Keywords
posterior cruciate ligament - preservation - primary repair - arthroscopy
The posterior cruciate ligament (PCL) is one of the four major stabilizers of the
knee joint and functions as the primary restraint to posterior tibial translation.[1] Injury to the PCL rarely occurs in isolation and is most commonly present in the
setting of multiligamentous knee injuries (MLIK).[2]
[3]
[4] In patients with a complete PCL tear and symptomatic instability, surgery is typically
preferred over conservative treatment to restore joint stability and improve functional
outcomes.[2]
[5] Despite reports of good functional outcomes after PCL reconstruction in the MLIK
over the past decades,[6] this procedure has been associated with some potential problems. These issues are
mostly related to the setting of MLIK with the significant surgical morbidity and
resultant stiffness, multiple graft usage, and the possibility for tunnel convergence.[7]
[8]
In recent years, arthroscopic primary PCL repair using modern-day advancements has
received renewed attention due to the potential advantages of this procedure over
ligament reconstruction.[9] With arthroscopic primary PCL repair, the ligament can be preserved, thereby avoiding
donor-site morbidity, which decreases surgical morbidity, and can allow early mobilization.[10]
[11] Additional benefits involve the small diameter of the bone tunnels used for suture
passage which result in less problems with tunnel convergence, especially seen in
the setting of MLIK.[12] Given these findings, arthroscopic primary PCL repair may also lead to less complicated
revision surgery than PCL reconstruction revision surgery, as is observed during the
conversion of failed ACL primary repairs.[13] Nevertheless, controversies still exist regarding this technique as the current
literature is very limited.[14]
The purpose of this review is to discuss the indications and patient selection, different
surgical techniques, rehabilitation, and outcomes of modern-day arthroscopic primary
PCL repair.
Indications and Patient Selection
Indications and Patient Selection
The most important factor for successfully repairing a torn PCL is patient selection,
which is mainly based on the tear type and tissue quality of the PCL. In this section,
we will therefore discuss the indications, preoperative imaging, and timing of surgery.
Since both proximal and distal avulsion tear types may be eligible for surgical repair,
both tear types will be discussed in further detail.
Indications
Learning from both historical and more recent studies focusing on ACL repair,[15] primary PCL repair should only be performed in patients with proximal or distal
tears since the length of tissue remnant must be sufficient to reach back to its anatomical
footprint ([Fig. 1]).[16] On the contrary, PCL reconstruction should be performed when patients present with
symptomatic midsubstance tears. Besides tear location, it is critical that tissue
quality is sufficient to withhold intrasubstance suturing and tensioning toward its
femoral or tibial anatomical insertion site.[16] When taking both tear type and tissue quality into account, some studies have suggested
that the eligibility for primary PCL repair in the MLIK setting is quite high, with
a range from 51 to 73%.[17]
[18]
Fig. 1 A sagittal T1-weighted magnetic resonance image shows a proximal (type I) posterior
cruciate ligament tear with excellent tissue quality (arrow).
Preoperative Imaging
Although standard radiographs have limited additional value in the diagnoses of acute
PCL injuries, radiographs may reveal a displaced distal avulsion fracture or show
signs of posterior tibial displacement,[19] which can be seen in chronic tears. Nevertheless, magnetic resonance imaging (MRI)
is the most important study for objectively diagnosing and analyzing PCL tears.[20]
[21] Furthermore, advanced imaging can also clearly differentiate between tear types,
and therefore, it enables orthopedic surgeons to make a preoperative assessment to
predict eligibility for primary PCL repair.[22] A recent MRI study in MLIK patients attempted to understand this association between
tear location and the possibility of repairing proximal PCL tears.[21] They found that patients were more likely to undergo primary repair if a distal
remnant length of more than 41 mm was present on MRI. It should be noted, however,
that the final decision for primary repair is always based upon arthroscopic findings
regarding tissue quality.
