The patient is placed in a lateral decubitus position. Correct lateral
positioning helps for intraoperative assessment of the acetabular version. The
patient is stabilized with three or four side stilts that do not interfere
with the operative field. The posterior holder should be placed close to the
buttock, and the anterior one should be placed adjacent and slightly cephalad
to the pubic symphysis. The uninvolved lower limb is placed in a tunnel
bolster to avoid pressure sores and to have a flat bearing for the involved
lower limb (Fig. 1).
Disinfection includes the entire lower extremity and is extended up to the
lowest rib. This is followed by draping the lower extremity mobile, starting
from the iliac crest and ending at the middle part of the thigh. A sterile bag
is placed anteriorly at the level of the knee for later positioning of the
lower extremity during dislocation of the hip. Both the anterior superior
iliac spine and the posterior superior iliac spine should be freely palpable.
A Gibson approach is favored, which differs from the Kocher-Langenbeck
approach in that the anterior muscle fibers of the gluteus maximus are not
split and, as a result, the neurovascular supply is not at
risk6,7.
The gluteus maximus muscle receives its neurovascular supply from branches of
the inferior gluteal artery and nerve, and splitting of the muscle comes close
to these neurovascular structures. Cautery of bleeders might cause
simultaneous damage to the terminal branches of the inferior gluteal nerve.
The approach allows almost unrestricted access to the posterior column. The
length of the straight skin incision averages 20 cm but depends on patient
size and body mass index. In its longitudinal course, it is centered over the
tip of the greater trochanter and runs through the anterior one-third of the
greater trochanter. Using an excessively short incision might be dangerous,
causing soft-tissue damage to the skin and musculature as a result of
stretching.
CRITICAL CONCEPTSINDICATIONS:A patient who presents with a history of pain in the groin, especially
during combined flexion and internal rotation of the hip, should be suspected
of having femoro-acetabular impingement, particularly if the clinical
evaluation reveals limited internal rotation during hip flexion and a positive
anterior impingement test. When there is radiographic evidence of
abnormalities such as asphericity of the femoral head, acetabular overcoverage
(local or global), and even secondary cartilaginous lesions as evidenced by
magnetic resonance imaging, surgical treatment should be considered.
Femoro-acetabular impingement itself can be caused by (1) localized or
generalized acetabular overcoverage (retroversion or coxa profunda), (2) a
nonspherical femoral head, (3) an insufficiently narrowed head-neck junction,
(4) pelvic osteotomies that result in overcorrection, and (5) combined
extra-articular and intraarticular impingement. Good indications are clearly
detectable morphological abnormalities in the absence of advanced secondary
changes to the cartilage. Frequently, a diagnostic injection is helpful for
determining the intraarticular origin of hip pain.CONTRAINDICATIONS:In cases of advanced osteoarthritis, open treatment of femoro-acetabular
impingement is certainly not warranted. In such patients, either hip
arthroplasty or other measures should be used while taking into account
patient age, activity level, and expectations. However, even slight
joint-space narrowing, if it is indicative of substantial cartilage damage
causing pathological axial loading, will limit expectations for a good
outcome. Acetabular rim lesions in the absence of clearly detectable
acetabular or femoral pathology should also be apprehended with caution
because extra-articular causes such as hyperlaxity cannot be sufficiently
addressed with open surgery.PITFALLS:Blood Supply to Femoral HeadA thorough knowledge of the blood supply in the adult hip is mandatory to
allow safe execution of surgical dislocation of the hip. The medial femoral
circumflex artery is the primary source of blood flow to the adult femoral
head; it arises from the deep femoral artery. The medial femoral circumflex
artery courses posteriorly between the psoas and pectineus muscles before
approaching the posterior aspect of the proximal part of the femur, running
along the inferior border of the obturator externus muscle and just proximal
to the quadratus femoris. A constant trochanteric branch separates at the
level of the external obturator tendon and curves anteriorly over the greater
trochanter. This vessel can be used to locate the deep branch of the medial
femoral circumflex artery, the superior border of the quadratus femoris, and
the tendon of the obturator externus. The deep branch of the medial femoral
circumflex artery crosses the tendon of the obturator externus posteriorly and
continues anterior to the conjoined tendon, which consists of the superior and
inferior gemellus and the obturator internus tendon. Its course explains why
