Keywords
patella - comminuted fracture - mesh plate - difficult patellar fracture
Introduction
Patellar fractures represent between 0.7% and 1% of all fractures.[1]
[2] Comminuted fractures correspond to type C3 on the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic
Trauma Association (AO/OTA) classification.[3] This subtype is the most frequent, representing 25% of the total.[3]
The treatment of patellar fractures seeks to restore the function of the extensor
apparatus and obtain an anatomical joint reduction together with stable fixation that
enables early rehabilitation. Achieving these objectives is more complex in the case
of comminuted patellar fractures,[4] for which there is still no consensus regarding the surgical management.[5] Total or partial patellectomy is an alternative that has been used in the past for
the management of these fractures;[6]
[7]
[8]
[9] however, it can result in loss of up to 49% of quadriceps strength,[10]
[11] and poor outcomes have been reported with its use.[10]
[12] Currently, the objective is to preserve the entire patella and, to do so, various
surgical techniques and combinations of implants have emerged that seek to achieve
better clinical results and a lower rate of complications.
Many authors have reported their results using various techniques for the management
of type-C3 patellar fractures, highlighting the use of tension band wiring with cerclage,[13]
[14]
[15]
[16]
[17]
[18] the nitinol patellar concentrator,[19]
[20]
[21] tension band wiring with minifragment plates (measuring 1.5 mm to 2.0 mm),[22]
[23]
[24]
[25] and the use of mesh plates.
The objective of the present article is to report a case of comminuted patellar fracture
managed by reduction and osteosynthesis using a mesh plate, describing the surgical
technique and ending with a review of the current literature on this type of implant.
Written informed consent was obtained from the patient for the publication of this
case and the accompanying images.
Clinical case
A 26-years-old healthy male patient who was run over by a car at low speed, which
caused a fall with support on the right upper extremity and a direct impact on the
front of the left knee.
After an evaluation in the Emergency Room of our center, he was admitted in a wheelchair,
unable to walk. The physical examination revealed increased volume, pain on patellar
palpation, and no active extension of the left knee. Through radiographs and computed
tomography (CT) scans, a comminuted left patellar fracture, type C3 on the to the
AO/OTA classification, and a Rolando fracture-dislocation of the right thumb were
diagnosed. Preoperative planning is complemented with a three-dimensional (3D) reconstruction
of the left knee CT scan ([Figure 1]). One week after the accident, the reduction and osteosynthesis of both fractures
were performed in a single procedure.
Fig. 1 Preoperative study with 3D reconstruction of a CT scan of the left knee.
Surgical technique
With the patient in supine position, a longitudinal incision is made in the midline
from the proximal edge to the distal edge of the patella. After a careful dissection
by planes, a medial traumatic retinaculotomy and a comminuted patellar fracture are
identified. Then, cleaning and careful curettage of the fracture site with a spoon
and saline solution are performed. A small non-synthesizable fragment of the medial
facet is resected, followed by fracture reduction using a forceps and three temporary
Kirschner wires. Adequate reduction is verified by direct palpation through the present
traumatic retinaculotomy and by fluoroscopy.
At the same time, on an accessory table, the 2.4 mm/2.7 mm mesh plates from the LCP
Compact Foot box set (DePuy Synthes, Raynham, MA, United States) are prepared. A plate
is placed on the reduced fracture ([Figure 2]); then, cuts and the definitive mold are made. Once its cephalocaudal size is defined,
curvatures are made at its medial and lateral ends, thus enabling the placement of
screws in the coronal plane. For the positioning of the definitive plate, temporary
olive-shaped needles are used, which enable the placement of the plate face to face
against the bone ([Figure 3]). After verifying once more the reduction and proper positioning of the mesh plate
under fluoroscopy, definitive fixation is selectively performed with screws, achieving
fixation of the comminuted fragments. After the placement of the screws, it is essential
to verify the integrity of the articular surface without the passage of the screws
by direct palpation and radioscopy. Finally, in order to optimize stability, the distal
fragment is synthesized with a 3.5-mm cannulated screw from distal to proximal. Osteosynthesis
is tested by achieving flexion of up to 30° without loss of reduction, and the procedure
is finished with cleaning and closure by tissue planes.