Timing of Surgery
Although the optimal time-frame to repair a torn PCL is currently unknown, knee ligament
repair surgery is generally preferred within the first weeks postinjury because early
surgery is crucial to optimize the likelihood of a successful repair.[22] After the first several weeks, the ligament can potentially scar and retract, leading
to suboptimal tissue quality and tissue length for adequate repair and ligament healing.[23] Before proceeding with surgery, however, the acutely injured knee should show signs
of resolving irritation and improvements in range of motion (ROM).[24] With this in mind, primary repair—either for isolated tears or in the MLIK setting—is
preferably performed between 1 and 4 weeks after injury in the senior author's practice.
Future studies, however, are needed to determine the optimal time-frame to perform
primary PCL repair.
Surgical Technique
In this section, the author's surgical preferred technique for primary repair of proximal
PCL tears will be discussed first, including two different femoral fixation techniques.
Then, we will describe our preferred surgical procedure for distal PCL tears. Finally,
other repair techniques that have been reported on in the literature will be briefly
reviewed.
Surgical Technique for Proximal Tears
The patient is placed in the supine position, prepped, and draped in the normal sterile
fashion, similar to a PCL reconstruction procedure. Anterolateral and anteromedial
portals are created, and a general inspection of the knee joint is performed. Next,
the ligamentum mucosum and some of the fat pad is resected to improve visualization.
The PCL tear can now be identified and evaluated, and any scar tissue can be debrided
as necessary by using an arthroscopic shaver. The distal remnant is then reapproximated
to its anatomical femoral insertion site with a grasper to assess if sufficient distal
remnant length is present. It is important to reduce posterior tibial luxation in
the sagittal plane with an anterior drawer force; otherwise, the ligament remnant
could appear too short for surgical repair. When tissue length and tissue quality
are sufficient to withhold intrasubstance suturing and tensioning to the anatomical
wall, the ligament is deemed repairable.
Hence, a small notchplasty can be first performed to both improve the view of the
femoral footprint and to induce healing. Suturing of the anterolateral bundle (ALB)
starts as distally as possible using the Scorpion Suture Passer (Arthrex, Naples,
FL) with a No. 2 FiberWire suture (Arthrex, Naples, FL), and is advanced proximally
in an alternating Bunnell-type pattern ([Fig. 2]). This procedure is then repeated for the posteromedial bundle (PMB) by using different
nonabsorbable sutures. Fixation of the ligament to the femoral wall can now either
be performed by using knotless suture anchor technique or using transosseous tunnels
in which the sutures are tied over a bone bridge with a button.
Fig. 2 The distal posterior cruciate ligament remnant (arrowhead) is sutured from distal
to proximal (arrow) in a Bunnell-type fashion by using a self-retriever suture-passing
device (asterisk).
When utilizing the suture anchor technique, the anterolateral portal is used for drilling
and anchor placement, whereas the anteromedial portal is used as the viewing portal.
Two 4.5 × 20 mm holes are then drilled, punched, and/or tapped (depending on bone
quality) at the native ALB and PMB insertion sides ([Fig. 3]). The PMB is then reattached first with the knee positioned at 90 degrees of flexion
by using a 4.75 mm vented BioComposite SwiveLock (Arthrex, Naples, FL), while an anterior
drawer force is being applied. The same procedure is then repeated for the ALB although
this anchor is preloaded with a high-strain suture FiberTape (InternalBrace, Arthrex,
Naples, FL), which acts as the Internal Brace that is felt to be a secondary stabilizer
and is thought to allow safer early mobilization in the early phases of rehabilitation.
A 2.4 mm drill pin is then drilled by using a PCL drill guide through the anterolateral
tibial cortex up through the tibia and exiting into the center of the tibial PCL insertion.
The FiberTape is now retrieved by using a Nitinol passing wire and channeled along
the PCL, and passes through the tibial drill hole where it is tensioned and fixed
on the anteromedial cortex of the tibia at 90 degrees of flexion by using single suture
anchor fixation, thus completing the repair ([Fig. 4]).
Fig. 3 A bone socket for the first suture anchor is drilled (asterisk) at the footprint
of the anterolateral bundle (arrow).
Fig. 4 Primary repair for a proximal posterior cruciate ligament tear is now completed (arrow).
