KNEE

Measurement of lateral plateau depression and lateral plateauwidening in a Schatzker type II fracture can predict a lateralmeniscal injury

Mehmet Oguz Durakbasa • Ozkan Kose •

Mehmet Nurullah Ermis • Abdullah Demirtas •

Serdar Gunday • Cihangir Islam

Received: 8 February 2012 / Accepted: 27 August 2012

� Springer-Verlag 2012

Abstract

Purpose The purpose of this study is to determine the

plain radiographic signs that can be indicative of meniscal

injuries in Schatzker type II tibial plateau fractures.

Methods The lateral plateau depression and lateral pla-

teau widening were measured on anteroposterior knee

radiographs in 20 patients with Schatzker type II tibial

plateau fracture. Meniscal injury was present in 12 patients

(three, meniscal tears; nine, peripheral meniscal detach-

ments). The lateral plateau depression and lateral plateau

widening measurements were compared between those

who had meniscal injury (Group 1) and those who did not

(Group 2).

Results In Group 1, the median lateral plateau depression

was 20 mm (IQR: 14–25) and the median lateral plateau

widening was 12 mm (IQR: 10–14). In Group 2, the

respective values were 10 mm (IQR: 5–17) and 6 mm

(IQR: 2–10). There was a statistically significant difference

in both parameters when the two groups were compared

(p = 0.001).

Conclusions A plain anteroposterior radiograph depicting

a lateral plateau depression C14 mm and/or a lateral pla-

teau widening C10 mm is associated with a significantly

increased risk of meniscal injury in Schatzker type II tibial

plateau fractures. These parameters can be used to predict

the probable presence of lateral meniscal injury in such

patients in routine clinical practice.

Level of evidence Retrospective comparative study, Level

III.

Keywords Schatzker type II fracture � Plateau depression �Plateau widening � Lateral meniscal injury

Introduction

Tibia plateau fractures are complex intraarticular fractures

that usually harbour concomitant soft tissue injuries. These

injuries can be intraarticular, extraarticular or combined

[4, 8]. Schatzker type II fractures are the most commonly

encountered fracture pattern and defined as the depression

of the lateral tibial articular surface with sagittal or coronal

split [18]. Lateral meniscus is particularly susceptible to

injury in this fracture type. Meniscal tears and peripheral

meniscal detachments associated with Schatzker type II

tibia plateau fractures were reported to be associated in as

high as 90 % of the cases [8]. Preoperative identification of

meniscal injuries before any surgical intervention is

desirable as the surgeons can contemplate a more prompt

surgical strategy to repair these meniscal injuries.

The present study aims to determine the direct radio-

graphic signs of meniscal injury verified by arthrotomy

findings. Two reference lines for the radiographic param-

eters are discussed in the context of intraoperative findings.

Moreover, the details of the intraoperative findings are

delineated in order to explain the way that the lateral

meniscus detachment prevents the reduction of the fracture.

The proposed hypothesis is that a lateral plateau

depression and a lateral plateau widening in a Schatzker

type II fracture above certain threshold values strongly

suggest a lateral meniscal injury that is frequently periph-

eral detachment type.

M. O. Durakbasa (&) � O. Kose � M. N. Ermis � A. Demirtas �S. Gunday � C. Islam

2nd Department of Orthopaedics and Traumatology, Haydarpasa

Numune Education and Research Hospital, Soyak Gokyuzu

Konutlari, C Blok, D: 45, Barbaros Mah., Karayollari Site Sok.,

no: 5, 34662 Uskudar, Istanbul, Turkey

e-mail: odurakbasa@yahoo.com

123

Knee Surg Sports Traumatol Arthrosc

DOI 10.1007/s00167-012-2195-z

Materials and methods

A retrospective review of patient files as well as imaging

studies was performed to determine those with tibial plateau

fractures and treated operatively for the last 3 years. Among

39 patients detected, three were excluded because of lack of

medical data in records in one patient and substandard initial

knee radiographs in two. Remaining 36 patients with standard

AP knee plain radiographs were evaluated to determine the

type of injury. Schatzker type II fractures with a split and

depression on articular surface of the tibial lateral plateau were

detected in 20 patients. All radiographs were taken without

magnification and with keeping a 110-cm distance between

the tube and the film. The radiographic beam was centralized

to the distal pole of the patella.

The median patient age was 42 years (IQR: 28–75).