the short external rotators must be protected. It perforates the capsule at
the superior margin of the superior gemellus tendon and divides into several
terminal branches, the so-called retinacular vessels. Almost 80% of all
foramina are located at the posterosuperior head-neck
junction10. A
mobile wad of loose connective and synovial tissue covers these vessels and is
referred to as the retinaculum. During dislocation of the femoral head, the
external rotators, especially the obturator externus, protects the medial
femoral circumflex artery from stretching or rupture. If the capsulotomy is
performed strictly anteriorly, damage to the retinaculum can be avoided.Nerve InjuryThe sciatic nerve runs in close proximity to the piriformis muscle and is
at risk when the capsular exposure is erroneously performed distal to the
piriformis muscle. This is even more dangerous in the rare case of a
double-branched sciatic nerve that encloses the piriformis. Under such
circumstances, the insertion of the piriformis tendon at the greater
trochanter should be released to avoid stretching the branches during
dislocation. In patients who have had previous hip surgery, the sciatic nerve
may be entrapped within scar tissue. This again places the nerve at higher
risk for traction injury during dislocation. In such a condition, the nerve is
preferably identified and is released from any scar tissue before the
procedure proceeds.ApproachesThe straight lateral incision is preferred in the obese or female patient
to avoid development of a saddlebag deformity. A longer incision may
facilitate surgical exposure of the hip, helps to protect the muscle fibers,
and allows for easy dislocation of the femoral head with an unlimited view.
The Kocher-Langenbeck approach has one advantage over the Gibson approach: it
allows better inspection of the posterior aspect of the femoral head and neck,
especially in obese patients.PITFALLS:Trochanteric OsteotomyThere is a high risk of osteonecrosis of the femoral head if the osteotomy
is too medial and extends into the base of the neck. Therefore, the
posterosuperior edge of the greater trochanter should be identified before the
trochanteric osteotomy is performed, and it is of paramount importance that
the osteotomy exits anterior to the posterosuperior edge of the greater
trochanter. The fragment should be adequately sized (optimal thickness, 15 mm)
to allow stable reattachment to the trochanteric base. A trochanteric fragment
that is too thin may fracture and avulse.CapsulotomyTo reduce the risk of iatrogenic lesions of the femoral head cartilage
and/or acetabular labrum, the lower extremity should be brought into flexion
and external rotation during capsulotomy. After a short incision near the base
of the anterior aspect of the neck, the remaining cuts should be performed
with an inside-out technique. The longitudinal limb of the capsulotomy follows
the course of the femoral neck slightly anterior to the iliofemoral ligament.
The inferomedial incision of the capsule must be stopped anterior to the
lesser trochanter to avoid injury to the origin of the medial femoral
circumflex artery. The transverse limb is performed by incising the capsule
along the superior acetabular rim until the piriformis tendon is reached.
Doing so allows the limb to stay sufficiently (approximately 3 cm) proximal to
the capsular perforation of the medial femoral circumflex artery.
Additionally, care has to be taken not to damage the underlying labrum.Dislocation of the HipCutting the ligamentum capitis femoris does not compromise the blood supply
to the adult femoral head but enhances exposure of the acetabulum and the
femoral head. Cartilage is very susceptible to damage caused by dehydration.
Thus, continuous irrigation of the cartilaginous surface is required.Acetabular CorrectionThe surgeon must avoid excessive resection of the acetabular rim because
this may lead to undercoverage of the femoral head, which in turn may result
in a tendency for superolateral migration and instability of the femoral
head.Restoring the Contour of the Femoral Head-Neck JunctionThe safe zone in which to perform osteochondroplasty is anterior and
anterolateral. If the resection has to be extended more laterally, it is
absolutely necessary to stay proximal to the retinacular vessels with the
osteochondroplasty in order to avoid creating osteonecrosis of the femoral
head. Excessive osseous resection at the head-neck junction (>30%)
mechanically weakens the femoral neck.AUTHOR UPDATE:For the past few years, we have preferred the straight Gibson-type approach
over the Kocher-Langenbeck approach. The former approach better preserves the
gluteus maximus (muscle fibers and neurovascular structures) while still
providing adequate exposure of the hip joint. Additionally, it has an
advantage over the Kocher-Langenbeck approach especially when used for the
treatment of obese female patients, who have a higher risk for the development
of a saddlebag deformity. Prior to June 2001, we resected the labrum.
