Functional Outcome of Partial Meniscectomy On Discoid Meniscus.
FUNCTIONAL OUTCOME OF PARTIAL MENISCECTOMY ON DISCOID
MENISCUS
1
I Gusti Agung Gde Dendy
2
I G N Wien Aryana
1
Resident of Orthopaedic and Traumatology Department,
Sanglah General Hospital, Udayana University, Bali
2
Staff of Orthopaedic and Traumatology Department,
Sanglah General Hospital, Udayana University, Bali
BACKGROUND
Discoid meniscus is common congenital anatomical anomaly of the meniscus. A discoid
meniscus has abnormal morphology. It is thicker and covers more of the tibial plateau. The
cause of discoid meniscus is unknown, though there are some theories by Smillie and
Kaplan. Watanabe describe discoid meniscus as complete, incomplete, and Wrisberg type.
The physical examination usually showed pain, swelling, joint tenderness, effusion, limited
extension, and classic audible “snapping knee”. The most accurate criteria for the diagnosis
of discoid meniscus on radiograph is MRI. Surgical treatment necessary for those
symptomatic conditions by partial or total meniscectomy.
CASE PRESENTATION
A 9-year-old female presented with a one-year history of knee pain in her right knee.
Physical examination revealed a limited range of motion of flexion and extension also
audible click sound McMurray. On radiograph showed a flattening of tibial plateau and
widening of joint space with an increasing ratio of the minimal meniscal width to maximal
tibial width on the coronal slice of more than 20%. Patient undergone partial meniscectomy
and 6 months post operatively, patient showed a good result based on WOMAC index.
DISCUSSION
After the partial meniscectomy patient followed up and examined with WOMAC Score.
Patient can do normal daily activity without pain and limitation of movement on her right
knee. She can do flexion and extension on her knee fully without pain and audible click
1
sound. WOMAC Score after partial meniscectomy the score was 8,3 %. The score indicate
there is no significant pain, joint stiffness and difficulty on physical activity. After the
operation patient can do her normal daily activity, and there is no complained on her knee
anymore.
CONCLUSIONS
This study has shown that treatment of discoid meniscus with Partial Meniscectomy in
children is consider to get satisfactory functional outcome based on WOMAC index
Keyword :discoid meniscus, arthroscopy, partial meniscectomy,WOMAC index
2
BACKGROUND
Discoid meniscus, a common anatomical anomaly of the meniscus, was first described by
Young in 1889. In the fetus the meniscusis is disc-like; if this shape persists, symptoms are
likely.1 Discoid meniscus is an uncommon meniscal anomaly that occurs more frequently
laterally than medially.2 The normal menisci differentiate within the limb bud from
mesenchymal tissue early during fetal development. They gain mature anatomical shape at
the 14th week, without ever possessing a discoid shape. By 9 months of life, the central third
becomes avascular, and only the peripheral third retains its blood supply at adulthood. The
inner two-thirds receive nourishment via diffusion from the intra-articular fluid. In adults, the
C-shaped medial meniscus covers 50% of the medial tibial plateau and is connected firmly to
the joint capsule.3
A discoid meniscus has abnormal morphology. It is thicker and covers more of the tibial
plateau. The incidence of lateral discoid meniscus is 0.4% to 17%5, compared to 0.06% to
0.3%for the medial one. 20% of discoid lateral meniscus are bilateral, whereas bilateral
discoid medial meniscus is rare. The incidence is estimated to be 3% to 5% in the general
population and slightly higher in Asian populations The precise cause of discoid meniscus is
unknown, though there are some theories.3,4
Several theories describe the pathology of these anatomies. Smillie suggested that the
discoid shape is an intermediate stage during the fetal state, and that occurrence of the final
discoid morphology is caused by absorption failure of the central part of the menisci
(“congenital discoid meniscus”). Kaplan suggested that deficiency of the posterior meniscal
attachments causes meniscal hyper mobility, leading to a high incidence of repetitive
microtrauma that results in morphological changes. Kaplan‟s theory, however, makes no
3
sense in cases with normal posterior attachments. The congenital theory is supported by
reports of familial transmission and of the anomaly occurring in twins.3,4
Smillie first classified discoid meniscus into three types: the primitive type that affects the