Fig. 2 Placement of mesh plate on reduced fracture for subsequent performance of cuts and
final molding.
Fig. 3 Transient fixation of mesh plate using olive-shaped needles.
Results
The patient evolved favorably without complications in the immediate postoperative
period. Gait rehabilitation was initiated with load bearing as tolerated with a cane
on the left side and an adapted crutch on the right side together with a passive range
of motion (ROM) of 0° to 30° for 2 weeks; then, progressive ROM was started. In the
follow-up at 3 months, the patient presented a ROM of 0° to 115° with an intact extensor
apparatus, achieving elevation of the leg in extension without difficulty ([Figures 4(A],B)). The control X-ray and CT scan showed adequate joint reduction and signs of
advanced consolidation ([Figures 5], [6(A],B)). The patient was discharged 26 months after the accident.
Fig. 4 (A,B) In the follow-up at 3 months, the patient presented a ROM of 0° to 119°, with an
intact extensor apparatus, achieving elevation of the leg in extension without difficulty.
Fig. 5 Anteroposterior radiograph of the knee exemplifying the positioning of the plate,
which is molded according to the patella with the reduced comminuted fracture.
Fig. 6 (A,B) Coronal and sagittal CT scans of the knee showing adequate joint reduction and signs
of advanced consolidation.
Discussion
Comminuted fractures of the patella are a challenge for the surgeon; as they are joint
fractures, the objective of the treatment is anatomical reduction with a stable construct
that enables early rehabilitation. As treatment alternatives, there are options such
as the use of tension band wiring with cerclage, individual screws for each fragment,
and anatomical and non-anatomical plates, among others.
Tension band wiring is the classic osteosynthesis technique for transverse patellar
fractures. In selected cases of comminuted fractures, they can be helpful, as they
do not require great technical skill and require implants available in almost every
center.[18]
[26]
[27]
[28]
[29] The disadvantage of this technique is that not all comminuted fractures are candidates
for osteosynthesis with this technique, since multidirectional fracture lines can
shear with the application of tension to the band wiring. This is why a cerclage can
be added to contain the non-synthesizable fragments with the tension band wiring and
thus increase the stability of the construct. Another disadvantage is the high rate
of removal, which, depending on the series, can reach up to 60%.[1]
Synthesis with independent screws is useful to solidify medium-sized fragments and
thus reduce the complexity of the fracture. It serves as a complement to other techniques
such as the use of tension band wiring or plates.[29]
Finally, there is the use of plates, which vary from minifragment plates to anatomical
or mesh plates. Minifragment plates have been studied by many authors,[5]
[25]
[30] and they have different possible configurations, but are limited regarding the positioning
of the screws for each fragment. In order to solve this problem, anatomical patella
plates were designed that are more versatile when it comes to synthesizing each fragment
with a screw.[22]
[23]
[24]
[31]
[32]
[33] Mesh plates enable multiple possible configurations for the screws, with a true
adaptation to the anatomy in an individualized way.[23]
[34]
[35]
[36]
[37]
[38] These plates are implants commonly used in maxillofacial surgery, spine surgery,
and neurosurgery; however, since 2015, their use has been expanded for the fixation
of patellar fractures, with reports of good results.[35]
[36]
[38]
[39] They have characteristics that make them an osteosynthesis method with some advantages
over traditional fixation methods. Among these characteristics are its multiple holes
designed for the placement of variable-angle locked screws, its easily contourable
and at the same time resistant structure, which enables its adaptation to the patient's
anatomy[35] and, lastly, its low profile, which facilitates the subcutaneous placement.[28]
[29]
[30]
[31]
[32]
[33]
Biomechanical studies[30]
[34]
[40]
[41]
[42] have evaluated the use of these plates for the treatment of patellar fractures,
showing comparable and even superior results in terms of force required for failure
compared to the standard treatment with screws and wires.
Comminuted patellar fractures are candidates for management with mesh plates, since
these can facilitate the manipulation, reduction, and fixation of multiple fragments.
