Introduction
Calcaneus Tendon Ruptures
The peculiar anatomy of the calcaneal tendon, which was duly explained in the first
installment of this review article (Achilles Tendon Lesions – Part 1: Tendinopathies),
was essential for human development, being one of the main protagonists in the progress
of a quadruped into a biped animal. To obtain a firm and stable platform for bipedal
gait, the hindfoot was rotated inferiorly to touch the ground, making the gastrocnemius
one of the last muscles to stretch and gain power in the evolutionary process. The
Achilles tendon can support up to 12 times the body weight during running and accounts
for 93% of the ankle flexion torque.[1]
[2]
[3]
The microanatomy of the calcaneal tendon respects the organization of other human
tendons. Up to 95% of its cellular component is formed by tenocytes and tenoblasts.
These cells have different sizes and shapes and dispose themselves in long, parallel
chains. A total of 90% of the extracellular element is composed of collagen tissue,
predominantly type I (95%), organized in parallel bands bound by small proteoglycan
molecules. About 2% is elastin, which accounts for the tendon deformation capacity
before failure of up to 200%. Aging and the inability to provide optimal tissue healing
modify this configuration, promoting the accumulation of mucin, fibrin and types III
and VII collagen.[4]
[5]
The concentration of tissues devoid of native tensile, elastic and biological capacity
weakens tendons and predisposes them to macroscopic tears. Authors stated that these
tears would result from loads applied by a maximum muscle contraction in a tendon
in its initial stretching phase. This risk would be potentiated by a failure in the
ability of the body to control excessive and uncoordinated contractions, which are
common findings in athletes under erratic training.[6]
[7]
[8] Reported rupture mechanisms occur mainly during the detachment phase (start of running
or jumping) with the knee extended (53% of the cases), followed by inadvertent treading
on a hole (17%) and abrupt extension of a flexed ankle (10%).[9]
Acute Achilles Tendon Ruptures
Epidemiology
The Achilles tendon is the most frequently ruptured tendon in the human body, with
an annual incidence of 18 cases per 100,000 people.[10] In 1575, Ambrose-Pare was the first to describe a treatment for acute Achilles rupture
through immobilization and bandage[.11] Since then, nonsurgical treatment was the choice until the early 20th century, when surgery was routinely indicated for acute calcaneal tendon ruptures.
In the 1920s, Abrahamsen, Quenu and Stoianovitch reported the first positive results
with tenorrhaphy in this type of injury.[12]
Clinical Features
During the initial assessment, a complete history and physical examination must be
performed. Achilles tendon rupture presents three classic findings on clinical examination.
These include weakness in ankle plantar flexion, a palpable gap of ∼ 4 to 6 cm proximal
to the calcaneus and a positive Thompson sign for injury.[13] Soft tissue conditions should be evaluated for edema, bruising, previous incisions,
and integrity of other flexor muscles. Pulses are palpated and, if absent, a vascular
assessment should be considered. Medical comorbidities must also be identified, with
emphasis on diabetes mellitus and history of poor wound healing and thromboembolic
events.
Surgery, when indicated, can be performed up to 1 or even 2 weeks after the injury,
allowing swelling resolution and facilitating the positioning of suture knots. Meanwhile,
patients may be immobilized in slightly equinus, with or without weight-bearing, and
limb elevation should be encouraged. A long orthopedic boot with hindfoot heels must
be worn if weight-bearing is allowed.
Contraindications to open repair include nonambulatory status, severe peripheral arterial
disease with soft tissue compromise, poorly controlled medical comorbidities, and
inability to understand the specific postoperative rehabilitation. Smoking and diabetes
are also relative contraindications due to the significant increase in postoperative
complications.[14]
Subsidiary Exams
Ankle radiographs should be routinely obtained to ankle or posterior calcaneal tuberosity
fractures, which change planning. Kager fat pad blur is an indirect sign of Achilles
tendon injury.[15] Ultrasound (US) is the first test to be made when imaging confirmation is required.
An US may even help the therapeutic decision. A recent study revealed that gaps > 10 mm
at the first examination increased the risk of rerupture among nonsurgically treated
patients. Patients submitted to a nonsurgical treatment and presenting gaps > 5 mm
showed worse functional outcomes in 12 months.[16]
On specific occasions, a magnetic resonance imaging (MRI) may be performed to better
assess the type of rupture, since oblique and longitudinal lesions require greater
care in approach planning. Associated injuries, such as chronic Achilles tendinopathy,
are also indications for more detailed examinations, as previous and severe degenerations
may alter intra- and postoperative planning, including the need for reinforcement.