Thereafter, we started to refix the intact labral portion back to the osseous
acetabular rim whenever possible. As we have reported, the results of labral
refixation have been
promising9;
resection of the labrum is warranted only if there is no intact labrum
remaining. Postoperative continuous passive motion has been successful for
reducing the small but real risk of intracapsular adhesions.
CRITICAL CONCEPTS
INDICATIONS:
A patient who presents with a history of pain in the groin, especially
during combined flexion and internal rotation of the hip, should be suspected
of having femoro-acetabular impingement, particularly if the clinical
evaluation reveals limited internal rotation during hip flexion and a positive
anterior impingement test. When there is radiographic evidence of
abnormalities such as asphericity of the femoral head, acetabular overcoverage
(local or global), and even secondary cartilaginous lesions as evidenced by
magnetic resonance imaging, surgical treatment should be considered.
Femoro-acetabular impingement itself can be caused by (1) localized or
generalized acetabular overcoverage (retroversion or coxa profunda), (2) a
nonspherical femoral head, (3) an insufficiently narrowed head-neck junction,
(4) pelvic osteotomies that result in overcorrection, and (5) combined
extra-articular and intraarticular impingement. Good indications are clearly
detectable morphological abnormalities in the absence of advanced secondary
changes to the cartilage. Frequently, a diagnostic injection is helpful for
determining the intraarticular origin of hip pain.
CONTRAINDICATIONS:
In cases of advanced osteoarthritis, open treatment of femoro-acetabular
impingement is certainly not warranted. In such patients, either hip
arthroplasty or other measures should be used while taking into account
patient age, activity level, and expectations. However, even slight
joint-space narrowing, if it is indicative of substantial cartilage damage
causing pathological axial loading, will limit expectations for a good
outcome. Acetabular rim lesions in the absence of clearly detectable
acetabular or femoral pathology should also be apprehended with caution
because extra-articular causes such as hyperlaxity cannot be sufficiently
addressed with open surgery.
PITFALLS:
Blood Supply to Femoral Head
A thorough knowledge of the blood supply in the adult hip is mandatory to
allow safe execution of surgical dislocation of the hip. The medial femoral
circumflex artery is the primary source of blood flow to the adult femoral
head; it arises from the deep femoral artery. The medial femoral circumflex
artery courses posteriorly between the psoas and pectineus muscles before
approaching the posterior aspect of the proximal part of the femur, running
along the inferior border of the obturator externus muscle and just proximal
to the quadratus femoris. A constant trochanteric branch separates at the
level of the external obturator tendon and curves anteriorly over the greater
trochanter. This vessel can be used to locate the deep branch of the medial
femoral circumflex artery, the superior border of the quadratus femoris, and
the tendon of the obturator externus. The deep branch of the medial femoral
circumflex artery crosses the tendon of the obturator externus posteriorly and
continues anterior to the conjoined tendon, which consists of the superior and
inferior gemellus and the obturator internus tendon. Its course explains why
the short external rotators must be protected. It perforates the capsule at
the superior margin of the superior gemellus tendon and divides into several
terminal branches, the so-called retinacular vessels. Almost 80% of all
foramina are located at the posterosuperior head-neck
junction10. A
mobile wad of loose connective and synovial tissue covers these vessels and is
referred to as the retinaculum. During dislocation of the femoral head, the
external rotators, especially the obturator externus, protects the medial
femoral circumflex artery from stretching or rupture. If the capsulotomy is
performed strictly anteriorly, damage to the retinaculum can be avoided.
Nerve Injury
The sciatic nerve runs in close proximity to the piriformis muscle and is
at risk when the capsular exposure is erroneously performed distal to the
piriformis muscle. This is even more dangerous in the rare case of a
double-branched sciatic nerve that encloses the piriformis. Under such
circumstances, the insertion of the piriformis tendon at the greater
trochanter should be released to avoid stretching the branches during
dislocation. In patients who have had previous hip surgery, the sciatic nerve
may be entrapped within scar tissue. This again places the nerve at higher
risk for traction injury during dislocation. In such a condition, the nerve is
preferably identified and is released from any scar tissue before the
procedure proceeds.
Approaches
The straight lateral incision is preferred in the obese or female patient
to avoid development of a saddlebag deformity. A longer incision may
facilitate surgical exposure of the hip, helps to protect the muscle fibers,
and allows for easy dislocation of the femoral head with an unlimited view.
