DOI:10.2214/AJR.07.2260
AJR 2007; 189:1169-1174
© American Roentgen Ray Society
Achilles Tendon After Percutaneous Surgical Repair: Serial MRI Observation of Uncomplicated Healing
Akira Fujikawa1,
Yukishige Kyoto1,
Masahisa Kawaguchi2,
Yutaka Naoi1 and
Yo Ukegawa2
1 Department of Radiology, Japan Self-Defense Forces Central Hospital, 1-2-24,
Ikejiri, Setagaya, Tokyo 154-8532, Japan.
2 Department of Orthopedic Surgery, Japan Self-Defense Forces Central Hospital,
Tokyo, Japan.
Received March 16, 2007;
accepted after revision May 19, 2007.
Address correspondence to A. Fujikawa.
Abstract
OBJECTIVE. The purpose of this study was to prospectively explore
the MRI features of normal healing of the expected residual tendon gap in the
Achilles tendon after percutaneous surgical repair.
SUBJECTS AND METHODS. MR images of the Achilles tendon were obtained
approximately 4, 8, and 12 weeks after surgery. Assessment of MR images was
focused on the presence of residual tendon gap and gap length, Achilles tendon
contour, and contrast enhancement in the ruptured area. Cases of open surgical
repair were used for comparison. We attempted to statistically compare the
timing of tendon gap disappearance within the percutaneous surgical repair
group and between the percutaneous and open surgical repair groups.
RESULTS. A total of 30 tendons repaired with percutaneous surgical
technique and 10 repaired with open surgical technique were evaluated. At the
first, second, and third MRI sessions of the percutaneous surgical repair
group, a residual gap was found in 100%, 80%, and none of the tendons on
T1-weighted images and in 87%, 63%, and none of the tendons on T2-weighted
images. Achilles tendon contour was visualized in 30%, 90%, and 100% of the
tendons on T1-weighted images and 90%, 100%, and 100% of the tendons on
T2-weighted images. Intratendinous enhancement was present in 100%, 73%, and
7% of the tendons in the percutaneous surgical repair group. Ring-shaped
peritendinous enhancement was recognized at the third session in all subjects.
A significantly longer time was required for tendon gap disappearance after
percutaneous than after open surgical repair.
CONCLUSION. The time course of the MR findings in the ruptured
Achilles tendon after percutaneous surgical repair appears to reflect regular
healing.
Keywords: Achilles tendon • MRI • orthopedic surgery
Introduction
Treatments of patients with acute Achilles tendon rupture include open
surgical repair, conservative therapy, and percutaneous surgical repair
[1]. Percutaneous surgical
repair is aimed at fusion of the ruptured area by suturing the Achilles tendon
and pulling the ruptured tendon ends toward each other, inducing fixation of
the tendon ends [2,
3]
(Fig. 1). Compared with open
surgical repair, percutaneous surgical repair is simpler to perform, yields
cosmetically more favorable outcome, and causes postoperative infection less
frequently. Percutaneous repair, however, carries higher risk of postoperative
rerupture and sural nerve injury
[3]. Because the optimal
management after percutaneous surgical repair is controversial at our
institution, we needed a means of objective investigation of Achilles tendons
repaired with percutaneous surgical technique. For postoperative management of
a ruptured Achilles tendon, knowledge of the baseline MRI features of the
surgically treated tendon is useful for evaluating postoperative complications
and rehabilitation protocols. Most previous studies
[4,
5] of postoperative MRI of
ruptured Achilles tendons, however, have pertained mostly to open surgical
repair. When a ruptured Achilles tendon is repaired with percutaneous
technique, the contact between the two ends of the ruptured tendon is
incomplete, and, theoretically, a residual gap persists postoperatively. Using
MRI, we examined how the inevitable gap in the tendon after percutaneous
surgical repair improves over time and when the gap eventually disappears.
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Fig. 1 —Diagram shows percutaneous surgical repair of Achilles tendon
rupture. Six stab incisions, three on medial and three on lateral aspect of
tendon, are placed at levels proximal and distal to rupture. Needles and
sutures (dashed line) are passed so that sutures are pulled to firmly
appose ruptured tendon ends. Contact between two ends of ruptured tendon is
incomplete.