whole disc, the intermediate type that is smaller and less complete, and the infantile type,
which differs in that the middle segment has greatly increased breadth. Watanabe et al
classified various types of lateral discoid meniscus based on its arthroscopic appearance and
on the basis of the degree of coverage of the lateral tibial plateau and the presence or absence
of the normal posterior meniscotibial attachment as; complete, incomplete, and Wrisberg
type.2 Discoid menisci with normal peripheral attachments were labeled as either type I
(complete) or type II (incomplete) according to the degree of coverage of the lateral tibial
plateau. Type III (also the Wrisberg ligament type) includes cases without normal posterior
meniscotibial attachment, thus allowing increased mobility and producing the classic
„„snapping knee‟‟ syndrome. Wrisberg-type discoid menisci often occur at a younger age
than complete or incomplete types and are unassociated with trauma. If an incomplete or
complete discoid meniscus is torn, symptoms are similar to those of any other meniscal tear:
lateral joint line tenderness, clicking, and effusion. 3,4
If there is only a clunk, treatment is not essential.1 Stable discoid meniscus, especially
an intact, complete or incomplete discoid meniscus usually seen as an incidental finding at
arthroscopy, does not necessarily require treatment until develop tears or degeneration within
the meniscus. Unstable discoid meniscus produces the classical „„snapping knee‟‟. It is
usually related to Wrisberg ligament type, but it can also be seen when a torn stable discoid
meniscus becomes unstable due to spread of a tear that includes the posterior tibial
4
attachment.3,4 On physical examination, the patient may present with pain, swelling, joint
line tenderness,
effusion, limited extension, and anterolateral bulge at full flexion.
McMurray test may be positive, but it is not typical especially in young children. A true
locking is a rare presentation; whereas pseudo-locking more often occur, but requires no
specific maneuver to restore range of motion.3,4
Conventional imaging radiograph usually revealed widened lateral joint space,
cupping of the lateral tibial plateau, Lateral joint space narrowing, squaring of the lateral
femoral condyle, cupping of the lateral tibial plateau, tibial eminence hypoplasia, and fibular
head elevation.3,4 MRI is widely used to diagnose the discoid meniscus. The most accurate
criteria for the diagnosis of discoid meniscus on MRI are a ratio of the minimal meniscal
width to maximal tibial width (on the coronal slice) of more than 20% and a ratio of the sum
of the width of both lateral horns to the meniscal diameter (on the sagittal slice showing the
maximal meniscal diameter) of more than 75%. Both ratios had a sensitivity and specificity
of 95% and 97%.3,4,5
Treatment of discoid meniscus depends on its type, concomitant symptom, duration of the
symptom and the patients‟ age. Tears of complete or incomplete discoid menisci that cause
pain and snapping within the knee and that show a hypermobile medial segment but intact
peripheral attachments are best treated by subtotal meniscectomy or a so-called saucerization
of the mobile fragment by arthroscopic techniques.2 The width of the remaining peripheral
rim is an important feature to consider when meniscectomy is performed. 3 The width of the
remaining peripheral rim should be between 5 mm and 8 mm to prevent instability of the
remnant, as such instability may cause a secondary meniscal tear.4 Wrisberg-type discoid
meniscus, treatment generally is total meniscectomy, either open or arthroscopic. Subtotal
meniscectomy alone leaves an unstable rim of meniscus that cause further problems.
Although total meniscectomy of a nondiscoid lateral meniscus may lead to progressive
osteoarthrosis in children and adults, children with discoid menisci seem less prone to these
degenerative changes.2 Many more recent studies have shown that total removal leads to a
high subsequent risk of degenerative osteoarthritis compared with partial meniscectomy with
preservation of a stable peripheral rim.4
CASE PRESENTATION
A 9-year-old female presented with a one-year history of knee pain in her right knee. She had
a history of trauma several years ago. The pain was aggravated by long distance walking,
5
walking on the stairs or bending the knee. Knee examination showed no deformity but a
limited range of motion of flexion and extension. The patient had lateral joint line tenderness.