There were 14 males and six females. The mechanism of

injury was pedestrian motor vehicle accident in 12 patients,

motor vehicle accident in four, fall from height in two, and

fall onto the ground caused by a twisting injury of the knee

in two. The right-to-left ratio was 5/15. No patients gave a

history of previously known knee pain or dysfunction of

the affected knee.

All patients had been managed with open reduction and

internal fixation with the arthrotomy through the split

fragment allowing direct visualization and evaluation of

the meniscus and fracture reduction. Patients were divided

into two groups. Group 1 included the patients with men-

iscal injury, and Group 2 included those without meniscal

injury according to the operative findings.

Radiographic measurements

The plain AP radiographs were evaluated to measure two

parameters, the lateral plateau depression (LPD) and the

lateral plateau widening (LPW). The LPD was calculated in

millimetres by the difference between a reference line drawn

from the extension of the medial plateau parallel to the joint

line (a1) and a line parallel to the reference line drawn from

the maximum lateral plateau depression (a2) (Fig. 1). The

LPW was calculated in millimetres between a tangential line

to the lateral femoral epicondyle (b1) which was perpen-

dicular to a1 and a line drawn from the most lateral part of the

lateral tibial plateau (b2) which was parallel to b1 (Fig. 1).

LPD and LPW values were measured by a ruler with 1 mm

accuracy. All measurements were made by two authors, and

the mean values were used for the final analysis.

Intraoperative findings

All cases were operated on by anterior approach to the knee.

The arthrotomy was made by opening the split fragment of

the Schatzker type II fracture as a notebook page, and lateral

meniscus was explored for any peripheral detachment had

occurred or not. If there was no peripheral detachment of the

lateral meniscus, the depressed part of the fracture was ele-

vated and the space under the elevated part was filled with

spongios allograft and/or autograft. The split part was closed

onto the elevated part and the reduction was held with

Kirschner wires temporarily. An intraoperative fluoroscopy

control was made, and if reduction was satisfactory, osteo-

synthesis was performed using a lateral proximal anatomic

plate. If peripheral detachment of the lateral meniscus was

detected (Fig. 2a), the lateral meniscus was captured by an

Allis retractor, 2 no polyglactin sutures were passed into the

meniscus, and the lateral meniscus was retracted from the

joint (Fig. 2b). If the lateral meniscus was not pulled out to its

original place, the depressed part of the fracture could not be

elevated and an anatomic reduction could not be obtained.

This manoeuver also reduced the lateral femoral condyle that

was locked to the slit created by the split and the depressed

part of the fracture. The remaining part of the procedure was

the same as the nonmeniscal injury operation mentioned

previously except the lateral meniscus was sutured to the

capsule as a final step.

Fig. 1 Method of measurements. a1 = reference line drawn from the

extension of the medial plateau parallel to the joint line, a2 = lineparallel to a1 drawn from the maximum lateral plateau depression.

Lateral plateau depression (LPD) is the distance between a1 and a2.

b1 = tangential line to the lateral femoral epicondyle perpendicular

to line a1, b2 = line drawn from the most lateral part of the lateral

tibial plateau parallel to line b1. Lateral plateau widening (LPW) is

the distance between line b1 and b2

Knee Surg Sports Traumatol Arthrosc

123

Statistical analysis

The values obtained for each group were compared using

Mann–Whitney U test. The minimum LPD and the mini-

mum LPW that caused meniscal injury were set as cut-off

values. The sensitivity, the specificity, and the negative and

positive predictive values of these measurements were also

calculated. A value of p \ 0.05 was considered statistically

significant.

Results

During the operation, 12 patients were found to have

associated lateral meniscal injury (Group 1). A complete

longitudinal meniscal tear was detected in three patients

and a peripheral meniscal detachment in nine. There were

eight patients without a meniscal injury (Group 2). In

Group 1, the median LPD was 20 mm (IQR: 14–25) and

the median LPW was 12 mm (IQR: 10–14). In Group 2,

the median LPD was 10 mm (IQR: 5–17) and the median

LPW was 6 mm (IQR: 2–10). There was a statistically

significant difference in both LPD and LPW assessments

between the two groups (p = 0.001, p = 0.001) (Table 1).

The minimum LPD that caused meniscal injury was

14 mm and the minimum LPW was 10 mm. The LPD was

measured as C14 mm in 13 patients and the LPW as

C10 mm in 12. There were two patients in Group 2 who

had greater values than these thresholds, one for LPD and

one for LPW. When the cut-off value for LPD was taken as

14 mm, the sensitivity of LPD in detecting meniscal injury

was 100 %, the specificity was 87 %, and the negative and

positive predictive values were 92 and 100 %, respectively.