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Subjects and Methods
Patients
The medical ethics committee at our institution approved the study. The
subjects were patients whose condition had been diagnosed as acute complete
Achilles tendon rupture on the basis of physical examination findings
including a positive result of a Thompson test and a palpable tendon defect
and findings on low-voltage radiography of the Achilles tendon. All patients
had undergone percutaneous surgical repair or open surgical repair within 1
week of the diagnosis. Before enrollment, each patient was informed about the
design of the study and provided written consent. Selection of the treatment
method was based on talks between the orthopedic surgeons and each patient.
For 2 weeks after surgery, the treated leg was kept in a cast in the equinus
position with no weight bearing. From the third to sixth weeks after surgery,
the degree of dorsiflexion of the ankle of the cast-immobilized leg was
gradually decreased, and partial weight bearing was started. Seven weeks after
surgery, the cast was removed, and full weight bearing was begun. Patients
underwent follow-up at an outpatient orthopedic surgical clinic for
approximately 3 months after surgery.
MRI Schedule
MRI of the Achilles tendon was performed approximately 4 weeks (3–5
weeks) (Figs. 2A,
2B,
2C,
2D), 8 weeks (7–9 weeks)
(Figs. 2E,
2F,
2G,
2H), and 12 weeks (11–13
weeks) (Figs. 2I,
2J,
2K,
2L) after surgery.
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Fig. 2A —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2B —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2C —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2D —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2E —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2F —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2G —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2H —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2I —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2J —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2K —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Fig. 2L —21-year-old man with ruptured Achilles tendon after
percutaneous surgical repair. Serial MR images obtained 28 days
(A–D), 57 days (E–H), and 87 days (I–L)
after surgery. Disappearance of tendon gap appears earlier on T2-weighted
images (A, E, and I) than on T1-weighted images (B, F,
and J). Contrast-enhanced T1-weighted images (C, G, and
K) show decrease in intratendon enhancement and increase in peritendon
enhancement as ring-shaped appearance over time. Sagittal images (D, H,
and L) were not used for measurement of gap length because of
difficulty measuring precise length.
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Imaging Protocol
We used a 1.5-T MRI system (Signa Horizon, GE Yokogawa Medical Systems)
with a commercially available quadrature cervical spinal coil or knee coil.
During MRI, the patient remained in the supine position with the affected
Achilles tendon placed on the coil. The affected leg was positioned so that
the ruptured site on the Achilles tendon was covered on the sagittal
scout-view image. The protocols were axial fat-suppressed spin-echo
T1-weighted images (TR/TE, 660/17), axial and sagittal fast spin-echo
T2-weighted images (3,500/84), and contrast-enhanced axial fat-suppressed
spin-echo T1-weighted images (660/17). Axial images were obtained with a 4-mm
section thickness, 2-mm gap, 15 x 15 cm field of view, 256 x 192
matrix, and 2 signals averaged. Sagittal images were obtained with a 3-mm
section thickness, 1-mm gap, 15 x 15 cm field of view, 256 x 192
matrix, and 2 signals averaged. For contrast-enhanced MRI, gadopentetate
dimeglumine (0.1 mmol/kg body weight, Magnevist, Schering [now Bayer Schering
Pharma AG]) or gadodiamide hydrate (0.1 mmol/kg body weight, Omniscan, Daiichi
[now GE Healthcare]) was administered IV.
Assessment
Images were evaluated by two radiologists, both blinded to the clinical
data. The assessments were based on consensus between the radiologists.
Presence or absence of tendon gap and gap length—Sagittal
images were not used because measuring the gap length was difficult owing to
the brushlike appearance of the ends of ruptured tendon (Figs.
2D,
2H, and
2L). Therefore, only axial
images were used for tendon gap evaluation. According to the definition of
tendon gap used in this study, a tendon gap was judged present in cases in
which no area of hypointensity comparable with that of the neighboring tendon
was visible in the space that had probably been occupied by the Achilles
tendon before rupture (Figs.