A flexion-extension motion and McMurray test revealed a click sound on her right knee with
pain. On plain radiograph showed a flattening of tibial plateau and widening of joint space
on lateral tibial plateau. From advanced MRI showed an increasing ratio of the minimal
meniscal width to maximal tibial width on the coronal slice of more than 20% with a
meniscal tear.
6
Patient underwent an operation through arthroscopy with partial meniscectomy on her right
knee. Several days post operatively, patient trained to gain the motion of her knee by ROM
exercise. The patient returned to her activity, recovering full flexion and extension of the
knee and no limitations in activity daily living. Six months follow up post operative, patient
had no symptoms and showed a good result.
DISCUSSION
Discoid meniscus is an uncommon congenital condition of the knee. 1,3,4 Discoid meniscus
more common in Asian population with higher incidence in lateral meniscus. 3 The etiology
of discoid meniscus still unknown whereas there was many theory to describe this
phenomenon. Our case of discoid meniscus is complained by 9 years old girl who experience
pain on her knee for one year. The pain initially with history of trauma previously. On
physical examination we revealed joint tenderness and limitation of bending on the knee
while walking or squatting. For the purpose of confirming of her complaint we performed
conventional X-Ray examination. However, our case has abnormal radiographic findings that
related to the discoid meniscus. We found flattening of tibial plateau and widening of joint
space on lateral tibial plateau.
From MRI of the knee then we found increased ratio of the minimal meniscal width to
maximal tibial width on the coronal slice of more than 20%. In addition there is meniscal tear
on a lateral meniscus. This is predictor criteria of the discoid meniscus as on the previous
literature. The discoid shape of meniscus may probably make the meniscus susceptible to
minor injury. The discoid meniscus alone may be asymptomatic for this patient until those
structures was torn by injury. In our case, the pathological discoid meniscus is unilateral on
7
right knee. MRI of knee is consider the best predictor of radiological methods to confirmed
discoid meniscus especially on asymptomatic patient.3,4 After diagnose of discoid of
meniscus was confirmed, we educated her parent then suggested an operation to diminished
the complaint. Surgical treatment of discoid menisci should be considered only if the patient
is symptomatic.4,5 We performed the partial meniscectomy on her right knee with arthroscopy
procedure. We rebuild an anatomical shape of the meniscus.
We used WOMAC index to evaluate the functional outcome after the operation. We
take a questioner based on WOMAC Score at follow up. WOMAC index consist of three
item points: pain, joint stiffness, difficulty in physical activity.6 After the partial
meniscectomy patient followed up and examined with WOMAC Score. Patient can do
normal daily activity without pain and limitation of movement on her right knee. She can do
flexion and extension on her knee fully without pain and audible click sound. WOMAC
Score after partial meniscectomy the score was 8,3%. The score indicate there is no
significant pain, joint stiffness and difficulty on physical activity. After the operation patient
can do her normal daily activity, and there is no complained on her knee anymore. Partial
meniscectomy showed on excellent outcome for our case without presence another harmful
condition.
CONCLUSION
This study has shown that treatment of discoid meniscus with Partial Meniscectomy in
children is consider to get satisfactory functional outcome based on WOMAC index
8
REFERRENCE
1. Solomon L, Karachalios T. The Knee. Apley‟s System of Orthopaedics and Fracture
Ninth Edition. London 2010; 20: 561
2. Canaly, Beaty. Campbell‟s Operative Orthopaedics, 11 th ed. Philadelphia : Mosby
Elsevier, 2007
3. Yaniv M, Blumberg N. The Discoid Meniscus. J Child Orthop 2007; 1: 89-96
4. Ye Sun, Qing Jiang. Review of Discoid Meniscus. Orthopaedic Surgery. 2011;
3(4):219–223
5. Lee JH , Wang SI, Park JH, Lim YJ . A Case of Asymmetric Bilateral Discoid Medial
Menisci. J Korean Knee Soc 2011; 23(4): 55-60
6. Singh AP, WOMAC Index, Available from : :http://www.bonespine.com/womacindex (accesed 2015, 28 August)
9
MENISCUS
1
I Gusti Agung Gde Dendy
2
I G N Wien Aryana
1
Resident of Orthopaedic and Traumatology Department,
Sanglah General Hospital, Udayana University, Bali
2
Staff of Orthopaedic and Traumatology Department,
Sanglah General Hospital, Udayana University, Bali
BACKGROUND
Discoid meniscus is common congenital anatomical anomaly of the meniscus. A discoid
meniscus has abnormal morphology. It is thicker and covers more of the tibial plateau. The
cause of discoid meniscus is unknown, though there are some theories by Smillie and
Kaplan. Watanabe describe discoid meniscus as complete, incomplete, and Wrisberg type.