When utilizing the transosseous tunnel technique, individual drill holes are made
through the medial femoral condyle for both the ALB and PMB. Using the PCL femoral
guide centered on the anterolateral footprint, a cannulated drill (RetroDrill; Arthrex,
Naples, FL) is used to drill from the medial side of the femur into the anterolateral
footprint ([Fig. 5]). Both sutures are then individually retrieved through each femoral bone tunnel
by using a Nitinol passing wire. The ligament remnant is then tensioned back to the
femoral wall by tensioning both sutures and applying an anterior drawer force with
the knee in 90 degrees flexion. The repair is completed after tying the sutures over
the bony bridge by using a ligament button (RetroButton; Arthrex, Naples, FL). Additional
suture augmentation can also be applied with this technique by first passing a FiberTape
through a Tightrope RT button (Arthrex, Naples, FL). This construct is then passed
and tensioned separately through the anterolateral hole where the button is engaged
and channeled along with the PCL and through the tibia as discussed above. Fixation
and tension of the suture augmentation to the tibia are performed as previously described.
Fig. 5 A posterior cruciate ligament femoral guide (asterisk) is used to drill from the
medial side of the femur into the anterolateral footprint to create two separate tunnels.
Over the last two decades, multiple arthroscopic primary repair techniques for proximal
PCL tears have been proposed.[14] Nevertheless, most authors have described similar approaches to the transosseous
tunnel technique used in the senior author's practice. However, these repair techniques
all slightly differ from our surgical procedure as there is variety in the (1) number
of independent femoral tunnels drilled, (2) number of individual sutures used, and
(3) ligament sutures techniques, such as a locking stitch or Cushing-type stitch.[25]
[26]
[27]
[28]
[29] On the contrary, only one additional augmented PCL repair was identified when reviewing
the literature.[30] Hopper et al described a modification of our transosseous tunnel technique using
FiberTape augmentation but retrieved the repair stitches proximally through one femoral
drill hole.
Surgical Technique for Distal Tears
In addition to standard anteromedial and anterolateral portal, posteromedial and posterolateral
portals are made first in standard fashion to enhance view of the remnant with the
scope in the posterolateral portal. The ALB is then sutured by using a Scorpion Suture
Passer to pass a locking stitch of FiberWire through the distal remnant. The PLB is
sutured in the same manner with the second set of sutures. A cannulated drill is then
used to drill two tunnels from the anteromedial side of the tibia into the distal
remnant's anatomical insertion site. The sutures of both bundles are now retrieved
with a nitinol passer. After applying an anterior drawer force with the knee hold
in 90 degrees of flexion, the sutures are tied down over a ligament button and the
distal repair is completed ([Fig. 6]). An Internal Brace can be added to the distal repair by adding a suture anchor
or drill hole at the ALB insertion and modifying the technique described above.
Fig. 6 Primary repair for a distal posterior cruciate ligament tear with suture augmentation
(asterisk) is now completed (arrow) in a different patient with a different knee.
Various arthroscopic and open techniques have been described in the literature for
distal avulsion tears.[31] For bony avulsion tears specifically, open reduction and internal fixation (ORIF)
remains the preferred treatment if the bony avulsion is of sufficient size, although
it should be noted that there is no consensus regarding the optimal surgical procedure.[32] These procedures include various techniques, including screws, sutures, K-wires,
staples, and toothed plates for bony fixation.[32]
Postoperative Management
Postoperative rehabilitation protocols are of critical importance for the restoration
of full ROM and achieving long-term knee stability. Optimal rehabilitation protocols
are injury dependent and based upon the specific injury pattern as most of these injuries
are MLIKs.
In general, however, all patients wear a hinged brace after surgery, which is locked
in extension during ambulation. It is important to use a brace that places an anterior
drawer force onto the proximal tibia to control any posterior tibial translation.
Immediate weight bearing and mobilization are allowed unless a meniscal repair has
been performed, in which partial weight bearing is allowed. ROM exercises are initiated
within the first postoperative days but are first limited up to 90 degrees of flexion.
Over the course of 6 weeks, this is advanced to full ROM as tolerated by the patient.
Closed-chain exercises can be initiated at 6 to 8 weeks postoperatively. Patients
can return to perform pivoting sports after 9 to 12 months when muscle strength (comparable
to the contralateral leg), ROM, patients' confidence, and sport-specific requirements
are sufficient.