2A,
2B,
2C). Even when the contour of
the Achilles tendon was visible on axial images and some hypointensity was
visible within this area, a tendon gap was judged present if the hypointense
area within the contour was macroscopically smaller than approximately one
fourth of the contour or if the areas of hypointensity had a dotted
distribution (Figs. 2E,
2F,
2G). Gap length was calculated
by multiplying 6 mm (the sum of the slice thickness of 4 mm and the slice gap
of 2 mm) by the number of axial images showing a tendon gap. Gap lengths thus
were in multiples of 6 
2 mm, considering error in the first and last
slices. Because the cast was removed 7 weeks after surgery, the findings at
Achilles tendon palpation conducted by orthopedic surgeons on the days of the
second and third MRI sessions were analyzed in relation to the presence or
absence of a tendon gap on MR images.
Presence or absence of the contour of the Achilles tendon at the
rupture site—If an area showing the contour of the Achilles tendon
was visible on all axial images at the rupture site, this area was referred to
as the compartment of the Achilles tendon, whether or not the signal intensity
within this area was low enough to indicate the presence of Achilles tendon
fibers (Figs. 2A,
2B,
2C).
Presence or absence of contrast enhancement at the rupture
site—The finding of contrast enhancement within the ruptured part
of the tendon or within the incompletely repaired tendon was deemed to
indicate the presence of intratendinous enhancement whether or not enhancement
was homogeneous or inhomogeneous (Figs.
2C,
2G, and
2K). The finding of contrast
enhancement around the compartment of the Achilles tendon or around the
incompletely repaired Achilles tendon was deemed to indicate peritendinous
enhancement (Figs. 2G and
2K).
Statistical Analysis
Comparison within the percutaneous surgical repair group—To
analyze the time course of the gap after percutaneous surgical repair, the
data from the first MRI session were compared with those from the second and
third sessions by use of the Wilcoxon's signed rank test. Rather than using
the test designed for assessing the independence of the two groups to compare
the tendon gap disappearance rate between T1-weighted and T2-weighted images,
because our results were paired data obtained from the same patients, the
results were subjected to the McNemar test for paired data.
Comparison between the percutaneous and open surgical repair
groups—For comparison between the percutaneous and open surgical
repair groups, T1-weighted images and T2-weighted images were separately
analyzed for statistically significant differences. The timing of tendon gap
disappearance in the two groups was compared by use of the Mann-Whitney
U test. The percentage of tendons exhibiting gap disappearance was
compared between the two groups for each MRI session by use of Fisher's exact
test. The cumulative gap disappearance rate was calculated with the
Kaplan-Meier method, and gap disappearance thereby was deemed an event. During
this calculation, cases of rerupture and cases in which the patient did not
complete the study protocol were excluded from the population serving as the
denominator. The log-rank test was used for comparison of the cumulative gap
disappearance rate between the two groups. Data processing and statistical
analyses were performed with the computer program SAS release 8.2 TS2M0 (SAS
Institute).
Results
Patients
Between January 2000 and June 2004, 49 patients who had undergone surgical
treatment of Achilles tendon rupture were enrolled in this study. Two patients
had bilateral Achilles tendon ruptures, the timing of the rupture differing
between the two sides. In total, 51 surgically treated Achilles tendons were
studied. Forty of the 51 tendons were treated with percutaneous surgical
repair and 11 with open surgical repair. Seven tendons were not included in
follow-up because the patients had changed workplaces. Four tendons treated
with percutaneous surgical repair were excluded from the statistical analysis
because rerupture was clinically suspected, but the patients completed the
study protocol. Rerupture developed 7–8 weeks after surgery. In all four
cases, conservative treatment was started immediately after detection of
rerupture. Finally, an analysis was conducted of 30 Achilles tendons in 29
patients treated with percutaneous surgical repair (26 men, three women; age
range, 21–56 years; mean age, 39.4 years; affected side, right in 10
cases, left in 20 cases) and 10 tendons in 10 patients treated with open
surgical repair (10 men; age range, 33–49 years; mean age, 41.8 years;
affected side, right in seven cases, left in three cases).
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Fig. 3A —Changes in gap length after percutaneous suture. Dashed line
represents gap length changes in cases of rerupture of Achilles tendon during
period of observation. Four cases of rerupture of Achilles tendon were
excluded from statistical analysis. Graph shows findings on T1-weighted images
over time.
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Fig. 3B —Changes in gap length after percutaneous suture. Dashed line
represents gap length changes in cases of rerupture of Achilles tendon during
period of observation. Four cases of rerupture of Achilles tendon were
excluded from statistical analysis. Graph shows findings on T2-weighted images
over time.
