Extract
Reconstruction of the anterior cruciate ligament is one of the most
frequently performed orthopaedic procedures, with more than 100,000
reconstructions performed annually in the United States
alone1. Autogenous
bone-patellar tendon-bone graft is the graft option that is most frequently
utilized by orthopaedic surgeons in the United States, Canada, and
Europe2.
Complications have been reported to occur in association with 1.8% to 24% of
anterior cruciate ligament
reconstructions3-5.
Serious complications have included arthrofibrosis, patellar fracture,
patellar tendon rupture, tibial tubercle fracture, tibial plateau fracture,
and osteonecrosis of the femoral
condyles3-6.
Femoral fracture following anterior cruciate ligament reconstruction is a
devastating complication that has been reported only in isolated cases and has
been attributed to technical errors or the creation of additional bone holes
for supplemental fixation devices used with earlier reconstructive
techniques7-12.
We present a rare case of a supracondylar femoral fracture that occurred after
an arthroscopic anterior cruciate ligament reconstruction that had been
performed without supplemental fixation and had not been associated with
intraoperative complications. The fracture occurred through an enlarged
femoral tunnel following an injury of the involved extremity. Our patient was
informed that data concerning this case would be submitted for
publication.
Reconstruction of the anterior cruciate ligament is one of the most
frequently performed orthopaedic procedures, with more than 100,000
reconstructions performed annually in the United States
alone1. Autogenous
bone-patellar tendon-bone graft is the graft option that is most frequently
utilized by orthopaedic surgeons in the United States, Canada, and
Europe2.
Complications have been reported to occur in association with 1.8% to 24% of
anterior cruciate ligament
reconstructions3-5.
Serious complications have included arthrofibrosis, patellar fracture,
patellar tendon rupture, tibial tubercle fracture, tibial plateau fracture,
and osteonecrosis of the femoral
condyles3-6.
Femoral fracture following anterior cruciate ligament reconstruction is a
devastating complication that has been reported only in isolated cases and has
been attributed to technical errors or the creation of additional bone holes
for supplemental fixation devices used with earlier reconstructive
techniques7-12.
We present a rare case of a supracondylar femoral fracture that occurred after
an arthroscopic anterior cruciate ligament reconstruction that had been
performed without supplemental fixation and had not been associated with
intraoperative complications. The fracture occurred through an enlarged
femoral tunnel following an injury of the involved extremity. Our patient was
informed that data concerning this case would be submitted for
publication.
A thirty-three-year-old man sustained an injury of the left knee
after falling off a mountain bike. He reported that he had lost his balance
while in a standing position and had fallen onto the right side with
hyperextension of the left knee after getting his foot caught in the pedal. He
presented to the emergency room with left knee pain and the inability to bear
weight on the affected leg. A review of the history revealed that an
arthroscopic reconstruction of the left anterior cruciate ligament had been
performed five months before the time of presentation and fifteen months after
the patient had sustained an injury of the ligament. A review of the operative
record revealed that the reconstruction had been performed with use of a
10-mm-wide ipsilateral central-third patellar tendon autograft. During the
procedure, a 10-mm-wide tunnel had been drilled into the femur to a total
depth of 35 mm. Femoral tunnel placement had been performed arthroscopically
in accordance with recent
recommendations13-15
with use of a commercially available drill-guide with a 7-mm offset. Fixation
of the graft in the femoral tunnel had been achieved with use of a 7 ×
25-mm metal interference screw. A review of the operative report and an
interview with the surgeon did not reveal any intraoperative complications or
technical errors. In addition to the ligament reconstruction, arthroscopic
chondroplasty of small (grade-3) cartilage lesions of the medial and lateral
femoral condyles had been performed. The patient had recovered without
complications and had just returned to his preoperative level of athletic
activities.
Physical examination revealed marked tenderness with osseous crepitation. A
large knee effusion and marked muscle guarding prevented reliable evaluation
of ligamentous stability of the injured knee. Neurovascular function distal to
the injury was intact, and no other injuries were apparent. Plain radiographs
revealed an AO type-C1 supracondylar-bicondylar distal femoral fracture with a
large butterfly fragment involving the trochlea. The large butterfly fragment
involving the trochlea indicated an extension-type injury
(Figs. 1-A and 1-B). Computed
tomography of the left knee demonstrated that the supracondylar femoral
fracture had occurred through the intraosseous tunnel that had been created in
the posterior aspect of the distal part of the femur for fixation of the
femoral bone block of the graft (Fig.