The physical examination usually showed pain, swelling, joint tenderness, effusion, limited
extension, and classic audible “snapping knee”. The most accurate criteria for the diagnosis
of discoid meniscus on radiograph is MRI. Surgical treatment necessary for those
symptomatic conditions by partial or total meniscectomy.
CASE PRESENTATION
A 9-year-old female presented with a one-year history of knee pain in her right knee.
Physical examination revealed a limited range of motion of flexion and extension also
audible click sound McMurray. On radiograph showed a flattening of tibial plateau and
widening of joint space with an increasing ratio of the minimal meniscal width to maximal
tibial width on the coronal slice of more than 20%. Patient undergone partial meniscectomy
and 6 months post operatively, patient showed a good result based on WOMAC index.
DISCUSSION
After the partial meniscectomy patient followed up and examined with WOMAC Score.
Patient can do normal daily activity without pain and limitation of movement on her right
knee. She can do flexion and extension on her knee fully without pain and audible click
1
sound. WOMAC Score after partial meniscectomy the score was 8,3 %. The score indicate
there is no significant pain, joint stiffness and difficulty on physical activity. After the
operation patient can do her normal daily activity, and there is no complained on her knee
anymore.
CONCLUSIONS
This study has shown that treatment of discoid meniscus with Partial Meniscectomy in
children is consider to get satisfactory functional outcome based on WOMAC index
Keyword :discoid meniscus, arthroscopy, partial meniscectomy,WOMAC index
2
BACKGROUND
Discoid meniscus, a common anatomical anomaly of the meniscus, was first described by
Young in 1889. In the fetus the meniscusis is disc-like; if this shape persists, symptoms are
likely.1 Discoid meniscus is an uncommon meniscal anomaly that occurs more frequently
laterally than medially.2 The normal menisci differentiate within the limb bud from
mesenchymal tissue early during fetal development. They gain mature anatomical shape at
the 14th week, without ever possessing a discoid shape. By 9 months of life, the central third
becomes avascular, and only the peripheral third retains its blood supply at adulthood. The
inner two-thirds receive nourishment via diffusion from the intra-articular fluid. In adults, the
C-shaped medial meniscus covers 50% of the medial tibial plateau and is connected firmly to
the joint capsule.3
A discoid meniscus has abnormal morphology. It is thicker and covers more of the tibial
plateau. The incidence of lateral discoid meniscus is 0.4% to 17%5, compared to 0.06% to
0.3%for the medial one. 20% of discoid lateral meniscus are bilateral, whereas bilateral
discoid medial meniscus is rare. The incidence is estimated to be 3% to 5% in the general
population and slightly higher in Asian populations The precise cause of discoid meniscus is
unknown, though there are some theories.3,4
Several theories describe the pathology of these anatomies. Smillie suggested that the
discoid shape is an intermediate stage during the fetal state, and that occurrence of the final
discoid morphology is caused by absorption failure of the central part of the menisci
(“congenital discoid meniscus”). Kaplan suggested that deficiency of the posterior meniscal
attachments causes meniscal hyper mobility, leading to a high incidence of repetitive
microtrauma that results in morphological changes. Kaplan‟s theory, however, makes no
3
sense in cases with normal posterior attachments. The congenital theory is supported by
reports of familial transmission and of the anomaly occurring in twins.3,4
Smillie first classified discoid meniscus into three types: the primitive type that affects the
whole disc, the intermediate type that is smaller and less complete, and the infantile type,
which differs in that the middle segment has greatly increased breadth. Watanabe et al
classified various types of lateral discoid meniscus based on its arthroscopic appearance and
on the basis of the degree of coverage of the lateral tibial plateau and the presence or absence
