Medial tibial plateau fracture following unicompartmental knee arthroplasty – characteristics, risk factors, pathogenesis and treatment methods. Literature review and case report
Złamanie przyśrodkowego plateau kości piszczelowej po jednoprzedziałowej endoprotezoplastyce stawu kolanowego – charakterystyka, czynniki ryzyka, patogeneza i metody leczenia. Przegląd literatury i opis przypadku
Introduction. Medial tibial plateau fracture (MTPF) after medial unicompartmental knee arthroplasty
(UKA) is a rare but significant complication.
Materials and methods. MEDLINE, ScienceDirect and Cochrane Library databases were searched using
specific search terms. The inclusion criteria were articles in English, medial unicompartmental knee
arthroplasty intraoperative or stress MTPF, reported patients’ demographics and fracture characteristics,
the treatment process, any case with a follow-up for a minimum of 3 months and the reported outcome.
The exclusion criteria were lateral tibial plateau fracture, traumatic injury, all cases with a follow-up shorter
than 3 months and no reported outcome.
Results. From 374 records initially found, 36 were included in the analysis highlighting the characteristics, causes
and mechanisms of UKA-related MTPF. As to the treatment outcomes, only 10 studies with a total of 19 cases met
our inclusion and exclusion criteria. What was also reported was a case report of a 52-year-old patient diagnosed
with MTPF one week after UKA and treated using ORIF with support plate and bone augmentation. At the
8-month follow-up, the patient was complaint-free and received 88 points in the KOOS Score.
Conclusions. Several measures were proposed in the literature to minimize the risk of UKA-related MTPF.
One of them is appropriate patient selection (BMI, BMD). As to the operative technique, positioning
tibial pins too close to the medial tibial cortex and tibial plateau, extending the sagittal and vertical cut,
damaging the posterior cortex and using excessive force during hammering should be avoided. In addition,
the proper tibial component size and placement (considering the gender, race and knee alignment) is
also important. UKA-related MTPF was reported to be managed with either conservative treatment, ORIF
or revision to total knee arthroplasty (TKA). While conservative treatment carries a high risk of failure,
and the revision to TKA is a massive procedure associated with the removal of all UKA components, ORIF
was reported to bring favorable outcomes, being less invasive than revision to TKA.
Wstęp. Złamanie przyśrodkowego plateau kości piszczelowej po przyśrodkowej jednoprzedziałowej alloplastyce
stawu kolanowego jest rzadkim, ale istotnym powikłaniem.
Materiał i metody. Bazy danych MEDLINE, ScienceDirect i Cochrane Library zostały przeszukane przy użyciu
określonych haseł wyszukiwania. Kryteriami włączenia były artykuły w języku angielskim, przyśrodkowa
jednoprzedziałowa endoprotezoplastyka stawu kolanowego, śródoperacyjne lub przeciążeniowe złamanie
przyśrodkowego plateau kości piszczelowej po jednoprzedziałowej endoprotezoplastyce stawu kolanowego,
zgłoszone dane demograficzne pacjentów wraz z charakterystyką złamań, proces leczenia, każdy przypadek
z obserwacją trwającą co najmniej 3 miesiące i zgłoszonym wynikiem. Kryteriami wykluczenia były
boczne złamania kości piszczelowej, uszkodzenia pourazowe, wszystkie przypadki z okresem obserwacji
krótszym niż 3 miesiące, brak zgłoszonych wyników.
Wyniki. Spośród 374 początkowo znalezionych wyników 36 zostało włączonych do analizy podkreślającej
cechy, przyczyny i mechanizmy złamania przyśrodkowego plateau kości piszczelowej związanych z przyśrodkową
jednoprzedziałową alloplastyką stawu kolanowego. Jeśli chodzi o wyniki leczenia, tylko 10 badań
z łącznie 19 przypadkami spełniło nasze kryteria włączenia i wyłączenia. Opisano również przypadek
52-letniego pacjenta, u którego w tydzień po przyśrodkowej jednoprzedziałowej alloplastyce stawu kolanowego
zdiagnozowano złamanie przyśrodkowego plateau kości piszczelowej, które leczono otwartym
nastawieniem z wewnętrzną stabilizacją płytą podporową i augmentacją kości. Po 8 miesiącach obserwacji
pacjentka nie zgłaszała dolegliwości i uzyskała 88 punktów w skali KOOS.