2). Measurements on the computed tomographic images demonstrated
an increase in the diameter of the tibial tunnel to 19 mm and an increase in
the diameter of the femoral tunnel to 16 mm.
Following arthrotomy, anatomic reduction was achieved and internal fixation
was performed with use of a left distal femoral locking condylar plate
(Synthes, Paoli, Pennsylvania). After fixation, direct inspection of the
retained anterior cruciate ligament revealed an intact, well-fixed, and taut
graft throughout a full range of knee motion. Lachman testing demonstrated
<5 mm of anterior translation (grade B according to the system of the
International Knee Documentation
Committee16) with a
firm end point. In order to avoid loss of fracture fixation, pivot-shift
testing was not performed. Intraoperative examination demonstrated no varus or
valgus instability, an intact posterior cruciate ligament, and a stable
posterolateral corner. Continuous passive motion was started within six hours
after the operation, and protected weight-bearing was maintained for eight
weeks. At three months, the patient was walking without limitation. At twelve
months, complete healing of the supracondylar femoral fracture was seen on
plain radiographs (Figs. 3-A and
3-B). The range of motion of the knee was 0° to 135°
bilaterally, the result of the Lachman test was classified as grade B
according to the system of the International Knee Documentation Committee, and
the pivot-shift test was negative. KT-1000 examination with the application of
30 lb (13.6 kg) of force at 30° of knee flexion revealed a maximum
anterior tibial translation of 4 mm. Subjective knee function was rated as
good, with a Lysholm
score17 of 92
points (possible range, 0 to 100 points) and a Short Form Musculoskeletal
Function Assessment
score18 of 12
points (possible range, 100 to 0 points). There was no subjective knee
instability, and the patient had returned to pivoting sports at a recreational
level.
Anterior cruciate ligament reconstruction with use of a
bone-patellar tendon-bone autograft is one of the most frequently performed
operative
procedures2,14,15.
This procedure involves drilling a large femoral tunnel in the posterior
aspect of the lateral intercondylar notch for fixation of the proximal end of
the
graft14,15.
The effects of such defects on bone strength have become a major concern in
the field of orthopaedic trauma surgery, and their association with the risk
of a postoperative fracture of the patella or tibia after anterior cruciate
ligament reconstruction with use of a bone-patellar tendon-bone autograft has
been previously
recognized19-21.
Femoral fracture following anterior cruciate ligament reconstruction has been
reported in isolated cases as a result of distal femoral bone defects created
for extra-articular fixation of a Gore-Tex prosthetic
graft10, fixation
of a ligament-augmentation
device9, iliotibial
band tenodesis8, or
femoral post
fixation7. Femoral
fracture following anterior cruciate ligament reconstruction also has been
reported to occur in association with bone defects resulting from multiple
trocar perforations of the femoral
diaphysis11. Only
one recent report has described a lateral condylar fracture through the
femoral tunnel after anterior cruciate ligament reconstruction without
additional osseous stress
risers12.
For optimum positioning of the graft, the surgeon should place the femoral
tunnel as far posteriorly as possible while carefully avoiding disruption of
the posterior cortex. As in the case of our patient, this is commonly achieved
with use of a femoral tunnel placement guide with a built-in offset that
maintains a 1 to 2-mm thick posterior cortical rim. Disruption of the
posterior cortex can result from posterior placement of the femoral
tunnel4. This
complication is different from the fracture through the femoral tunnel that
occurred in our patient and should be carefully avoided because it can lead to
fracture of the lateral femoral
condyle7. However,
even if the posterior cortical wall is maintained, as it was in our patient,
several factors predispose the patient to the development of a distal femoral
fracture after arthroscopic anterior cruciate ligament reconstruction.
Although no studies have specifically addressed the mechanical effect of
bone tunnels, a large femoral tunnel likely acts as a localized stress
riser22-25.
This effect results from a concentration of local stresses around the femoral
defect and a reduced energy-absorbing capacity due to the decreased amount of
bone that is available to withstand the applied
load23. As bone
with stress concentration behaves in a more brittle fashion, the increased
local stresses can reach the ultimate stress of the bone at much lower applied
loads25. Depending
on the geometry of the defect, strength reductions of as much as 90% may
occur24,25.