The Kocher-Langenbeck approach has one advantage over the Gibson approach: it
allows better inspection of the posterior aspect of the femoral head and neck,
especially in obese patients.
PITFALLS:
Trochanteric Osteotomy
There is a high risk of osteonecrosis of the femoral head if the osteotomy
is too medial and extends into the base of the neck. Therefore, the
posterosuperior edge of the greater trochanter should be identified before the
trochanteric osteotomy is performed, and it is of paramount importance that
the osteotomy exits anterior to the posterosuperior edge of the greater
trochanter. The fragment should be adequately sized (optimal thickness, 15 mm)
to allow stable reattachment to the trochanteric base. A trochanteric fragment
that is too thin may fracture and avulse.
Capsulotomy
To reduce the risk of iatrogenic lesions of the femoral head cartilage
and/or acetabular labrum, the lower extremity should be brought into flexion
and external rotation during capsulotomy. After a short incision near the base
of the anterior aspect of the neck, the remaining cuts should be performed
with an inside-out technique. The longitudinal limb of the capsulotomy follows
the course of the femoral neck slightly anterior to the iliofemoral ligament.
The inferomedial incision of the capsule must be stopped anterior to the
lesser trochanter to avoid injury to the origin of the medial femoral
circumflex artery. The transverse limb is performed by incising the capsule
along the superior acetabular rim until the piriformis tendon is reached.
Doing so allows the limb to stay sufficiently (approximately 3 cm) proximal to
the capsular perforation of the medial femoral circumflex artery.
Additionally, care has to be taken not to damage the underlying labrum.
Dislocation of the Hip
Cutting the ligamentum capitis femoris does not compromise the blood supply
to the adult femoral head but enhances exposure of the acetabulum and the
femoral head. Cartilage is very susceptible to damage caused by dehydration.
Thus, continuous irrigation of the cartilaginous surface is required.
Acetabular Correction
The surgeon must avoid excessive resection of the acetabular rim because
this may lead to undercoverage of the femoral head, which in turn may result
in a tendency for superolateral migration and instability of the femoral
head.
Restoring the Contour of the Femoral Head-Neck Junction
The safe zone in which to perform osteochondroplasty is anterior and
anterolateral. If the resection has to be extended more laterally, it is
absolutely necessary to stay proximal to the retinacular vessels with the
osteochondroplasty in order to avoid creating osteonecrosis of the femoral
head. Excessive osseous resection at the head-neck junction (>30%)
mechanically weakens the femoral neck.
AUTHOR UPDATE:
For the past few years, we have preferred the straight Gibson-type approach
over the Kocher-Langenbeck approach. The former approach better preserves the
gluteus maximus (muscle fibers and neurovascular structures) while still
providing adequate exposure of the hip joint. Additionally, it has an
advantage over the Kocher-Langenbeck approach especially when used for the
treatment of obese female patients, who have a higher risk for the development
of a saddlebag deformity. Prior to June 2001, we resected the labrum.
Thereafter, we started to refix the intact labral portion back to the osseous
acetabular rim whenever possible. As we have reported, the results of labral
refixation have been
promising9;
resection of the labrum is warranted only if there is no intact labrum
remaining. Postoperative continuous passive motion has been successful for
reducing the small but real risk of intracapsular adhesions.
The subcutaneous tissue is sharply cut, with careful hemostasis being
performed, until the iliotibial band and the fascia over the gluteus maximus
muscle are reached. In athletic young patients the gluteus maximus muscle
inserts into the iliotibial band anterior to the anterior border of the
greater trochanter, whereas in elderly patients this insertion is found more
posteriorly. The anterior border of the gluteus maximus is identified by
branches from the inferior gluteal artery that run within the fascia between
the gluteus medius and the gluteus maximus and perforate the fascia lata and
continue into the subcutaneous fat tissue
(Fig. 2). These blood vessels
are constant and help to identify the anterior border of the gluteus maximus
muscle. The blood vessels are accompanied by branches of the inferior gluteal
nerve supplying the anterior portion of the gluteus maximus; therefore, this
fascia is kept with the gluteus maximus in order to protect these structures.
From the greater trochanter to the posterior superior iliac spine, the gluteus
maximus follows a slight curve. In athletic patients, the anterior release of
the gluteus maximus needs to be performed proximally almost up to the iliac
crest, but the skin incision must not necessarily extend so far proximally.
