or manipulation of the upper extremity during glenoid
exposure. In the latter case, humeral fractures can usually be avoided by
thorough capsular release, gentle external rotation, and extension of the
upper
extremity7.An osteotomy of the humeral head that is too lateral or in excessive
retroversion will compromise the rotator cuff insertion. Protection of the
cuff during resection is accomplished by placing a large curved Crego
retractor just inside the rotator cuff insertion posteriorly
(Fig. 20).Failure to resect marginal osteophytes about the proximal part of the
humerus predisposes to symptomatic abutment with the glenoid and coracoid as
well as to impaired motion.Overzealous reaming removes an excessive amount of bone from the glenoid
fossa, which decreases the glenoid articular surface area and diminishes the
supporting subchondral bone. In this setting, the net humeral joint reaction
force is concentrated on a smaller articular surface and the effective glenoid
arc is diminished, which may lead to glenohumeral subluxation or
dislocation.A nonconcentric glenoid may be converted to a smooth concentric surface by
reaming, but failure to orient the reamer along the normalized glenoid center
line will not correct the glenoid orientation in the case of abnormal
retroversion. In this scenario, the glenoid center line is divergent from the
net humeral joint reaction force, increasing the propensity for posterior
glenohumeral subluxation (Fig.
21).Malposition of the humeral component is often overlooked as a cause of
shoulder stiffness. A component placed low and in varus will result in a tight
shoulder when the arm is in the adducted position; in contrast, a humeral
component that is too high results in tightening of the inferior aspect of the
capsule during elevation (Fig.
22).Replacing the resected humeral head with a larger, nonanatomic component
results in an "overstuffed" shoulder. This decreases normal joint
laxity and contributes to shoulder stiffness. A stiff shoulder secondary to an
oversized humeral head component not only has a limited range of motion but
also may compromise the rotator cuff and lead to obligate translation at the
extremes of motion (Fig.
23).Failures to inspect the subscapularis fossa, the subcoracoid recess, the
posterior axillary recess, and the bicipital groove for loose bodies are
pitfalls.Subscapularis and anterior capsular contractures are common in patients
with glenohumeral arthrosis, and release of these structures is a key step in
reconstructing the arthritic shoulder. However, some of these shoulders have
moderate-to-severeposterior glenohumeral subluxation preoperatively. The
posterior aspect of the capsule in this setting is stretched and should not be
released because doing so increases the propensity for recurrent posterior
shoulder instability postoperatively.Subscapularis failure and subsequent anterior glenohumeral instability may
result from thin, fragile tissue, which is especially susceptible to injury
during the first four to six postoperative weeks. Repairing the subscapularis
to the osteotomy site with nonabsorbable 1-mm Dacron tape through 2-cm-long
tunnels created in the anterior aspect of the humeral neck
(Figs. 5-A, 5-B, and 5-C) and
physician-directed postoperative rehabilitation decrease the likelihood of
this complication.
Preoperative planning is paramount to the success of this procedure. Use of
standardized radiographs and implant templates helps to establish the proper
position of the humeral implant and to alert the surgeon to possible problems
(Fig. 17). Additionally,
computed tomography is quite helpful for evaluating substantial glenoid
erosion and increased glenoid retroversion
(Fig. 18).
The technique of prosthetic replacement of the humeral head requires great
familiarity with the anatomy and biomechanics of the shoulder. Critical to the
final outcome of this procedure is maintenance of the deltoid origin and
insertion because loss of the deltoid through a failed repair or injury to the
axillary nerve results in a catastrophic loss of shoulder function.
The locations of the axillary and musculocutaneous nerves must always be
evident to the surgeon and are of paramount importance. Although positioning
the arm in adduction and external rotation may make anterior approaches to the
glenohumeral joint safer, it is much better to identify the nerves and protect
them throughout the entire surgical procedure
(Figs. 19-A and 19-B). Nassar
et al. described in detail the tremendous variation, from one shoulder to
another, in the course and position of the axillary
nerve6.