The insertion of allogenic or autogenous bone graft into the defect, as during
bone-patellar tendon-bone ligament reconstruction, has been shown not to
significantly change the mechanical weakening of the
bone25.
Additional stress concentration in the distal part of the femur results
from the acute change of the sagittal, axial, and coronal geometry of the
posterior condylar flare and intercondylar
notch24,26.
The geometry of the distal part of the femur plays a critical role in the
structural properties of the bone and the prediction of fracture
load27,28.
Geometric analysis of the distal part of the femur has shown that the thinnest
cortical shell is located in the posterior aspect of the distal part of the
femur29; thus, the
lowest fracture load is likely to be in the anatomic region of the femoral
tunnel.
Decreased bone-mineral density of as much as 20% has been observed after
knee ligament injury, and this factor also may contribute to the increased
risk of fracture after anterior cruciate ligament reconstruction because of
decreased bending strength in the distal part of the
femur28,30.
When the area of the osseous defect is subjected to tensile stress, as it was
when our patient sustained the knee extension injury, the load strength of the
already vulnerable posterior aspect of the distal part of the femur is reduced
even
further23,24.
However, as the bone in this anatomic region is predominantly under
compression loading, the likelihood of fracture development and crack
propagation is decreased, which may explain why femoral fracture does not
occur more frequently after arthroscopic anterior cruciate ligament
reconstruction.
As the stress concentration around osseous defects has been shown to
decrease after eight to twelve weeks of osseous
remodeling24, the
predisposition for femoral fracture after anterior cruciate ligament
reconstruction would be expected to decrease. However, healing of the femoral
tunnel has been shown to be delayed by the exposure to biologic factors from
the joint31. A
previous case report on a patient in whom a fracture occurred through the
femoral tunnel two years after anterior cruciate ligament
reconstruction32
suggested that the stress-concentration effect of the femoral tunnel continues
for a prolonged period after surgery.
Bone tunnel enlargement after anterior cruciate ligament reconstruction is
well documented and has been reported to occur in as many as 68% of
cases33. The
etiology of this phenomenon is not completely understood, but it is thought to
be related to a combination of multiple biological and mechanical
factors34 and our
understanding of the clinical relevance of bone tunnel enlargement is still
evolving2,33,34.
Previous experimental studies have shown that the breaking strength of bone
decreases in direct proportion to the size of an osseous
defect22. On the
basis of these findings, the case of our patient suggests that enlargement of
the femoral tunnel may have further decreased the mechanical fracture
resistance. It has also been suggested that bone tunnel enlargement increases
the risk of tibial plateau fracture after anterior cruciate ligament
reconstruction6,19.
Given the frequency of anterior cruciate ligament reconstruction and the high
frequency of bone tunnel enlargement, the potential predisposing effect of
this phenomenon toward a fracture of the distal part of the femur needs to be
considered. Use of a more oblong drill-hole may help to reduce the stress
concentration around the defect and help to reduce the fracture
risk26.
Anatomic open reduction of the fracture is critical in order to avoid
premature arthritis. In the case of our patient, we were also able to maintain
the graft in the isometric position. Fracture fixation was successfully
achieved with minimal postoperative morbidity, early functional recovery, and
the return of a full range of motion. In contrast, other authors have reported
continued loss of knee motion or ligamentous instability after distal femoral
fracture
fixation7,9,11.
The intraoperative stability of the primary anterior cruciate ligament graft
in our patient obviated the need for revision anterior cruciate ligament
reconstruction. If anatomic fracture fixation does not maintain graft
function, removal of the primary anterior cruciate ligament graft with
bone-grafting of the enlarged bone tunnel can be performed at the time of
fracture fixation to facilitate revision anterior cruciate ligament
reconstruction at a later time.
In conclusion, supracondylar femoral fracture through the femoral bone
tunnel is a serious complication of endoscopic anterior cruciate ligament
reconstruction. The case of our patient suggests that bone tunnel enlargement
may contribute to an increased risk of distal femoral fracture due to stress
concentration around the femoral tunnel. The exact magnitude of the mechanical
weakening and the postoperative duration of the increased fracture risk are
unknown, and additional study is necessary to address these questions. If
marked bone tunnel enlargement is observed, particularly in combination with
other factors such as posttraumatic osteopenia, activity modification that
reduces tensile force on the posterior aspect of the distal part of the femur
may reduce the risk of distal femoral fracture after anterior cruciate
ligament reconstruction. ?