Preliminary results have shown favorable outcomes and a low complication rate.[28] Lorich et al.[39] presented the use of these plates for the treatment of 9 patients with complex patellar
fractures (2 with type-34-C1 and 7 with type-34-C3 patellar fractures on the AO/OTA
classification). The authors[39] used a mesh plate that encompassed half of the circumference of the lateral half
of the patella, providing multiplanar, bicortical fixation from distal to proximal
and from lateral to medial; while the fixation from anterior to posterior was unicortical,
without compromising the articular surface. The plate is fixed to the patella using
a combination of 2.4-mm and 2.7-mm compressive screws, seeking to provide compression
and absolute stability of the main fracture fragments. Direct observation and palpation
through a lateral parapatellar arthrotomy enable the verification of the reduction
and that the articular surface has been spared. Alternatively, patellar eversion in
comminuted fractures also plays a role in the evaluation of fragment reduction, and
it has been described in some studies.[32]
[41]
[42]
[43] In their series, Lorich et al.[39] reported consolidation in all of the 9 cases in 23 weeks on average. All cases achieved
complete ROM and only one of the patients required removal of the osteosynthesis.
Singer et al.[36] reported good results with the use of these plates in a series of 9 patients with
closed comminuted patellar fractures. The average consolidation time was of 10 weeks.
Only one patient did not recover full ROM, reaching a ROM of 10° to 90°. The functional
scores (on the Lysholm scale, and the average postoperative score on the Böstman scale)
showed good and excellent results in 4 and 5 patients respectively. None of the patients
required reintervention or removal of the osteosynthesis.
Siljander et al.[38] described a retrospective series of 16 patients with patellar fractures (75% of
them comminuted) fixed with mesh plates, without loss of reduction or osteosynthesis
failure despite an unrestricted rehabilitation protocol. All fractures presented union
at 3 months of follow-up and the ROM ranged from 0° of extension to a mean flexion
of 138° (range: 115° to 151°), with a mean difference of 4.8° compared to the contralateral
ROM.
The use of these low-profile plates significantly reduces one of the most frequent
complications of patellar fractures: symptomatic osteosynthesis, reducing the need
for reintervention.[38] A reintervention rate of 37% has been reported for symptomatic osteosynthesis using
Kirschner wires[44] and tension band;[45] on the other hand, studies[28]
[36]
[38] in which mesh plates are used have not reported this type of complications or the
need for a new procedure. Possible explanations for this include the low profile of
the plate, its easy malleability, and its grid design, which enables the soft tissue
to herniate through its spaces, preventing its prominence.[38] On the other hand, Volgas and Dreger,[35] in their series of 16 patients treated with mesh plates, presented 5 cases of removal
of the osteosynthesis due to pain. Despite this, their results in terms of consolidation
and ROM were satisfactory, so the authors[35] concluded that these plates are an alternative to consider when facing a comminuted
patellar fracture or a case of non-union of a patellar fracture.
In a recent study, Vajapey et al.[28] reported the use of very low-profile mesh plates with a thickness of 0.4 mm (MatrixNEURO,
DePuy Synthes) for the management of complex patellar fractures. These plates, which
are commonly used in craniofacial surgery, were the fixation method chosen to treat
four cases of severely comminuted patellar fractures. The authors[28] reported promising results with the use of this implant, since three out of four
patients began mobility exercises early, and there were no postoperative complications;
no patient required removal of the osteosynthesis.
Among the limitations of the present study is the small number of cases included,
which is why comparative studies with a larger sample are suggested to establish results
about conventional mesh plates versus very low-profile mesh plates.
Conclusion
We presented a case of comminuted patella fracture managed with the use of a mesh
plate and an associated cannulated screw, thus avoiding partial patellectomy and its
possible complications. The patient evolved satisfactorily, achieving the expected
consolidation and early rehabilitation. The management of comminuted patellar fractures
continues to be a challenge, which is why various options have been proposed for the
treatment. An attractive alternative for the management of these injuries is the use
of mesh plates, which show favorable results and a low rate of complications in the
reviewed literature. However, studies with larger samples are required to draw conclusions
about the use of this implant; for now, it seems to be a promising choice to solve
complex cases.