of the normal posterior meniscotibial attachment as; complete, incomplete, and Wrisberg
type.2 Discoid menisci with normal peripheral attachments were labeled as either type I
(complete) or type II (incomplete) according to the degree of coverage of the lateral tibial
plateau. Type III (also the Wrisberg ligament type) includes cases without normal posterior
meniscotibial attachment, thus allowing increased mobility and producing the classic
„„snapping knee‟‟ syndrome. Wrisberg-type discoid menisci often occur at a younger age
than complete or incomplete types and are unassociated with trauma. If an incomplete or
complete discoid meniscus is torn, symptoms are similar to those of any other meniscal tear:
lateral joint line tenderness, clicking, and effusion. 3,4
If there is only a clunk, treatment is not essential.1 Stable discoid meniscus, especially
an intact, complete or incomplete discoid meniscus usually seen as an incidental finding at
arthroscopy, does not necessarily require treatment until develop tears or degeneration within
the meniscus. Unstable discoid meniscus produces the classical „„snapping knee‟‟. It is
usually related to Wrisberg ligament type, but it can also be seen when a torn stable discoid
meniscus becomes unstable due to spread of a tear that includes the posterior tibial
4
attachment.3,4 On physical examination, the patient may present with pain, swelling, joint
line tenderness,
effusion, limited extension, and anterolateral bulge at full flexion.
McMurray test may be positive, but it is not typical especially in young children. A true
locking is a rare presentation; whereas pseudo-locking more often occur, but requires no
specific maneuver to restore range of motion.3,4
Conventional imaging radiograph usually revealed widened lateral joint space,
cupping of the lateral tibial plateau, Lateral joint space narrowing, squaring of the lateral
femoral condyle, cupping of the lateral tibial plateau, tibial eminence hypoplasia, and fibular
head elevation.3,4 MRI is widely used to diagnose the discoid meniscus. The most accurate
criteria for the diagnosis of discoid meniscus on MRI are a ratio of the minimal meniscal
width to maximal tibial width (on the coronal slice) of more than 20% and a ratio of the sum
of the width of both lateral horns to the meniscal diameter (on the sagittal slice showing the
maximal meniscal diameter) of more than 75%. Both ratios had a sensitivity and specificity
of 95% and 97%.3,4,5
Treatment of discoid meniscus depends on its type, concomitant symptom, duration of the
symptom and the patients‟ age. Tears of complete or incomplete discoid menisci that cause
pain and snapping within the knee and that show a hypermobile medial segment but intact
peripheral attachments are best treated by subtotal meniscectomy or a so-called saucerization
of the mobile fragment by arthroscopic techniques.2 The width of the remaining peripheral
rim is an important feature to consider when meniscectomy is performed. 3 The width of the
remaining peripheral rim should be between 5 mm and 8 mm to prevent instability of the
remnant, as such instability may cause a secondary meniscal tear.4 Wrisberg-type discoid
meniscus, treatment generally is total meniscectomy, either open or arthroscopic. Subtotal
meniscectomy alone leaves an unstable rim of meniscus that cause further problems.
Although total meniscectomy of a nondiscoid lateral meniscus may lead to progressive
osteoarthrosis in children and adults, children with discoid menisci seem less prone to these
degenerative changes.2 Many more recent studies have shown that total removal leads to a
high subsequent risk of degenerative osteoarthritis compared with partial meniscectomy with
preservation of a stable peripheral rim.4
CASE PRESENTATION
A 9-year-old female presented with a one-year history of knee pain in her right knee. She had
a history of trauma several years ago. The pain was aggravated by long distance walking,
5
walking on the stairs or bending the knee. Knee examination showed no deformity but a
limited range of motion of flexion and extension. The patient had lateral joint line tenderness.