Outcomes
In this section, the outcomes of arthroscopic primary repair for both proximal and
distal avulsion tears will be discussed. It is important to note; however, as isolated
PCL tears are a rare entity, most outcomes of primary PCL repair have been reported
in heterogeneous cohorts in the MLIK setting. Furthermore, several studies have reported
on minimally invasive or open PCL repair outcomes,[33]
[34] but this will remain out of scope in this review.
Proximal Tears
Wheatly et al were the first to report on a series of 13 MLIK patients treated with
arthroscopic primary repair for femoral avulsed PCL tears.[35] At a mean follow-up of 4.3 years, excellent results were noted in 11 patients (85%)
that returned for follow-up. International Knee Documentation Committee (IKDC) scores
showed normal knee function (grade A) in four patients (36.4%), and 7 (63.6%) with
nearly normal function (grade B). Furthermore, mean Lysholm and Gillquist scores were
95.4. Finally, all athletes returned to their preinjury or higher level of sports
competition.
In another small case series, Ross et al reported the outcomes of five selected patients
who were treated with arthroscopic primary PCL repair in the MLIK setting.[25] At latest follow-up, the authors described successful healing of the PCL with a
grade 1 or less posterior drawer in four patients (80%), while there was one clinical
failure.
Similar outcomes were reported by Giordano et al, as they reported on three patients
who underwent arthroscopic primary PCL repair.[26] In their study, all patients achieved clinical stability, full ROM and returned
to their preinjury competitive level at a mean follow-up of 2 years. Furthermore,
the IKDC score was normal in two of the patients and nearly normal in the third.
Heusdens et al presented in 2019 the 2-year outcomes of two patients who underwent
arthroscopic PCL repair with suture augmentation.[36] At final follow-up, both patients had excellent clinical results with full ROM,
IKDC scores of 83 and 100, Lysholm's scores of 99 and 100, and had returned to their
preinjury sports level. Additionally, MRI showed a healed and tensioned PCL in both
cases.
Vermeijden et al reported the short-term outcomes of a heterogeneous cohort of 48
patients with MLIK.[18] Of all patients, 27 (56%) presented with a PCL tear, of which 19 (73%) were repaired.
At a mean follow-up of 2.5 years, the PCL repair failed in three patients (17%), of
which two underwent ligament reconstruction and one was treated conservatively. However,
no other clinical or functional outcomes were described in this study.
Lastly, two recent case reports reported good outcomes following arthroscopic PCL
repair in the MLIK setting with concomitant repairs of the ACL and MCL.[37] Murakimi et al reported that at 2 years after surgery, their patient had a clinically
stable knee, and the Lysholm, Knee Injury and Osteoarthritis Outcome Score (KOOS)
symptoms, KOOS pain, KOOS activities of daily living, KOOS sport, and KOOS quality
of life scores were good, respectively. KT-2000 revealed a mean side-to-side difference
of 1.2 mm. Moreover, MRI showed that the PCL fibers were in continuity and under tension.
Zhao et al recently presented the case of 9-year-old patient treated with primary
PCL repair.[38] At 2-year follow-up, the patient was satisfied with his operated knee, and physical
examination showed a negative posterior drawer test and full ROM. The postoperative
Lysholm's score was 85. Finally, MRI showed consolidation of the bony fragment.
Distal Tears
In 2010, Kim et al described the outcomes of six pediatric or adolescent patients
(mean age = 12.3 years) treated with arthroscopic primary repair for distal PCL soft-tissue
avulsion tears.[39] At a mean follow-up of 3.1 years, mean side-to-side difference measured with KT-2000
arthrometer was 2.3 mm. In addition, the mean Lysholm's score was 95, and two patients
had a normal IKDC, three had a nearly normal score, while one had an abnormal score.
Finally, five of the six patients returned to their preinjury level of sports activities.