Intraoperative fractures are usually the result of inadvertent reaming,
overzealous impaction, or manipulation of the upper extremity during glenoid
exposure. In the latter case, humeral fractures can usually be avoided by
thorough capsular release, gentle external rotation, and extension of the
upper
extremity7.
An osteotomy of the humeral head that is too lateral or in excessive
retroversion will compromise the rotator cuff insertion. Protection of the
cuff during resection is accomplished by placing a large curved Crego
retractor just inside the rotator cuff insertion posteriorly
(Fig. 20).
Failure to resect marginal osteophytes about the proximal part of the
humerus predisposes to symptomatic abutment with the glenoid and coracoid as
well as to impaired motion.
Overzealous reaming removes an excessive amount of bone from the glenoid
fossa, which decreases the glenoid articular surface area and diminishes the
supporting subchondral bone. In this setting, the net humeral joint reaction
force is concentrated on a smaller articular surface and the effective glenoid
arc is diminished, which may lead to glenohumeral subluxation or
dislocation.
A nonconcentric glenoid may be converted to a smooth concentric surface by
reaming, but failure to orient the reamer along the normalized glenoid center
line will not correct the glenoid orientation in the case of abnormal
retroversion. In this scenario, the glenoid center line is divergent from the
net humeral joint reaction force, increasing the propensity for posterior
glenohumeral subluxation (Fig.
21).
Malposition of the humeral component is often overlooked as a cause of
shoulder stiffness. A component placed low and in varus will result in a tight
shoulder when the arm is in the adducted position; in contrast, a humeral
component that is too high results in tightening of the inferior aspect of the
capsule during elevation (Fig.
22).
Replacing the resected humeral head with a larger, nonanatomic component
results in an "overstuffed" shoulder. This decreases normal joint
laxity and contributes to shoulder stiffness. A stiff shoulder secondary to an
oversized humeral head component not only has a limited range of motion but
also may compromise the rotator cuff and lead to obligate translation at the
extremes of motion (Fig.
23).
Failures to inspect the subscapularis fossa, the subcoracoid recess, the
posterior axillary recess, and the bicipital groove for loose bodies are
pitfalls.
Subscapularis and anterior capsular contractures are common in patients
with glenohumeral arthrosis, and release of these structures is a key step in
reconstructing the arthritic shoulder. However, some of these shoulders have
moderate-to-severeposterior glenohumeral subluxation preoperatively. The
posterior aspect of the capsule in this setting is stretched and should not be
released because doing so increases the propensity for recurrent posterior
shoulder instability postoperatively.
Subscapularis failure and subsequent anterior glenohumeral instability may
result from thin, fragile tissue, which is especially susceptible to injury
during the first four to six postoperative weeks. Repairing the subscapularis
to the osteotomy site with nonabsorbable 1-mm Dacron tape through 2-cm-long
tunnels created in the anterior aspect of the humeral neck
(Figs. 5-A, 5-B, and 5-C) and
physician-directed postoperative rehabilitation decrease the likelihood of
this complication.
Assessment of Soft-Tissue Balancing and Closure
Periarticular osteophytes are removed from both sides of the shoulder
joint, and an anatomically sized modular humeral component (DePuy, a Johnson
and Johnson company, Warsaw, Indiana) is seated in place
(Fig. 12). Soft-tissue
balancing is judged to be optimal when (1) posterior drawer testing
demonstrates 40% to 60% posterior translation of the humeral head relative to
the center of the glenoid (Fig.
13), (2) when there is 75° of internal rotation with the arm
positioned in 90° of abduction (Fig.
14), (3) when the hand on the surgically treated side can be
placed on the superior aspect of the contralateral shoulder without
protraction of the scapula (Fig.
15), and (4) when there is 45° of external rotation with the
subscapularis approximated to the proximal humeral osteotomy site.