The authors did not receive grants or outside funding in support of their
research or preparation of this manuscript. They did not receive payments or
other benefits or a commitment or agreement to provide such benefits from a
commercial entity. No commercial entity paid or directed, or agreed to pay or
direct, any benefits to any research fund, foundation, educational
institution, or other charitable or nonprofit organization with which the
authors are affiliated or associated.
Owings MF, Kozak LJ. Ambulatory and
inpatient procedures in the United States, 1996. Vital Health Stat
13.1998;139:
1-119.1391
1998
[PubMed]
Dopirak RM, Adamany DC, Steensen RN. A
comparison of autogenous patellar tendon and hamstring tendon grafts for
anterior cruciate ligament reconstruction. Orthopedics.2004;27:
837-42.27837
2004
[PubMed]
Complications in arthroscopy: the knee and other
joints. Committee on Complications of the Arthroscopy
Association of North America. Arthroscopy.1986;2:
253-8.2253
1986
[CrossRef]
Graf B, Uhr F. Complications of
intra-articular anterior cruciate reconstruction. Clin Sports
Med.1988;7:
835-48.7835
1988
Hughston JC. Complications of anterior
cruciate ligament surgery. Orthop Clin North Am.1985;16:
237-40.16237
1985
[PubMed]
Thietje R, Faschingbauer M, Nurnberg HJ.
[Spontaneous fracture of the tibia after replacement of the anterior cruciate
ligament with absorbable interference screws. A case report and review of the
literature]. Unfallchirurg.2000;103: 594-6.
German.103594
2000
[PubMed][CrossRef]
Berg EE. Lateral femoral condyle
fracture after endoscopic anterior cruciate ligament reconstruction.
Arthroscopy.1994;10:
693-5.10693
1994
[PubMed][CrossRef]
Noah J, Sherman OH, Roberts C. Fracture
of the supracondylar femur after anterior cruciate ligament reconstruction
using patellar tendon and iliotibial tenodesis. A case report. Am J
Sports Med.1992;20:
615-8.20615
1992
[CrossRef]
Radler C, Wozasek GE, Seitz H, Vecsei V.
Distal femoral fracture through the screw hole of a ligament augmentation
device fixation. Arthroscopy.2000;16:
737-9.16737
2000
[PubMed][CrossRef]
Ternes JP, Blasier RB, Alexander AH.
Fracture of the femur after anterior cruciate ligament reconstruction with a
GORE-TEX prosthetic graft. A case report. Am J Sports Med.1993;21:
147-9.21147
1993
[PubMed][CrossRef]
Wiener DF, Siliski JM. Distal femoral
shaft fracture: a complication of endoscopic anterior cruciate ligament
reconstruction. A case report. Am J Sports Med.1996;24:
244-7.24244
1996
[PubMed][CrossRef]
Wilson TC, Rosenblum WJ, Johnson DL.
Fracture of the femoral tunnel after an anterior cruciate ligament
reconstruction. Arthroscopy.2004;20:
E45-7.20E45
2004
[PubMed][CrossRef]
Fineberg MS, Zarins B, Sherman OH.
Practical considerations in anterior cruciate ligament replacement surgery.
Arthroscopy.2000;16:
715-24.16715
2000
[PubMed][CrossRef]
Jackson DW, Kenna R, Simon TM, Kurzweil
PR. Endoscopic ACL reconstruction. Orthopedics.1993;16:
951-8.16951
1993
[PubMed]
Frank CB, Jackson DW. The science of
reconstruction of the anterior cruciate ligament. J Bone Joint Surg
Am.1997;79:
1556-76.791556
1997
Irrgang JJ, Ho H, Harner CD, Fu FH. Use
of the International Knee Documentation Committee guidelines to assess outcome
following anterior cruciate ligament reconstruction. Knee Surg Sports
Traumatol Arthrosc.1998;6:
107-14.6107
1998
[CrossRef]
Lysholm J, Gillquist J. Evaluation of
knee ligament surgery results with special emphasis on use of a scoring scale.