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MRI Schedule
The timing of MRI varied depending on the patient's convenience and the
availability of the MRI facility. The first session was conducted 17–34
days (mean, 25.8 days), the second, 42–63 days (mean, 52.3 days), and
the third, 70–91 days (mean, 82.7 days) after surgery.
Assessment
The postoperative MRI appearance of the rupture site after percutaneous
surgical repair was not significantly different from that after open surgical
repair.
Persistent Achilles tendon gap and gap length—During the
first MRI session, T1-weighted images depicted a tendon gap in all 30 tendons
in the percutaneous and all 10 tendons in the open surgical repair group.
T2-weighted images showed a tendon gap in 26 (87%) of the tendons in the
percutaneous and in six (60%) of the tendons in the open surgical repair group
(Figs. 2A,
2B,
2C). The length of the tendon
gap during the first MRI session varied. In the percutaneous surgical repair
group, the length ranged from 6 to 48 2 mm on T1-weighted images and
from 0 to 30 2 mm on T2-weighted images. In the open surgical repair
group, the length ranged from 6 to 30 2 mm on T1-weighed images and
from 0 to 12 2 mm on T2-weighted images. During the second MRI
session, a tendon gap was found on T1-weighted images in 24 (80%) of the
tendons in the percutaneous and one (10%) of the tendons in the open surgical
repair group. T2-weighted images showed a tendon gap in 19 (63%) of the
tendons in the percutaneous but in none of the tendons in the open surgical
repair group (Figs. 2E,
2F,
2G). During the third MRI
session, neither T1-weighted nor T2-weighted images showed a tendon gap in any
case in either group (Figs.
2I,
2J,
2K). Palpation of the
surgically treated Achilles tendons on the days of the second and third MRI
sessions revealed no tendon gap except in the cases of rerupture.
Compartment of the Achilles tendon at the ruptured site—In
the percutaneous surgical repair group, the percentages of cases of Achilles
tendon compartment at the first, second, and third MRI sessions were 30%, 90%,
and 100% on T1-weighted images and 90%, 100%, and 100% on T2-weighted images.
In the open surgical repair group, the values were 60%, 80%, and 100% on
T1-weighted images and 90%, 100%, and 100% on T2-weighted images.
Contrast enhancement at the rupture site— Intratendinous
enhancement at the first, second, and third MRI sessions was present in 100%,
73%, and 7% of the tendons in the percutaneous and 100%, 60%, and 10% of the
tendons in the open surgical repair group (Figs.
2C and
2G). Peritendinous enhancement
was visualized as ring-shaped enhancement in all tendons in both groups during
the second MRI session, and it remained visible during the third MRI session
(Figs. 2G and
2K).
Statistical Analysis
Comparison within the percutaneous surgical repair
group—Tendon gap length during the second and third MRI sessions
was significantly less than that during the first session (p <
0.001, Wilcoxon's signed rank test) (Fig.
3A,
3B). Gap disappearance
occurred significantly earlier on T2-weighted than on T1-weighted images
(p = 0.063; significance level of p < 0.1, McNemar
test).
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Fig. 4A —Proportion of postoperative cases in which gap disappearance
was observed after percutaneous suture (n =40) (solid line)
and open suture (n =11) (dashed line). Difference between
two groups is statistically significant (p < 0.001, log-rank
test). Kaplan-Meier graph shows findings on T1-weighted images.
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Fig. 4B —Proportion of postoperative cases in which gap disappearance
was observed after percutaneous suture (n =40) (solid line)
and open suture (n =11) (dashed line). Difference between
two groups is statistically significant (p < 0.001, log-rank
test). Kaplan-Meier graph shows findings on T2-weighted images.
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Comparison between the percutaneous surgical repair and open surgical
repair groups—In the percutaneous surgical repair group, the time
from surgery to tendon gap disappearance was 11.6 1.5 weeks on
T1-weighted images and 10.4 3.0 weeks on T2-weighted images. In the
open surgical repair group, this period was 8.6 1.1 weeks on
T1-weighted images and 6.5 2.3 weeks on T2-weighted images. A
significantly longer time was required for tendon gap disappearance after
percutaneous surgical repair than after open surgical repair (p =
0.001, Mann-Whitney U test).