Finally, MRI may be useful to identify additional changes in the clinical examination,
such as an acute dislocation of the posterior tibial tendon in conjunction with ruptured
Achilles tendon, for instance.[17]
Nonsurgical Treatment
Historically, nonsurgical treatment has been characterized by higher rerupture rates
and a lower plantarflexion strength. However, recent protocols using functional rehabilitation
have produced better kinetic results and minor rerupture percentage.[18] Randomized controlled trials evaluated different forms of rehabilitation in nonsurgical
treatment. Immediate protected loading with early functional training is recommended
([Figure 1]) to conservatively treated patients.[19] It should be performed with a stable immobilizing boot and appropriate shims to
keep the ankle plantarflexed for the next 6 weeks. In services lacking quality functional
rehabilitation programs, nonsurgical treatment should be an exception, since surgery
decreases the risk of rerupture and loss of strength.[20]
Fig. 1 Functional conservative treatment of an acute calcaneal tendon injury using immediate
weight-bearing in a boot with edges to maintain the equinus.
Other randomized controlled trials with patients submitted to nonsurgical or surgical
treatment and the same type of functional rehabilitation showed similar clinical and
functional outcomes.[21] However, the peak force on isokinetic evaluation demonstrated that surgery (10–18%
difference compared to the contralateral side) provides better rates over 18 months
of follow-up. This trend is also seen in other high-quality studies evaluating muscle
strength in detail.[22]
[23]
[24] In fact, the vast majority of patients will experience greater plantar flexion strength
loss when the treatment is nonsurgical. However, this difference does not compromise
their daily living activities, especially in nonathletes and functionally-treated
patients.[22]
[23]
[24]
Surgical Treatment
The treatment of acute Achilles tendon ruptures is controversial and there is no consensus
in the literature regarding approach (nonsurgical versus surgical) and the ideal surgical
technique.[25] A Cochrane review assessing differences between these approaches reported that surgical
repair significantly reduces the risk of Achilles tendon rerupture, despite the higher
complication rates, including surgical wound infection.[26] Guidelines from the American Academy of Orthopaedic Surgery (AAOS) provide moderate
evidence that the nonsurgical approach has fewer complications, with higher rates
of rerupture compared to the surgical repair; in addition, it states that minimally
invasive techniques, that is, using smaller incisions, have lower complication rates
compared to open repair.[27]
The traditional open repair consists of a longitudinal, posteromedial 5- to 8-cm incision
centered in the rupture gap, with paratendon dissection, hematoma evacuation, tendon
stump debridement and Krackow technique for Direct suturing and stump overlaping.
Although this repair technique is biomechanically strong and has good overall outcomes,
it has been associated with superficial and deep wound dehiscence. In this context,
mini-open techniques are attractive as they minimize soft tissue damage and provide
a solid and firm direct repair. These attributes allowed functional gain and reduced
surgical complications.[19]
The Achilles Percutaneous Repair System (PARS; Arthrex Inc., Naples, FL, USA) is a
modern mini-open technique using a transverse skin incision of ∼ 2 cm in combination
with the introduction of a slightly curved metal apparatus inside the paratendon to
pass locking sutures. The technique allows minimal opening of deep tissues and provides
great stability to the sutured tendon ([Figure 2]). Recently, the PARS technique has been shown to accelerate recovery and return
time, as well to reduce surgical wound dehiscence rates.[28]
Fig. 2 An acute Achilles rupture treated with a minimally invasive tenorrhaphy. Forks are
introduced into the proximal stumps within the paratendon, while sutures are passed
through the device.
A biomechanical comparison of PARS repair with the mini-open technique using only
unlocked sutures revealed that PARS had the greatest strength in terms of cyclic loading
and load until failure.[29] A large recent series comparing 101 PARS and 169 traditional Achilles tendon open
repairs reported that PARS significantly reduced operative duration; in addition,
a larger number of PARS patients could return to regular physical activity 5 months
after surgery compared with open repair. The overall rate of postoperative complications
was 5% for PARS and 11% for open repair; most complications were related to dehiscence
and infections. There were no cases of rerupture, sural neuritis or deep infection
in the PARS group.[26]
Current studies do not support acute augmentation in calcaneal tendon ruptures. A
recent systematic review with meta-analysis with 169 participants (83 with reinforcement
and 86 with isolated Achilles suture) showed that there were no differences in satisfaction,
rerupture rates and complication rates.[28]
It is worth noting that the literature has also favored early and functional rehabilitation
over isolated immobilization in the first postoperative weeks, regardless of the technique
used.[29] Generally speaking, the postoperative protocol for both open and mini-open surgical
approaches is the same. Patients are kept in ∼ 20° of plantar flexion, or symmetrical
to the healthy side, for 2 weeks. Next, a removable boot is placed with Achilles-specific
shims.[30] Sutures are removed after 3 weeks, and flexion is reduced from the 4th to the 6th week. We believe that Achilles tendon protection during the first 4 weeks is crucial
due to the potential for tendon stretching. In athletic patients, onset of weight-bearing
in equinus at week 2 has resulted in safe and rapid return to sports.[17] The goal is that patients achieve full weight-bearing in neutral by the end of the
6th or 7th week. Between weeks 8 and 12, patients started wearing regular shoes, avoiding ankle
extension beyond the neutral position, using an internal heel heel edge for elevation
and protection. Activities such as running and jumping are usually allowed after 16
weeks, and 5 to 6 months are required for full return to sports.