When the cut-off value for LPW was taken as 10 mm, the

sensitivity of LPW in detecting meniscal injury of 10 mm

was 100 %, the specificity was 87 %, and the negative and

positive predictive values were 92 and 100 %, respectively.

Discussion

This study showed that measuring LPD and LPW can give

important hints in detecting a lateral meniscal injury.

Fig. 2 a Intraoperative appearance of the peripheral meniscal

detachment. White arrow shows the tibial articular surface, asteriskshows the meniscus which is detached from the capsule. b Retraction

of lateral meniscus to its original place and repair of the detachment

with sutures to the meniscocapsular junction and elevation of the joint

line

Table 1 Summary of the results

Group 1 Group 2 Significance

Number of patients 12 8 n.s.

Median age in years 42 (IQR:

28–66)

40 (IQR:

34–75)

n.s.

Sex 10 male, 2

female

4 male, 4

female

n.s.

Median LPD in

millimetres

20 (IQR:

14–25)

10 (IQR:

5–17)

p = 0.001*

Median LPW in

millimetres

12 (IQR:

10–14)

6 (IQR:

2–10)

p = 0.001*

Group 1: patients with meniscal injury, Group 2: patients without

meniscal injury

LPD lateral plateau depression, LPW lateral plateau widening,

n.s. not significant statistically

* Statistically significant difference

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Furthermore, a peripherally detached lateral meniscus

hinders the reduction in Schatzker type II tibial plateau

fractures.

Fractures of the tibial plateau constitute 1 % of all

fractures [23]. Approximately 55–70 % of them affect the

lateral plateau, 10–23 % medial plateau and 10–30 % both

plateaus [23]. In the current study, 55 % of the fractures

were Schatzker type II, which is consistent with the pub-

lished data.

One of the major disabling long-term complications of

tibial plateau fractures is posttraumatic arthritis. Fracture

reduction and joint stability are two important factors

postulated to affect the final outcome [15, 16, 21]. Col-

lateral and cruciate ligaments together with menisci are

components providing stability to the knee joint. The

menisci function to dampen shock, increase load-bearing

area and transmit and distribute weight across the joint thus

decrease stress on the subchondral bone and increase joint

stability during movements [22]. It has been shown that

total meniscectomy increases the stress on the subchondral

bone and leads degenerative arthritis of the knee [2, 7]. The

meniscus plays a more critical role in a fractured tibial

plateau acting as roof of the damaged articular surface.

Every effort should be made to preserve or repair the

meniscus in tibial plateau fractures [23]. Therefore, it is

very important to verify the preoperative meniscal status

systematically in each tibial plateau fracture. Preoperative

identification of meniscal injuries before any surgical

intervention is desirable as the surgeons can contemplate a

more prompt surgical strategy to repair these meniscal

injuries.

Schatzker type II fractures typically occur with forced

valgus of the knee alone or combined with axial com-

pressive load at the time injury [19]. At the beginning of

this load, lateral femoral condyle impacts the lateral tibial

articular surface and causes a split fracture. When the load

propagates, lateral meniscus is entrapped between lateral

femoral condyle and lateral tibial plateau and pulled

towards medially, resulting in either a peripheral capsular

detachment or a meniscal tear depending on the direction

and amount of energy. Furthermore, a depression fracture

occurs as the lateral femoral condyle further penetrates into

the tibial plateau with trapped lateral meniscus. Hence,

peripherally detached lateral meniscus may prevent the

reduction of the Schatzker type II fracture by playing a role

as an intraarticular obstacle. The intraoperative findings

detected in this study confirmed this trauma mechanism as

we found nine peripheral lateral meniscus detachments out

of 20 cases.

Both computerized tomography (CT) and magnetic

resonance imaging (MRI) are considered to be superior

imaging modalities in assessing tibial plateau fractures by

several authors. Hackl et al. [10] reported that CT imaging

can lead to a different classification in 40 % of cases

compared to plain radiographic evaluation. Markhardt et al.

[13] stated that CT is more accurate than plain radiography

for Schatzker classification of tibial plateau fractures, and

use of cross-sectional imaging can improve surgical plan-

ning. On the other hand, evaluation of the reference lines,

LPD and LPW on a standard AP radiography is not only a

valuable tool for classifying Schatzker type II fractures but

also can be considered as complimentary to CT evaluation.