Am J Sports Med.1982;10:
150-4.10150
1982
[PubMed][CrossRef]
Swiontkowski MF, Engelberg R, Martin DP,
Agel J. Short musculoskeletal function assessment questionnaire: validity,
reliability, and responsiveness. J Bone Joint Surg Am.1999;81:
1245-60.811245
1999
[PubMed]
Delcogliano A, Chiossi S, Caporaso A,
Franzese S, Menghi A. Tibial plateau fracture after arthroscopic anterior
cruciate ligament reconstruction. Arthroscopy.2001;17:
E16.17E16
2001
[PubMed][CrossRef]
Brownstein B, Bronner S. Patella
fractures associated with accelerated ACL rehabilitation in patients with
autogenous patella tendon reconstructions. J Orthop Sports Phys
Ther.1997;26:
168-72.26168
1997
Jomha NM, Pinczewski LA, Clingeleffer A,
Otto DD. Arthroscopic reconstruction of the anterior cruciate ligament with
patellar-tendon autograft and interference screw fixation. The results at
seven years. J Bone Joint Surg Br.1999;81:
775-9.81775
1999
[PubMed][CrossRef]
Bechtol CO, Lepper H. Fundamental
studies in the design of metal screws for internal fixation of bone. J
Bone Joint Surg Am.1956;38:
1385.381385
1956
Brooks DB, Burstein AH, Franke VH. The
biomechanics of torsional fractures. The stress concentration effect of a
drill hole. J Bone Joint Surg Am.1970;52:
507-14.52507
1970
[PubMed]
Burstein AH, Currey J, Frankel VH,
Heiple KG, Lunseth P, Vessely JC. Bone strength. The effect of screw holes.
J Bone Joint Surg Am.1972;54:
1143-56.541143
1972
[PubMed]
Johnson BA, Fallat LM. The effect of
screw holes on bone strength. J Foot Ankle Surg.1997;36:
446-51.36446
1997
[PubMed][CrossRef]
Clark CR, Morgan C, Sonstegard DA,
Mathews LS. The effect of biopsy-hole shape and size on bone strength.
J Bone Joint Surg Am.1977;59:
213-7.59213
1977
[PubMed]
Augat P, Reeb H, Claes LE. Prediction of
fracture load at different skeletal sites by geometric properties of the
cortical shell. J Bone Miner Res.1996;11:
1356-63.111356
1996
[PubMed][CrossRef]
Stromsoe K, Hoiseth A, Alho A, Kok WL.
Bending strength of the femur in relation to non-invasive bone mineral
assessment. J Biomech.1995;28:
857-61.28857
1995
[PubMed][CrossRef]
Guy P, Krettek C, Mannss J, Whittall KP,
Schandelmaier P, Tscherne H. CT-based analysis of the geometry of the distal
femur. Injury.1998;29
Suppl 3: C16-21.29C16
1998
[PubMed][CrossRef]
Sievanen H, Kannus P, Heinonen A, Oja P,
Vuori I. Bone mineral density and muscle strength of lower extremities after
long-term strength training, subsequent knee ligament injury and
rehabilitation: a unique 2-year follow-up of a 26-year-old female student.
Bone.1994;15:
85-90.1585
1994
[PubMed][CrossRef]
Berg EE, Pollard ME, Kang Q.
Interarticular bone tunnel healing. Arthroscopy.2001;17:
189-95.17189
2001
[PubMed][CrossRef]
Manktelow AR, Haddad FS, Goddard NJ.
Late femoral condyle fracture after anterior cruciate ligament reconstruction.
A case report. Am J Sports Med.1998;26:
587-90.26587
1998
[PubMed]
Webster KE, Feller JA, Hameister KA.
Bone tunnel enlargement following anterior cruciate ligament reconstruction: a
randomised comparison of hamstring and patellar tendon grafts with 2-year
follow-up. Knee Surg Sports Traumatol Arthrosc.2001;9:
86-91.986
2001
[PubMed][CrossRef]
Wilson TC, Kantaras A, Atay A, Johnson
DL. Tunnel enlargement after anterior cruciate ligament surgery. Am J
Sports Med.2004;32:
543-9.32543
2004
[CrossRef]