The surgeon must decide which surgical technique to use based on his/her individual
analysis of each patient, and especially on his/her technical ability and experience.
However, increasing evidence should be considered that less invasive techniques may
be superior to the classic treatment for acute Achilles tendon tears. Treatment modality
indications based on currently available scientific evidence are summarized in [Table 1].
Table 1
|
Modality
|
Recommendation Grade
|
|
Conservative Treatment
|
B
|
|
Open Repair
|
A
|
|
Mini-Open Repair
|
A
|
Chronic Achilles Tendon Ruptures
Epidemiology
Although common, Achilles rupture still has a diagnostic failure rate at the first
medical evaluation of 20% to 25%, resulting in delayed diagnosis and treatment, which
contribute to an increased prevalence of chronic cases.[31]
[32] This high percentage has several causes, including that these patients do not seek
medical attention (many people credit symptoms to a minor muscle injury); in addition,
many individuals are unable to access specialized health services and many professionals
cannot make a correct, early diagnosis. .[33]
[34]
Some criteria may be used to define chronic lesions, including the existence of fibrous
scar tissue interposed between stumps, the presence of a large defect after separation
and retraction of the stumps, time elapsed from lesion occurrence to diagnosis > 6
weeks or symptoms of weakness and difficulty in walking and climbing stairs.[31]
[32]
[35]
Pathophysiology
Tendon rupture causes a natural separation between its ends. Right after injury, local
bleeding and regional inflammatory signaling lead to the start of reparative tissue
formation.[36] Persistence of muscle contraction and local mobilization promotes a proximal migration
of the triceps and consequent adherence of the stumps to the paratendon and adjacent
tissues.[31] An elongated fibrous scar tissue, with no mechanical capability, usually forms at
the rupture zone. In some cases, there is no healing scarring formation and a major
defect is established. Whatever the outcome, there is a substantial sural tricipital
weakness due to musculotendinous unit stretching or the lack of communication between
origin and attachment.[37]
[38]
Clinical Features
As a result of the time elapsed after the initial injury, many patients do not complain
of posterior leg pain or swelling. The evolution of the condition commonly leads these
individuals to seek care for plantar ankle flexion weakness. Although intact due to
the secondary plantarflexors integrity, this force is extremely amortized by the functional
main role of the triceps surae. This impairment directly affects daily activities
of patients, as it can incapacitate them to stand on tiptoe or walk with quality.[31]
[39]
The rich propaedeutic of an acute rupture may not be present in chronic lesions. An
irregular gait can be observed, along with ipsilateral stride shortening, intermediate
phase and second rocker increase and absence of a good limb detachment. The classic
gap may not be palpable due the presence of a regional scar tissue, which may also
confuse the Thompson test. Leg muscle hypotrophy is evident and the Matles test reveals
asymmetry between evaluated sides, corroborating the presence of the lesion.[38]
[39]
Subsidiary Exams
Although the diagnosis is essentially clinical, some ancillary tests are helpful for
picturing the condition and plan the treatment. Lateral radiographs may reveal insertional
ruptures with posterior calcaneal tuberosity avulsions. An ankle MRI is restricted
to cases of diagnostic doubt. Ultrasonography has been used to evaluate musculotendinous
stretching, with incipient results. An isokinetic study may contribute to determine
clinical weakness in patients with more not so exuberant presentations and assist
in the therapeutic decision.[39]
[40]
As knowledge evolved, the advent of a leg MRI became crucial when studying patients
with chronic Achilles tendon ruptures. Previous studies have shown changes in the
bipenation angle and muscle fatty infiltration over the course of this condition,
as discussed in the tendinopathy chapter (Achilles Tendon Lesions – Part 1: Tendinopathies).
Grade 0 and 1 fatty infiltrations (adapted Goutallier classification) in the triceps
surae permits reconstructive tendon procedures because the muscle is still functional.