Some authors suggest MRI is the most useful imaging

modality to assess the meniscal injuries in the presence of

tibia plateau fractures because it accurately reveals the

fracture geometry together with ligamentous and meniscal

injuries [3, 12, 24]. However, MRI may not be available in

certain circumstances such as emergency settings. Addi-

tionally, routine use of MRI in every single tibial plateau

fracture is not cost-effective. The present study was

undertaken with assumption that direct radiographs that are

readily available for all trauma centres may provide valu-

able information about the presence of meniscal injuries in

such fractures.

Associated lateral meniscus injury in tibial plateau

fractures is found to be 45–91 % as by MRI [6, 8] and

71 % by arthroscopic examination [1]. The same rate was

60 % in the present series as detected during the operation.

Arthrotomy performed by opening the split fragment and

the presence of joint depression in Schatzker type II frac-

tures facilitate the visualization of the whole lateral

meniscus including the posterior horn.

Relevant literature contains conflicting data about the

relationship between degree of LPD and associated meni-

scal injuries in tibial plateau fractures. Some authors found

no correlation between the meniscal injury and either the

type of the tibial plateau fractures or the degree of

depression [6, 14]. Others found meniscal injuries to be

present in 80 % of the cases who had nondisplaced tibial

plateau fractures and treated conservatively as shown by

MRI [20]. All these studies indicate that associated meni-

scal injuries can be present independent of the degree of

articular depression and fracture type. On the other hand,

there are a few studies that postulate that the degree of LPD

and LPW can be used as the predictors of possible meniscal

injury in tibial plateau fractures by various imaging

modalities. Ringus et al. [17] concluded that patients with

C10 mm of LPD measured on CT images had an eightfold

increase in risk of having a lateral meniscus tear compared

to those with \10 mm of LPD. In another study, Gardner

et al. [9] found that 6 mm of articular depression and 5 mm

of condylar widening seen on plain radiographs were pre-

dictive of lateral meniscal injury in Schatzker type II tibial

plateau fractures. However, they did not correlate the

injuries by intraoperative findings. Similarly, the present

study showed that both LPD and LPW were associated

Knee Surg Sports Traumatol Arthrosc

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with lateral meniscal injury in Schatzker type II fractures.

Furthermore, this association was found to be correlated

with intraoperative findings. In contrast to aforementioned

studies, minimum LPD and LPW for detecting lateral

meniscal injury were found to be 14 and 10 mm,

respectively.

One of the determinants of the magnitude of the artic-

ular surface depression and lateral condylar split is the

degree of osteopenia. Impaction of cancellous bone is

expected to be greater in elderly patients leading to more

depression even with low-energy trauma due to osteopenia

[11]. In the present study, although bone mineral density of

the presented patients at the time of the injury was not

known, the average ages and sex distribution between the

two groups were similar. Asmptomatic meniscal tear

incidence has been reported to be as high as 16 % [5].

Although all patients in this study denied a previous

meniscal tear or injury, longitudinal meniscal tears detec-

ted in three patients during surgery might be present before

the injury.

The limitations of the present study are the limited number

of patients, inability to verify previous meniscal pathologies

and wide range of age that may change the extent of osteo-

penia and the degree of LPD and LPW as a consequence.

Moreover, comparison studies taking CT and/or MRI find-

ings into account could be a subject for future studies.

The present study can add to the daily practice by its two

aspects. Firstly, the LPD and LPW values calculated on the

standard anteroposterior radiograph of the knee will alert

the surgeon to evaluate the lateral meniscus peroperatively.

Secondly, the defined arthrotomy technique through the

split fragment of Schatzker type II fracture will lead the

whole lateral meniscus to be visualized and evaluated

through the depressed part of the fracture. Moreover, the

surgical technique for a successful reduction of the fracture

is described.

Conclusions

Indirect signs on AP plain knee radiographs can be used to

predict the presence of meniscal injuries, which will drive

the surgeon to plan a more prompt treatment strategy. Two

cut-off values outstand with high sensitivity and specificity

values. These are a LPD value C14 mm and a LPW value

C10 mm. Over these thresholds, a peripherally detached

lateral meniscus has to be sought by the surgical steps

delineated composed of making an arthrotomy through the

split fragment, finding the detached lateral meniscus inside

the joint to retract to its original place and to reduce the

depressed part and the lateral femoral condyle, and suturing

the lateral meniscus to the capsule.

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