Distally, the fascia lata is split in line with the femur. The tissue over the
greater trochanter is exposed and incised at the posterior border of the
greater trochanter. This tissue, including the bursa, is then reflected
anteriorly, away from the trochanteric crest, allowing visualization of the
vastus lateralis ridge. After exposure of the surface of the greater
trochanter, the trochanteric branch of the medial femoral circumflex artery
can be seen and coagulated before performance of the trochanteric flip
osteotomy.
The hip is prepared for the trochanteric osteotomy by internal rotation of
the joint (20° to 30°) and identification of the posterior borders of
the gluteus medius and greater trochanter
(Fig. 3). The goal is to keep
the insertions of the gluteus medius, gluteus minimus, and vastus lateralis on
the trochanteric fragment. The major part of the piriformis insertion as well
as the other external rotators remains on the femoral side of the osteotomized
trochanter (stable trochanter). It is important to keep in mind that the deep
branch of the medial femoral circumflex artery reaches the trochanter just
proximal to the quadratus femoris. It then crosses the tendon of the obturator
externus posteriorly and continues its course anterior to the superior and
inferior gemellus and the obturator internus tendon. The superior border of
the quadratus femoris can be identified easily with the level of the
trochanteric branch of the medial femoral circumflex artery
(Fig. 4). At this point, there
is no need to visualize the piriformis tendon or to mobilize the gluteus
medius muscle. The osteotomy follows a line that starts at the posterosuperior
edge of the greater trochanter and is extended distally toward the posterior
border of the vastus lateralis muscle—i.e., the vastus lateralis ridge.
The correct plane of the osteotomy lies parallel to the lower extremity
(Fig. 5). Proximally, the
osteotomy starts about 5 mm anterior to the most posterior insertion of the
gluteus medius muscle onto the tip of the trochanter. This results in a
fragment of about 15 mm in thickness at its maximum diameter. A thin
oscillating saw is used to perform the osteotomy, but it should stop at the
anterior cortex (Fig. 6). A
Lexer osteotome is used to complete the osteotomy. By levering the fragment
the anterior cortex is fractured, facilitating an easier reduction for the
trochanteric refixation. A small Hohmann retractor is then placed over the
anterior edge of the stable trochanter, and the trochanteric fragment is
flipped anteriorly as the remaining fibers of the gluteus medius and vastus
lateralis are released from the stable trochanter proximally and the femur
distally. Proximally the gluteus medius, anteriorly the gluteus minimus, and
distally the vastus lateralis remain attached to the fragment
(Fig. 7).
Near the posterosuperior tip of the trochanter, a fat pad becomes visible.
Once it has been incised, the piriformis tendon and its insertion onto the
stable trochanter can be seen. Eventually, fibers of the piriformis tendon
that remain attached to the trochanteric fragment must be cut to allow for its
further mobilization. The lower limb is now flexed and externally rotated,
allowing more anterior retraction of the mobile trochanter. The vastus
lateralis and the vastus intermedius are lifted off the lateral and anterior
aspects of the proximal part of the femur. The gluteus medius muscle is gently
retracted in an anterosuperior direction, further exposing the piriformis and
gluteus minimus muscles. One should note that the sciatic nerve crosses
underneath the piriformis and injury to it should be avoided. However,
variations of the course of the sciatic nerve with respect to the piriformis
muscle are quite frequent. The capsule is approached within the interval
between the piriformis and the gluteus minimus (Figs.
7 and
8). The gluteus minimus tendon
is sharply dissected from the underlying capsule and is retracted proximally
(Fig. 8). Now, the posterior,
superior, and, finally, the anterior aspects of the joint capsule are exposed.
The insertions of the short external rotator muscles and the piriformis muscle
are left intact, protecting the deep branch of the medial femoral circumflex
artery.
A z-shaped capsulotomy for the right hip or an inverse z-shaped capsulotomy
for the left hip now is performed (Fig.
9-A), with care being taken not to injure the labrum or cartilage.
The longitudinal limb of the capsulotomy is performed parallel to the axis of
the femoral neck, anterior to the retinaculum. It is continued medially in
line with the anterior intertrochanteric line. The incision of the
inferomedial aspect of the capsule should stop anterior to the lesser
trochanter to avoid injury to the medial femoral circumflex artery, which runs
posterosuperior to the lesser trochanter. A cuff of capsular tissue is left on
the inferior aspect of the neck for later reattachment of the capsular flap.