A flexion-extension motion and McMurray test revealed a click sound on her right knee with
pain. On plain radiograph showed a flattening of tibial plateau and widening of joint space
on lateral tibial plateau. From advanced MRI showed an increasing ratio of the minimal
meniscal width to maximal tibial width on the coronal slice of more than 20% with a
meniscal tear.
6
Patient underwent an operation through arthroscopy with partial meniscectomy on her right
knee. Several days post operatively, patient trained to gain the motion of her knee by ROM
exercise. The patient returned to her activity, recovering full flexion and extension of the
knee and no limitations in activity daily living. Six months follow up post operative, patient
had no symptoms and showed a good result.
DISCUSSION
Discoid meniscus is an uncommon congenital condition of the knee. 1,3,4 Discoid meniscus
more common in Asian population with higher incidence in lateral meniscus. 3 The etiology
of discoid meniscus still unknown whereas there was many theory to describe this
phenomenon. Our case of discoid meniscus is complained by 9 years old girl who experience
pain on her knee for one year. The pain initially with history of trauma previously. On
physical examination we revealed joint tenderness and limitation of bending on the knee
while walking or squatting. For the purpose of confirming of her complaint we performed
conventional X-Ray examination. However, our case has abnormal radiographic findings that
related to the discoid meniscus. We found flattening of tibial plateau and widening of joint
space on lateral tibial plateau.
From MRI of the knee then we found increased ratio of the minimal meniscal width to
maximal tibial width on the coronal slice of more than 20%. In addition there is meniscal tear
on a lateral meniscus. This is predictor criteria of the discoid meniscus as on the previous
literature. The discoid shape of meniscus may probably make the meniscus susceptible to
minor injury. The discoid meniscus alone may be asymptomatic for this patient until those
structures was torn by injury. In our case, the pathological discoid meniscus is unilateral on
7
right knee. MRI of knee is consider the best predictor of radiological methods to confirmed
discoid meniscus especially on asymptomatic patient.3,4 After diagnose of discoid of
meniscus was confirmed, we educated her parent then suggested an operation to diminished
the complaint. Surgical treatment of discoid menisci should be considered only if the patient
is symptomatic.4,5 We performed the partial meniscectomy on her right knee with arthroscopy
procedure. We rebuild an anatomical shape of the meniscus.
We used WOMAC index to evaluate the functional outcome after the operation. We
take a questioner based on WOMAC Score at follow up. WOMAC index consist of three
item points: pain, joint stiffness, difficulty in physical activity.6 After the partial
meniscectomy patient followed up and examined with WOMAC Score. Patient can do
normal daily activity without pain and limitation of movement on her right knee. She can do
flexion and extension on her knee fully without pain and audible click sound. WOMAC
Score after partial meniscectomy the score was 8,3%. The score indicate there is no
significant pain, joint stiffness and difficulty on physical activity. After the operation patient
can do her normal daily activity, and there is no complained on her knee anymore. Partial
meniscectomy showed on excellent outcome for our case without presence another harmful
condition.
CONCLUSION
This study has shown that treatment of discoid meniscus with Partial Meniscectomy in
children is consider to get satisfactory functional outcome based on WOMAC index
8
REFERRENCE
1. Solomon L, Karachalios T. The Knee. Apley‟s System of Orthopaedics and Fracture
Ninth Edition. London 2010; 20: 561
2. Canaly, Beaty. Campbell‟s Operative Orthopaedics, 11 th ed. Philadelphia : Mosby
Elsevier, 2007
3. Yaniv M, Blumberg N. The Discoid Meniscus. J Child Orthop 2007; 1: 89-96
4. Ye Sun, Qing Jiang. Review of Discoid Meniscus. Orthopaedic Surgery. 2011;
3(4):219–223
5. Lee JH , Wang SI, Park JH, Lim YJ . A Case of Asymmetric Bilateral Discoid Medial
Menisci. J Korean Knee Soc 2011; 23(4): 55-60
6. Singh AP, WOMAC Index, Available from : :http://www.bonespine.com/womacindex (accesed 2015, 28 August)
9