The tendon gap disappearance rate was significantly lower in the
percutaneous than in the open surgical repair group (p < 0.001,
Fisher's exact test) only at the second MRI session. A log-rank test
comparison of cumulative gap disappearance rates between the two groups
revealed a significant delay in tendon gap disappearance on both T1- and
T2-weighted images in the percutaneous compared with the open surgical repair
group (p < 0.001, log-rank test) (Fig.
4A,
4B).
Discussion
In this study, we confirmed the presence of a residual tendon gap on MR
images after percutaneous surgical repair. We estimate that the tendon gap on
MR images may represent a mixture of the inevitable gap associated with this
operative procedure and tendinous degeneration before fusion. Using a 0.1-T
MRI unit, Karjalainen et al.
[4] visualized an area of
hyperintensity at the rupture site on T2-weighted images 3 weeks after open
surgical repair and considered the hyperintense area within the tendon to
represent active scar tissue. We also found a tendon gap at the first session
even after open surgical repair. We speculate that the tendon gap consists of
a physical gap and tendinous degeneration for remodeling at the rupture site
before fusion, although we had no histologic support
[1,
4,
6–8].
A similar healing process appears to occur in the ruptured part after
percutaneous surgical repair. It therefore seems probable that the size of the
Achilles tendon gap after percutaneous surgical repair may be overestimated on
MRI compared with the anatomic size of the tendon gap immediately after
surgery.
The tendon gap at the first MRI session after percutaneous surgical repair
had disappeared 11–13 weeks after surgery irrespective of the gap length
determined on MR images (Fig.
3A,
3B). This observation suggests
that tendon continuity may be restored rapidly in the advanced stage of
healing because repair takes place over the entire tendon gap simultaneously.
In the early postoperative period, however, the speed of repair may be
affected by the time for replacement of the actual tendon gap with granulation
tissue.
During the second MR session after percutaneous surgical repair, palpation
did not confirm the presence of a tendon defect despite the tendon gap seen on
MR images obtained on the same day. This discrepancy in findings between MR
images and palpation may be explained as follows. The part visible as a tendon
gap on MR images might already have been filled with granulation tissue,
whereas mature fibrous tissue may still be absent. At palpation, the gap
filled with such granulation tissue may not be perceived as a defect in the
tendon. The result suggests, therefore, that palpation of the Achilles tendon
after surgical repair should not be used as the reference standard for
assessing tendon fusion.
An adequate blood supply is indispensable for healing of a ruptured
Achilles tendon because the flow of fibroblasts into the ruptured area is
facilitated by the blood supply
[1,
6,
7]. Fibroblasts migrate into
the ruptured part and initiate replacement of the reactive immature
granulation tissue with fibrous scar tissue. Intratendinous contrast
enhancement during the first half of the observation period is likely to be
from a combination of granulation tissue and fibrovascular scar.
Postoperative MRI of the Achilles tendon revealed a tendency for earlier
disappearance of the tendon gap on T2-weighted than on T1-weighted images.
This finding together with the change in frequency of intratendinous
enhancement suggests that T2-weighted imaging may be more sensitive for
perceiving the transition of blood-rich immature granulation tissue to fibrous
scar tissue. Care therefore is needed in regard to possible differences in
tendon gap findings related to MRI sequence.
The Achilles tendon has no synovial sheath, but the paratenon around this
tendon prevents friction between the tendon and the overlying skin. The
paratenon, a loosely arranged, thin, clear areolar connective tissue in the
peritendinous area, plays an important role in repair of the Achilles tendon
because of its involvement in the blood supply
[9,
10]. Blood is supplied to the
Achilles tendon not only in the form of intrinsic blood flow from the
musculotendinous junction but also in the form of extrinsic blood flow through
the paratenon [8,
11]. Orthopedic surgeons are
aware of two roles of the paratenon during Achilles tendon repair: prevention
of adhesion to the skin and blood supply during healing. In this study,
restoration of the compartment of the Achilles tendon preceded disappearance
of the tendon gap. Furthermore, ring-shaped contrast enhancement around the
tendon was visible after restoration of the continuity of the tendon. These
findings may suggest that the peritendinous area, possibly representing the
paratenon, is crucial for repair of a ruptured Achilles tendon.