Wnioski. W literaturze zaproponowano kilka środków w celu zminimalizowania ryzyka złamania przyśrodkowego
plateau kości piszczelowej związanego z jednoprzedziałową alloplastyką stawu kolanowego. Jednym
z nich jest odpowiedni dobór pacjenta (wskaźnik masy ciała, gęstość mineralna kości). Jeśli chodzi o technikę
operacyjną, należy unikać umieszczania szpilek piszczelowych zbyt blisko przyśrodkowej kory piszczelowej i
plateau piszczeli, wydłużania cięcia strzałkowego i pionowego, uszkadzania kory tylnej i używania nadmiernej
siły podczas uderzania młotkiem. Ponadto, istotny jest również odpowiedni rozmiar i umiejscowienie komponentu
piszczelowego (biorąc pod uwagę płeć, rasę i oś kolana). Zgłoszono, że złamanie przyśrodkowego plateau
kości piszczelowej po przyśrodkowej jednoprzedziałowej alloplastyce stawu kolanowego było leczone
nieoperacyjnie, otwartym nastawieniem i wewnętrzną stabilizacją lub rewizją do całkowitej endoprotezoplastyki
stawu kolanowego. Podczas gdy leczenie nieoperacyjne niesie ze sobą wysokie ryzyko niepowodzenia,
a rewizja do całkowitej endoprotezoplastyki stawu kolanowego jest masywną procedurą związaną z usunięciem
wszystkich elementów przyśrodkowej jednoprzedziałowej protezy stawu kolanowego, doniesiono, że
otwarte nastawienie i wewnętrzna stabilizacja przynosi korzystne wyniki, ponieważ jest mniej inwazyjna niż
rewizja do całkowitej endoprotezoplastyki stawu kolanowego.
Unicompartmental knee arthroplasty (UKA) is a highly effective treatment for medial compartment osteoarthritis or focal osteonecrosis in appropriately selected patients .
The main advantages over TKA are: faster recovery, fewer complications, improved patient satisfaction and better return to sport . The UKA, however, has an 8% revision rate at the 20-year follow-up and survivorship, which depends on many factors [3,4]. With medial UKA, the most common complications are aseptic loosening, a tibial fracture, polyethylene wear, bearing dislocation, disease progression, infection, and unexplained pain [5,6].
A tibial plateau fracture (TPF), after medial UKA, is a rare but significant complication, present in around 0.6% to 7.2% of UKA failures [2,6,7]. The clinical consequences of tibial fracture can be severe. Depending on the clinical picture, it can be treated conservatively with protected weight bearing, surgically with internal fixation, or with revision to TKA [7-14].
The goal of the presented study is to identify and review up-to-date literature on the subject, discuss the results of treatment options, and also present our case along with the selected treatment method, internal fixation with plate, which may be suitable to treat this complication.
Literature review – materials and methods
An electronic search of MEDLINE, ScienceDirect and Cochrane Library databases was performed in November 2020. The search included studies from 1995 to 2020 with the following terms “unicompartmental knee replacement”, “unicompartmental knee replacements”, “UKR”, “unicompartmental knee arthroplasty”, “unicompartmental knee arthroplasties”, “UKA”, “tibial plateau fracture”, “tibial plateau fractures”, “TPF”, “stress fracture”, “stress fractures”, “periprosthetic fracture” and “periprosthetic fractures”.
Afterwards, the citations were downloaded, subsequently analyzed and manually deduplicated with the use of EndNote. In the next step, source titles and abstracts were scanned. Later, full-text articles were assessed for eligibility and evaluated according to the inclusion and exclusion criteria.
Besides the aforementioned research, we also inspected databases and references in selected studies to avoid multiplying data and find information that could be helpful in decreasing the risk of the tibial plateau fracture after unicompartmental knee arthroplasty.
The PRISMA 2009 Flow Diagram illustrates the number of studies that were identified, included and excluded, as well as the reason for exclusion (Fig. 1).
Inclusion and exclusion criteria
The inclusion criteria for studies were (1) articles in English, (2) medial unicompartmental knee arthroplasty, (3) stress or intraoperative MTPF, (4) reported patient demographics and fracture characteristics, (5) the treatment process, (6) any case with a follow-up for a minimum of 3 months and (7) the reported outcome.
The exclusion criteria for studies were (1) lateral tibial plateau fracture, (2) traumatic injury, (3) all cases with a follow-up shorter than 3 months, (4) no reported outcome.