Postoperative Protocol
All patients participate in a physician-directed postoperative
rehabilitation program. On the afternoon of the day of the surgery, the
physician performs passive forward flexion of the patient's arm up to 90°,
or as far as is comfortable for the patient. On the first postoperative day,
the patient performs passive forward flexion with a pulley attached to an
overhead frame, passive external rotation within a comfortable range with use
of a meter stick, and pendulum exercises. Each exercise involves five
repetitions and is performed three or four times a day, seven days a week. The
patient is encouraged to use the arm for gentle activities of daily living and
is usually discharged on the second postoperative day.
AUTHOR UPDATE:The patient selection strategy, surgical technique, and principles guiding
assessment of soft-tissue balancing are similar to those employed in the
originally reported series. However, a few changes have been made to the
surgical technique, and a modification of the reamers is in process. These
changes include:Degenerative changes of the long head of the biceps tendon are routinely
managed by tenodesis within the bicipital groove of the humerus and excision
of the intra-articular segment of the tendon.To decrease the possibility of postoperative subscapularis rupture, which
occurred in two of the forty-three patients in the original series, one of us
(M.A.W.) incises the subscapularis tendon at its insertion to the lesser
tuberosity along with the anterior aspect of the capsule. This method of
detachment provides a thicker and more robust structure for reattachment to
the humeral osteotomy site.The nonprosthetic glenoid arthroplasty employed in the original series can
restore smoothness and orientation of the glenoid surface by means of
spherical reaming. While five different sizes of glenoid reamers were
available, they were not specifically matched in convexity to the prosthetic
humeral head, which may be a disadvantage in nonprosthetic glenoid
arthroplasty5. As a
result, a modification of the reamers that would provide a nearly matched
convexity between an individual reamer and a corresponding prosthetic humeral
head is pending.
AUTHOR UPDATE:
The patient selection strategy, surgical technique, and principles guiding
assessment of soft-tissue balancing are similar to those employed in the
originally reported series. However, a few changes have been made to the
surgical technique, and a modification of the reamers is in process. These
changes include:
Degenerative changes of the long head of the biceps tendon are routinely
managed by tenodesis within the bicipital groove of the humerus and excision
of the intra-articular segment of the tendon.To decrease the possibility of postoperative subscapularis rupture, which
occurred in two of the forty-three patients in the original series, one of us
(M.A.W.) incises the subscapularis tendon at its insertion to the lesser
tuberosity along with the anterior aspect of the capsule. This method of
detachment provides a thicker and more robust structure for reattachment to
the humeral osteotomy site.The nonprosthetic glenoid arthroplasty employed in the original series can
restore smoothness and orientation of the glenoid surface by means of
spherical reaming. While five different sizes of glenoid reamers were
available, they were not specifically matched in convexity to the prosthetic
humeral head, which may be a disadvantage in nonprosthetic glenoid
arthroplasty5. As a
result, a modification of the reamers that would provide a nearly matched
convexity between an individual reamer and a corresponding prosthetic humeral
head is pending.
Degenerative changes of the long head of the biceps tendon are routinely
managed by tenodesis within the bicipital groove of the humerus and excision
of the intra-articular segment of the tendon.
To decrease the possibility of postoperative subscapularis rupture, which
occurred in two of the forty-three patients in the original series, one of us
(M.A.W.) incises the subscapularis tendon at its insertion to the lesser
tuberosity along with the anterior aspect of the capsule. This method of
detachment provides a thicker and more robust structure for reattachment to
the humeral osteotomy site.
The nonprosthetic glenoid arthroplasty employed in the original series can
restore smoothness and orientation of the glenoid surface by means of
spherical reaming. While five different sizes of glenoid reamers were
available, they were not specifically matched in convexity to the prosthetic
humeral head, which may be a disadvantage in nonprosthetic glenoid
arthroplasty5. As a
result, a modification of the reamers that would provide a nearly matched
convexity between an individual reamer and a corresponding prosthetic humeral
head is pending.