Grade 2, 3 or 4 fatty degeneration demands substitution procedures with tendon transfers,
since the gastrosoleus muscle complex display irreversible losses.[39]
[41]
Nonsurgical Treatment
There is almost no space for conservative treatment in patients with chronic Achilles
tendon ruptures due to the high degree of limitation and weakness of the posterior
superficial compartment of the leg. Nonsurgical treatment must be reserved for patients
with severe comorbidities and absolute contraindications to any surgery. Conservative
treatment is based on strengthening of the secondary ankle flexors (hallux, toes,
fibularis, posterior tibialis) strengthening and in the use of anterior orthoses (AFO)
that limit ankle hyperextension and calcaneal gait.[31]
[33]
Even patients with low demand or underlying diseases that impair tissue healing (vasculopathies,
diabetes, smokers, rheumatic diseases etc.) may benefit substantially from a procedure,
especially when considering the less invasive options available today. The necessity
of surgery in patients with these profiles due the condition elevated functional disability
is another strong argument in favor of policies that prevents neglected cases. This
population could benefit from a positive outcome if they were submitted to the correct
nonsurgical treatment after an acute injury.[41]
[42]
Surgical Treatment
Traditionally, the surgical technique is chosen based on the size of the defect observed
after stump debridement and release. These flowcharts are based on expert opinions
(level V) and the proposed surgeries are supported only by level IV evidence studies.
There is still no consensus on the best technique for these ruptures.[37]
[43]
Minor failures (up to 2 cm) can be treated with direct sutures after posterior compartment
releases. Moderate defects (2 to 6 cm) can be managed with an V-Y lengthening, local
flaps or tendon transfers. Larger lesions (> 6 cm) require allografts, synthetic grafts,
releases, flaps or a combination of these methods.[43]
[44] However, these classic approaches have complication rates of up to 72%, including
dehiscence, infection, donor morbidity and loss of strength. The high rate of problems
due the long incisions and adherences has led researchers in pursuit for options with
less local aggressiveness.[45]
Current articles move towards procedures that respect local biology and the quality
of the gastrosoleus complex musculature. In the presence of grade 0 or 1 fatty infiltrations,
attempts for muscle unit salvage using tendon reconstruction are valid. In grade 2,
3 or 4 degeneration, the irrevocable muscular condition compels the surgeon to look
for triceps surae substitutes.[46]
[47]
[48]
Maffulli et al[45] published a series of papers using free grafts for chronically ruptured Achilles
tendons reconstruction through small incisions with the preservation of the skin bridge
over the tendon sacar (or gap). These authors reported good results and opened possibilities
for less morbid techniques. The proximal tendon stump (in a good quality muscle) is
prepared with the free graft (e.g., semitendinosus) and the construct is fixed to
the posterior and distal region of the posterior calcaneal tuberosity ([Figure 3]) through a tunnel with an interference screw.[45]
[49]
Fig. 3 Reconstruction of a chronic calcaneal tendon injury using an autologous semitendinosus
graft in a viable muscle semitendinosus autograft in viable muscle.
Different donor tendons are reported for transfers in chronic calcaneal tendon ruptures.
Today, it is understood that this indication is more focused on muscles with fatty
degeneration and no functionality for a potential reconstruction. The choice between
flexor hallucis longus (FHL), extensor digitorum longus or peroneal brevis should
be based on the quality of local tissues, the functional characteristics of each patient
and the expected transposition losses (loss of toe-off and sprint strength, loss of
power in the toes, loss of a secondary lateral ankle stabilizer). No technique showed
superiority to another, despite the more frequent use of FLH, which is preferred by
many authors. Less invasive techniques have also been used for transfers, currently
with the possibility of endoscopic FLH transposition ([Figure 4]).[50]
[51]
[52]
[53]
[54] Treatment indications based on currently available scientific evidence are summarized
in [Table 2].
Fig. 4 Endoscopic transfer of the flexor hallucis longus to the posterior calcaneal tuberosity
in a patient with chronic Achilles injury and fatty infiltrated triceps.
Table 2
|
Modality
|
Recommendation Grade
|
|
Open FLH or FC Transfer
|
C
|
|
VY Reconstruction
|
C
|
|
Turn Down Flaps Reconstruction
|
C
|
|
FLH Endoscopic Transfer
|
I
|
|
Free Graft Reconstruction (ST/G)
|
C
|
Final Considerations
The past two decades have been critical to the progress of knowledge about acute Achilles
tendon tears. The evolution of surgical techniques, nonoperative treatment and rehabilitation
has shed light on a topic of interest and increasing incidence. The excellent results
that can be obtained with current therapeutic modalities provide good conditions to
decide the best treatment for an specific individual. Current publications offer grade
“B” of recommendation for functional nonsurgical treatment and grade “A” for both
open and minimally invasive tenorrhaphy. Whatever the choice, it should be followed
by a dynamic rehabilitation protocol addressing early controlled mobility and weight-bearing.
Although with less exuberance, the science involving chronic Achilles tendon ruptures
also had developments. Negligence prevention policies, which would decrease the need
for major reconstructive procedures, remain virtually nonexistent. However, the morbidity
of traditional techniques has been supplanted by surgeries with greater respect for
local biology and muscle quality. Even observing that maximum degree of recommendation
is “C” for such surgical treatments, these procedures have allowed more encouraging
and much better functional results than those reported in the past.