When specifically only looking at studies focusing on tibial-sided bony avulsion tears,
a recent systematic review identified 10 studies reporting on 215 patients treated
with various fixation techniques but all via an arthroscopic approach.[32] In this study, 90% had a negative or grade 1 posterior drawer test. Additionally,
the mean Lysholm's score was 95, while 78.9% reported a normal knee, 17.6% a nearly
normal knee, and 3.5% an abnormal knee according to their IKDC score. Furthermore,
mean Tegner's activity score decreased from 7.1 preinjury to 6.8 postinjury.
More recently, Yoon et al reviewed the clinical outcomes of 18 patients treated for
tibial avulsion fractures using a transosseous arthroscopic suture bridge technique
at a mean follow-up of 2.2 years.[40] No failures were reported. In addition, mean Lysholm's score was 90 and the IKDC
score was normal in 10 patients (56%), nearly normal in seven (39%) and abnormal in
one (5%). All patients achieved full ROM, and radiographic evaluation showed solid
union at the fracture site in all 18 cases.
Pooled Outcomes
When pooling all 269 patients using standardized methods,[41] the mean failure rate was 1%, reoperation rate was 6%, and complication rate was
1%. In addition, the mean Lysholm's score was 94 ± 4, IKDC subjective was 96 ± 3,
and 96% of patients had a normal or near-normal knee function according to the IKDC
objective score. Furthermore, 97% of patients reached their preinjury level of activity
level, while the Tegner's score changed from 7.1 ± 1.2 to 6.9 ± 1.1. Finally, the
mean posterior tibial translation was 1.7 ± 1.0, with 90% of patients having a negative
posterior drawer test and 93% achieving full ROM at latest follow-up. When specifically
looking at proximal and distal tears only, it was noted that considerably more data
currently is available for primary repair of distal tears (41 vs. 228 patients, respectively).
Nevertheless, failure rates in both groups were low (between and 0 and 10%), while
functional outcomes were noted to be good with mean Lysholm's and IKDC subjective
scores around 90 ([Table 1]).
Table 1
Functional and patient-reported outcomes of primary posterior cruciate ligament repair
stratified by tear location
|
Authors
|
Year
|
# pts.
|
Fail. (%)
|
Reop. (%)
|
Comp. (%)
|
Reached LOA (%)
|
Lysholm
|
Tegner
|
IKDC Obj. (%)
|
IKDC subj.
|
KT-artho.
|
Posterior drawer test
|
Full ROM (%)
|
|
Pre
|
Post
|
Neg. (%)
|
Grade I (%)
|
Grade II (%)
|
|
Primary repair of proximal PCL tears
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Giordano et al[26]
|
2011
|
3
|
0
|
0
|
0
|
100
|
97
|
|
|
100
|
94
|
|
|
|
|
100
|
|
Heusdens et al[36]
|
2019
|
2
|
0
|
0
|
0
|
100
|
99 ± 1
|
|
|
|
92 ± 9
|
2.5 ± 0.5
|
0
|
100
|
0
|
100
|
|
Murakami et al[37]
|
2020
|
1
|
0
|
0
|
0
|
100
|
99
|
|
|
|
|
1.2
|
100
|
0
|
0
|
100
|
|
Ross et al[25]
|
2003
|
5
|
20
|
0
|
|
|
|
|
|
|
|
|
|
|
20
|
|
|
Vermeijden et al[a]
[18]
|
2020
|
18
|
17
|
17
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Wheatley et al[b]
[35]
|
2020
|
11
|
0
|
9
|
0
|
100
|
95 ± 3
|
|
|
100
|
|
2.6 ± 2.1
|
45
|
55
|
0
|
91
|
|
Zhao et al[38]