Results of the literature search
During the identification process we found 374 records. Two reviewers (BA and LJ) independently screened the titles and abstracts from all identified articles to assess their adequacy for the purpose of the research.
After the screening process, a total of 43 studies were assessed in full text. 7 articles were excluded and 36 were included in the analysis of characteristics, causes and pathogenesis of UKA-related MTPF. Within these articles, 64 cases were reported. In some cases, all data (characteristics, causes and pathogenesis) were provided, however, in some of them only partial data was available. Out of 36 studies reporting characteristics of UKA-related MTPF, only 10 studies met our inclusion and exclusion criteria for the analysis of treatment outcomes. Within these, 19 cases were reported (Fig. 1).
Onset and demographic data
Summarily, we found data concerning 10 males and 42 females. This fracture was reported more often in females (81%), than males. It can be associated with a higher occurrence of osteoporosis and with anatomical differences . The mean age was 65.3 (57 to 80). The mean onset of postoperative fractures was 11.8 (1 to 58) weeks from UKA implantation. Most commonly it occurred within the first 3 months after surgery (19 from 24 cases). There was not enough quantitative information regarding other factors like BMI, bone mineral density (BMD), postoperative valgus/varus knee angles and the postoperative posterior tibial slope angle (Tab. 1).
In 54 cases, risk factors for UKA-related MTPF were reported. We collected risk factors from these studies and counted their frequency of occurrence (Tab. 2). Low bone mineral density and high body mass index were reported to contribute to UKA-related MTPF [10,11,16-18]. Patients should be carefully selected for UKA. Inclusion criteria should include their BMI and BMD, which should be improved preoperatively.
The incorrect position of the tibial pin being too medial to the tibial cortex or too close to the tibial plateau may contribute to UKA-related MTPF. The patient’s race and knee alignment play an important role in proper tibial component size/placement. These factors should be taken into account prior to the fixation of the tibial component [5,7,9,12,15,19].
Other technical risk factors include, damage to the posterior cortex during keel groove preparation, an extended sagittal cut, an extended vertical cut, tibial re-cutting and deep tibial resection [13,17,20-22].
In 36 cases, pathogenesis for UKA-related MTPF was reported. We divided the pathogenesis of UKA-related MTPF according to occurrence time (Tab. 3). As to the intraoperative causes, the surgeon’s experience and technical skills play an important role in this procedure proving successful. Excessive force during hammering, cementing and tibial component implantation can contribute to intraoperative MTPF. Different authors suggested that using a smaller/lighter hammer, applying less force and leaving the tibial component protruded if not fully seated, may reduce the risk of UKA-related MTPF [15,21,23,24]. Familiarity and attention to the changes in instrumentation and component design is an important factor .
As to the postoperative causes of UKA-related MTPF, the most common pathogenesis is stress fracture. It may result from the factors mentioned above, as well as from the increased activity of the patient, or too early full weight-bearing walking .
In 52 cases of UKA-related MTPF, it was reported whether cement was used. Up-to-date, it is not clear whether there is an association between these types of UKA and the MTPF rate. Table 4., illustrates how many cases of UKA-related MTPF were reported in each type of UKA prosthesis (only tibial components cemented, all components cemented, uncemented or no information), however, most of these studies did not compare the occurrence of MTPF in different types of UKA prosthesis.
Four studies reported the occurrence of UKA-related MTPF in cemented and uncemented UKA [21,25-27]. Summarily, they assessed 1000 cases of cemented UKA and 3000 cases of uncemented UKA and found 0 MTPF in cemented UKA vs. 5 MTPF in uncemented UKA. What is more, one cadaveric study found that, in the case of an extended vertical cut, MPTF occurred in uncemented UKA with half of the force needed to produce the fracture in the cemented UKA .
In 19 cases, treatment outcomes were reported (Table 5).
We classified treatment as conservative only in 6 cases, when the authors gave clear information that they decided not to perform the surgery [9,11,24,29]. Non-operative treatment gave a positive result only in 3 cases with non- highly displaced UKA-related MTPF [11,29]. In three other cases this method failed, and the definitive treatment was revision to TKA [9,24]. In some other cases, the operative treatment was preceded with a period of non-weight bearing, however achieved outcomes were insufficient to give up the operative treatment [19,36].