Because the study was designed to explore MRI features of healing after
surgery, four cases of rerupture were excluded from the statistical analysis,
but the study was continued even in these four cases. The site of rerupture in
the four cases was identical to the site of the first rupture, suggesting that
the initially ruptured part of the tendon had been fragile. A finding common
to all four cases was that the tendon gap had not disappeared by the third MRI
session. In two of the four cases, cystic changes were found at the rupture
site, but this finding cannot be considered specific to rerupture. The number
of rerupture cases in the study was not large enough for a conclusion, and
rerupture is expected to assume varying patterns, such as complete and
incomplete. Furthermore, rerupture occurred 7–8 weeks after surgery, a
period identical to that during which a tendon gap continued to be visualized
on MR images in many cases. In cases in which it is difficult to make a
clinical diagnosis of rerupture, delayed tendon gap disappearance may serve as
an MRI sign of rerupture.
A major weakness of this study was a lack of reference standard for
assessing the integrity of the Achilles tendon. Histologic correlation of the
tendon gap seen on MR images would have clarified healing of the ruptured
Achilles tendon. However, invasive study would have been ethically
unacceptable. We believe that MRI is the best noninvasive method for
evaluating postoperative changes in the Achilles tendon. A minor limitation
was that repair after the 13th postoperative week was not studied. However,
the presence of incomplete replacement of the tendon gap with mature tendinous
tissue and the presence of persistent peritendinous enhancement both suggest
ongoing repair of the tendon. It was difficult to define an end point of
complete fusion in the ruptured Achilles tendon. A second minor limitation was
that because of volume averaging within each slice, the measurement we used
would seem to provide greater potential measurement error than 2
mm.
We conclude that the tendon gap visible on MR images after percutaneous
surgical repair is expected to disappear approximately 12 weeks after surgery.
The time course of the MRI features of the Achilles tendon after percutaneous
surgical repair can be considered to reflect normal healing.
References
- Maffulli N. Rupture of the Achilles tendon. J Bone Joint
Surg Am 1999; 81:1019
–1036[Free Full Text]
- Ma GW, Griffith TG. Percutaneous repair of acute closed ruptured
Achilles tendon: a new technique. Clin Orthop Relat
Res 1977; 128:247
–255[Medline]
- Bradley JP, Tibone JE. Percutaneous and open surgical repairs of
Achilles tendon ruptures: a comparative study. Am J Sports
Med 1990; 18:188
–195[Abstract/Free Full Text]
- Karjalainen PT, Aronen HJ, Pihlajamaki HK, Soila K, Paavonen T,
Bostman OM. Magnetic resonance imaging during healing of surgically repaired
Achilles tendon ruptures. Am J Sports Med1997; 25:164
–171[Abstract/Free Full Text]
- Maffulli N, Thorpe AP, Smith EW. Magnetic resonance imaging after
operative repair of Achilles tendon rupture. Scand J Med Sci
Sports 2001; 11:156
–162[CrossRef][Medline]
- Dykyj D, Jules KT. The clinical anatomy of tendons. J Am
Podiatr Med Assoc 1991; 81:358
–365[Abstract]
- Evans NA, Stanish WD. The basic science of tendon injuries.
Curr Orthop 2000;14
: 403–412[CrossRef]
- Karjalainen PT, Soila K, Aronen HJ, et al. MR imaging of overuse
injuries of the Achilles tendon. AJR2000; 175:251
–260[Abstract/Free Full Text]
- Hollenberg GM, Adams MJ, Weinberg EP. Sonographic appearance of
nonoperatively treated Achilles tendon rupture. Skeletal
Radiol 2000; 29:259
–264[CrossRef][Medline]
- Soila K, Karjalainen PT, Aronen HJ, Pihlajamaki HK, Tirman PJ.
High-resolution MR imaging of the asymptomatic Achilles tendon: new
observations. AJR 1999;173
: 323–328[Abstract/Free Full Text]
- Kvist M, Jozsa L, Jarvinen M. Vascular changes in the ruptured
Achilles tendon and paratenon. Int Orthop1992; 16:377
–382[Medline]
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Abstract
Introduction