|
2020
|
1
|
0
|
0
|
0
|
100
|
84
|
|
|
|
|
|
100
|
0
|
0
|
100
|
|
Primary repair of distal PCL tears
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Chen et al[b]
[42]
|
2015
|
22
|
0
|
0
|
0
|
|
92 ± 3
|
7.5 ± 0.7
|
6.7 ± 0.4
|
100
|
|
1.5 ± 0.6
|
100
|
0
|
0
|
100
|
|
Chen et al[b]
[43]
|
2012
|
36
|
0
|
0
|
6
|
|
95 ± 5
|
7.4 ± 1.6
|
7.0 ± 1.8
|
92
|
|
0.8 ± 0.8
|
|
|
|
92
|
|
Gui et al[b]
[44]
|
2009
|
24
|
0
|
8
|
0
|
|
95 ± 2
|
6.8 ± 0.4
|
6.6 ± 0.5
|
100
|
|
0.7 ± 0.8
|
96
|
4
|
0
|
92
|
|
Huang et al[b]
[45]
|
2015
|
18
|
0
|
0
|
0
|
100
|
|
|
|
100
|
|
|
100
|
0
|
0
|
89
|
|
Kim et al[b]
[46]
|
2001
|
14
|
0
|
21
|
14
|
|
|
|
|
86
|
|
1.6 ± 1.0
|
86
|
14
|
0
|
79
|
|
Kim et al[39]
|
2018
|
6
|
0
|
0
|
0
|
83
|
95 ± 3
|
|
|
83
|
|
2.3 ± 1.4
|
|
|
|
100
|
|
Pardiwala et al[b]
[47]
|
2012
|
25
|
0
|
0
|
0
|
|
89
|
|
|
100
|
|
4.1 ± 1.9
|
68
|
|
|
96
|
|
Sabat et al[b]
[48]
|
2016
|
20
|
0
|
10
|
0
|
90
|
|
7.2 ± 1.6
|
7.0 ± 1.5
|
90
|
|
1.3
|
85
|
15
|
0
|
95
|
|
Yoon et al[40]
|
2018
|
6
|
0
|
0
|
0
|
83
|
90 ± 5
|
|
7.4 ± 1.0
|
94
|
|
3.2 ± 0.4
|
|
|
|
100
|
|
Zhao et al[b]
[49]
|
2006
|
29
|
0
|
24
|
0
|
|
97 ± 1
|
6.8 ± 0.8
|
6.6 ± 0.7
|
100
|
97 ± 2
|
0.6 ± 0.4
|
97
|
3
|
0
|
93
|
|
Zhu et al[b]
[50]
|
2015
|
16
|
0
|
6
|
0
|
|
95 ± 4
|
|
|
|
94 ± 4
|
1.1 ± 0.3
|
|
|
|
94
|
|
Total proximal repair
|
41
|
10
|
4
|
0
|
100
|
96 ± 3
|
|
|
100
|
92 ± 9
|
2.7 ± 2.1
|
44
|
50
|
6
|
94
|
|
Total distal repair
|
228
|
0
|
7
|
2
|
96
|
94 ± 4
|
7.1 ± 1.2
|
6.9 ± 1.1
|
96
|
96 ± 3
|
1.6 ± 0.9
|
95
|
5
|
|
93
|
|
Total
|
269
|
1
|
6
|
1
|
97
|
94 ± 4
|
7.1 ± 1.2
|
6.9 ± 1.1
|
96
|
96 ± 3
|
1.7 ± 1.0
|
90
|
9
|
1
|
93
|
Abbreviations: Comp., complications; Fail., failures; IKDC (Obj.), percentage of patients
with grade A or B International Knee Documentation Committee score; LOA, preinjury
level of activity; KT-arthro, KT-arthrometer; Neg., negative; PCL, posterior cruciate
ligament; Pts., patients; Reop., reoperation; full ROM, percentage of patients with
full range of motion.
a Indicates that patients presented either treated for proximal tears, midsubstance
tears, or distal tears, but this study was indicated as proximal tear location since
the majority had a proximal tear (51%).[18]
b These studies have been included in a recent systematic review by Hooper et al and
which is reviewed in the outcome section.[32]
Conclusion
Over the last decade, primary PCL repair using arthroscopy has seen a resurgence of
interest. When only performing this surgery in patients with proximal or distal avulsion
type tears, good outcomes can be expected by following arthroscopic primary PCL repair.
Although the current literature regarding primary PCL repair is not extensive and
most studies have focused on heterogeneous cohorts of MLIKs, the pooled outcomes of
arthroscopic repair are excellent in patients with proximal and distal tears with
low failure rates and good subjective outcomes and objective stability. We recommend
that arthroscopic primary PCL repair should be a tool in the armamentarium of orthopedic
surgeons treating patients with isolated PCL tears or PCL tears in the MLIK setting.