Injury to the small branches of the lateral femoral circumflex artery can
result from incision of the inferomedial aspect of the capsule. There is no
risk of vascular compromise when coagulating these vessels because the lateral
femoral circumflex artery does not contribute to the perfusion of the femoral
head. Finally, the proximal transverse limb is performed by incising the
capsule along the superior acetabular rim until the piriformis tendon is
reached. Doing so allows the limb to stay sufficiently (approximately 3 cm)
proximal to the capsular perforation of the medial femoral circumflex artery.
Additionally, care must be taken not to damage the underlying labrum
(Fig. 9-B).
With the joint open, the extent of intra-articular effusion and synovitis
is noted. The retinaculum with the vessels for the perfusion of the head can
be observed at the posterosuperior aspect of the neck. Any nonspherical
extension of the head becomes visible (Fig.
9-C). The site of femoro-acetabular impingement can be evaluated
by flexion-internal rotation movements
(Fig. 10). Frequently, even
with the head reduced in the acetabular undersurface, lesions of the labrum
become visible when the hip goes from flexion into extension. To allow for
inspection of the acetabulum, the femoral head is dislocated anteriorly. This
is performed by flexion and external rotation with the leg secured in the
sterile side bag (Fig. 11-A).
After subluxation with use of a bone hook that is placed around the calcar, a
curved pair of scissors is used to cut the ligamentum capitis femoris.
External rotation aids in opening up the anterior joint space and tensioning
the ligament for easier transsection (Fig.
11-B). After transsection, complete dislocation is possible.
Now it is possible to fully evaluate the femoral head-neck junction as well
as to probe the labrum and adjacent acetabular cartilage. Lowering the knee
lets the femoral head rise automatically out of the surgical site, permitting
its full inspection. Thus, no additional retractor for the femoral head is
necessary. Sometimes, for example, in tight hips, two blunt Hohmann retractors
placed around the neck are useful. For visualization of the ace-tabulum, the
knee is brought higher than the pelvis and a gentle axial push allows the head
to go posteriorly, creating enough space to view the acetabulum in its
entirety. Three retractors are inserted. One double-angled Hohmann retractor
is placed over the anterior rim of the ace-tabulum, between the labrum and the
capsule. A second, straight Hohmann retractor (8 or 16 mm) is placed on the
anterosuperior rim, close to the anterior inferior iliac spine. An easy rider
or cobra retractor is placed with its tip into the teardrop to retract the
femoral neck posteroinferiorly in order to gain further access to the
posterior and inferior parts of the acetabulum. Now, a full 360° view of
the femoral head and the acetabulum can be obtained (Figs.
12 and
13). With a blunt probe, the
integrity of the labrum and the articular
cartilage8 is
determined and the quality and quantity of any damage or injury are recorded
on specific documentation
sheets5.
If acetabular retroversion is contributing to femoro-acetabular
impingement, resection of the excessive anterior rim is performed, after the
labrum has been released temporarily and preserved for later refixation
(Figs. 14-A through 14-D). In
most instances, the intact labral periphery can be detached at its base on the
acetabular rim and the degenerated labral base and the osseous overcoverage
can be resected down to bleeding bone. The amount of acetabular rim resection
is determined on the basis of the magnitude of the damage to the acetabular
cartilage and the degree of overcoverage, but resection should not fall short
in order to avoid any instability of the hip joint. Normally, standard
anteroposterior pelvic radiographs are used to assess the acetabular coverage
preoperatively. By measuring the preoperative lateral center-edge angle and
drawing the lowest acceptable lateral center-edge angle (usually 20° to
25°), it is possible to determine the amount of bone (in millimeters) that
can be resected from the lateral acetabular rim. The resection of the
excessive portion of the acetabular rim, including the area with damaged
cartilage, is performed with use of a curved 10-mm osteotome, normally with
exposure of the well-bleeding cancellous bone of the acetabular rim. If a zone
of acetabular cartilage damage persists, microfracture can be performed. Most
acetabular rim lesions are located anterosuperiorly, close to the anterior
inferior iliac spine, and require two, three, or four bone anchors to reattach
the labrum. Currently, most titanium anchors are smaller than the absorbable
anchors and therefore match the thin anterior rim better. The anchors secure
the labrum in a position where it should heal back to the acetabular rim. It
is important to note that the refixation of the tip of the labrum (not labral
repair) requires a base of bleeding cancellous bone, which needs to be
carefully prepared. In contrast to labral repair in the shoulder, the pull-out
forces of the acetabular labrum are much lower. Positioning of the anchors is
performed under direct vision, about 2 mm away from the bone-cartilage
interface. Nonabsorbable sutures are used to avoid creating a
resorption-induced inflammatory reaction. Knots are tied on the outer
(capsular) surface, with the suture being passed through the base of the
labrum (Fig. 15). After
acetabular rim trimming and labral refixation, the acetabulum is carefully
irrigated to remove all osseous and fibrous debris and the retractors are
removed to facilitate femoral preparation.