ORIF can be performed either with the use of support plate fixation or screw fixation [10,11,13,14,24,29]. Internal fixation was used in 7 cases, including our case, and gave the best outcomes from all of the analyzed treatment methods (Table 6). While the literature is still too scanty to compare the results of fixation using a support plate vs. cannulated screws, there is cadaveric research that shows that plates present significantly higher fracture loads than fixation with cannulated screws . Kim et al., in their study concerning different UKA-related complications proposed ORIF in the case of translation or deformity of the MTPF .
In the 7 cases TKA was the primary method of choice [9,10,12,18,20]. It was reported to have good outcomes, however it also carried a high risk of complications (e.g. arthrofibrosis and patellofemoral complications) and is a massive procedure associated with the removal of all UKA components [38-40]. Some authors stated that revision to TKA may be necessary in cases of more severe complications related to MTPF such as: the abnormal position of the tibial component, the collapse of the tibial component and posterior cortex damage [10,12,20,24]. Revision to TKA can also be the definitive treatment method after initial treatment fails [9,24].
A 51-year-old female presented chronic left knee pain lasting more than 12 months. Her preoperative range of motion was 0° to 110° with a Knee Society Clinical Rating System (KSS) of 64 out of 100. Her body-mass index (BMI) was 27.4 kg/m2, indicating an overweight condition. After clinical, radiological, and intraoperative diagnosis, the patient was qualified for an unicompartmental knee arthroplasty. Pre-operative X-rays showed medial compartment knee arthritis and osteophytes of the left knee (Fig. 2A-B).
She received Oxford unicompartmental knee arthroplasty (OUKA) under navigation control with the flip over of the patella. The anterior cruciate ligament (ACL) was intact and stable. IV-degree cartilage damage of the MFC and MTC was confirmed.
With use of spigot 2 and trimming, the surface was prepared for an S-size femoral element, and under navigation control the MTC was cut.
On the basis of the readings obtained from the gauges, the tibial plateau was prepared for the A-size tibial component with a 3 mm bearing. Bone cement was prepared in an open system and after applying it the femoral and tibial components were simultaneously sealed with a 3 mm trial bearing between them. The mechanical axis of the limb was restored, and the balance was corrected in extension and flexion. The final bearing size remained unchanged. Stability of the knee was corrected; flexion was up to 140 degrees and extension was in full range of motion (ROM). Post-operative radiographs of UKA were taken within hours after the surgery. (Fig. 3A-B). No intraoperative fracture was noted.
After one week the patient reported pain, decline in ROM and an inability to fully bear weight on her left knee. Radiological assessment revealed medial periprosthetic tibial stress fracture (Fig. 4A-B). The fracture initiated on the tibial plateau, then separated the medial condyle from the tibia. After 2 months from the UKA (20/09/2019), the 52-year-old patient was scheduled for a reoperation due to the tibial plateau fracture of the left knee joint.
Support plate internal fixation of the medial plate was performed after four weeks from diagnosis. During the surgery, the fracture of the medial plateau of the left tibia, large palpebral fissure, and fracture line were approximately 2 cm below the platform. About 4-cm below the platform, a local cortical fracture was found. The reposition of the fracture was performed with bone augmentation. The medial anatomic plate of the tibial plateau was used, and 6 screws were placed proximally to fix the plate. Additionally, 1 screw, which was avoiding the keel and providing support for internal fixation, was placed. Bracing was placed for 6 weeks after surgery (Fig. A-B).
At an 8-month follow-up, the patient did not report any complaints related to the undergone surgery. During the examination the joints had a good range of motion from 0° to 120°, there was no loosening of the prosthesis, no collateral instability and no fragment displacement (Fig. 6).
The KOOS score was 88. She had an overall good outcome and despite the complications she decided to undergo UKA for the other knee.
In the literature, several measures were proposed to minimize the risk of UKA-related MTPF. One of them is appropriate patient selection (BMI, BMD). As to the operative technique, positioning tibial pins too close to the medial tibial cortex and tibial plateau, extending the sagittal and vertical cut, damaging the posterior cortex and using excessive force during hammering should be avoided. In addition, proper tibial component size and placement (considering gender, race and knee alignment) is also important. If UKA-related MTPF occurred, it was reported to be managed with either conservative treatment, ORIF, or revision to TKA. While conservative treatment carries a high risk of failure, and revision to TKA is a massive procedure associated with the removal of all UKA components, ORIF was reported to bring favorable outcomes, being less invasive than revision to TKA. Up-to-date different methods of ORIF were not directly compared.
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