The cartilage of the exposed femoral head is constantly irrigated. The
nonspherical portion of the femoral head is assessed with use of transparent
spherical templates. Usually, the nonspherical part of the head-neck junction
is located anterosuperiorly and is characterized by a reddish appearance of
the cartilaginous surface. Sometimes, it takes some time until the reddening
of the impingement cartilage becomes visible. In the periphery of such a
nonspherical extension, a small cyst may become visible, indicating the area
of maximum impingement. The location of these impingement cysts is mainly
anterolateral and is always distal to the physis. Gentle removal of excess
bone and recreation of a smooth femoral neck is preferred
(Fig. 16). To achieve this
goal, small curved chisels and spherical templates are used
(Fig. 17). Repetitive
intraoperative assessment of femoral head sphericity (with templates) is
performed. Excessive bone removal during the offset procedure should be
avoided, although a resection of <30% of the neck diameter has been
reported not to weaken the femoral
neck9. Furthermore,
excessive resection may compromise the sealing function of the labrum.
Anterior and anterolateral osteochondroplasty is relatively safe because most
terminal branches of the medial femoral circumflex artery enter the femoral
head through vascular foramina at the lateral and posterolateral head-neck
junction10.
Protecting these vessels is essential for preservation of the blood supply to
the femoral head. If the nonspherical portion is very lateral and
posterolateral, trimming must be executed from proximal to distal and should
stop before the entrance of the retinacular vessels is reached. The piece of
bone is broken off, and it is detached with a knife from inside-out. In this
way, even very laterally and posterolaterally localized offset alterations can
be treated.
Perfusion of the femoral head is checked by observation of the bleeding
coming from the foveolar artery or the resection surface, and laser Doppler
flowmetry is also
possible11. After
the cancellous bone surface is sealed with a thin layer of bone wax to avoid
adhesions to the capsule, the hip is reduced by manual traction on the flexed
and internally rotated knee. Sliding the femoral head over the area of labral
refixation should be avoided because this could avulse the sutured labrum.
With the head reduced, range of motion is reevaluated to determine if
flexion-internal rotation still leads to femoro-acetabular impingement. To
close the capsule, a running suture or single stitches can be used; it is
important to avoid any tension because this may stretch the retinaculum and
adversely influence the perfusion of the femoral
head11. The
trochanteric fragment is anatomically reduced and fixed with two or three 3.5
or 4.5-mm cortical screws; the screws are best aimed toward the lesser
trochanter. The screwheads should be slightly countersunk to avoid irritation
of the fascia lata. Thereafter, the various soft-tissue layers are closed with
running or single sutures. Drains are rarely used as there is almost no dead
space left behind. In women, meticulous fascial closure and subcutaneous
tissue coaptation is performed to prevent a saddlebag deformity.
The length of hospitalization averages between five and seven days.
Postoperative rehabilitation includes touch-down weight-bearing for six to
eight weeks until there is solid union of the trochanteric osteotomy site.
During the same period, the patient receives low-molecular-weight heparin to
prevent deep venous thrombosis and is prohibited from flexing the hip
>70° and from actively abducting or adducting the hip in order to allow
proper healing of the trochanteric osteotomy site. Continuous passive motion
(with flexion limited to 70°) is started on the day after surgery in order
to prevent the formation of articular adhesions between the femoral
osteochondroplasty and the capsule. Prolonged use of continuous passive motion
depends on whether or not microfracturing for acetabular cartilage damage was
necessary. In such a case, the duration may range between six and eight
weeks.