Knee Surg Sports Traumatol Arthrosc DOI 10.1007/s00167-014-2939-z
KNEE
Medial meniscus tear morphology and related clinical symptoms in patients with medial knee osteoarthritis Masayuki Kamimura • Jutaro Umehara Atsushi Takahashi • Toshimi Aizawa • Eiji Itoi
•
Received: 11 September 2013 / Accepted: 8 March 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose The objective of this study was to examine the association between clinical symptoms and arthroscopic meniscal findings in patients with early to moderate medial knee osteoarthritis. Methods One hundred and four patients (110 knees) were selected from a group of 132 patients (140 knees) aged C50 years who underwent arthroscopic surgery for medial meniscal tears. Inclusion criteria were as follows: (a) medial knee osteoarthritis and (b) simple medial meniscal tears extending to C1/4 of the meniscal margin. Subjective symptoms, location and nature of the pain, as well as the physical findings observed during initial assessment were evaluated using a standardized assessment chart. The relationship between arthroscopic meniscal findings and clinical symptoms was then analysed. Results Isolated meniscal tears were classified into four types: radial tear of the middle segment; posterior root tear; horizontal tear of the posterior segment; and flap tear. The following symptoms were reported at significantly higher frequencies: pain on standing and a catching sensation in patients with flap tears; pain on walking and nocturnal pain on rolling over in bed in patients with radial tears of the middle segment; and popliteal pain in patients with posterior root tears.
M. Kamimura A. Takahashi (&) T. Aizawa E. Itoi Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi Prefecture 980-8574, Japan e-mail: [email protected] J. Umehara Department of Orthopaedic Surgery, Senboku Kumiai General Hospital, 1-30 Omagari-torimati, Daisen, Akita Prefecture 014-0027, Japan
Conclusions This study demonstrates a relationship between the type of medial meniscal tear and characteristic clinical symptoms reported by patients with medial knee osteoarthritis. These results suggest that clinical symptoms in patients with osteoarthritis of the knee may be caused by meniscal tears. This evidence may help to better inform patients and surgeons regarding choice of treatment. Level of evidence Case control study, Level III. Keywords Medial meniscal tears Medial knee osteoarthritis Clinical symptoms Meniscus tear morphology
Introduction Medial meniscal tears are often associated with medial knee osteoarthritis in elderly patients [2, 13]. Patients with a higher radiographic grade of osteoarthritis experience meniscal tears more frequently [2]. In general, tears of the meniscus are known to cause knee joint symptoms [8, 24, 29]. However, it is still controversial whether meniscal tears in patients with osteoarthritis cause knee joint symptoms. Several studies have demonstrated that meniscal tears are associated with clinical symptoms even in osteoarthritic patients, according to the effectiveness of arthroscopic meniscectomy [4, 7, 23]. On the other hand, other cohort studies have shown no significant relationship between meniscal damage and clinical symptoms reported by patients with osteoarthritis of the knee [2, 14]. Medial meniscal tears are classified into several types according to their tear pattern: longitudinal tear, radial tear, horizontal tear, and flap tear [6, 8, 24]. If osteoarthritic patients with medial meniscal tears exhibit distinct symptoms depending on the type of tears, this could support the
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Knee Surg Sports Traumatol Arthrosc
view that meniscal tears are associated with knee joint symptoms. Additionally, this information could help determine the origin of the symptoms and help decisions about appropriate treatment choices. We hypothesized that patients with early to moderate medial knee osteoarthritis who have medial meniscal tear have characteristic symptoms depending on the type of coexisting meniscal tear. To evaluate our hypothesis, we assessed the clinical symptoms of patients with medial knee osteoarthritis whose medial meniscal tear patterns had been confirmed arthroscopically.
Materials and methods One hundred and thirty-two patients (140 knees) aged C50 years underwent arthroscopic surgery for medial meniscal tears at Senboku Kumiai General Hospital over a 4-year period. Indications for surgery were medial knee pain, clear findings of medial meniscal tear on magnetic resonance imaging (MRI), and no resolution of symptoms with conservative treatment for at least 3 months. Patients diagnosed with grade 4 osteoarthritis by the Kellgren– Lawrence grading system for osteoarthritis classification [22] and those with clear bone marrow lesions [16] on MRI were treated with arthroplasty and did not undergo arthroscopic meniscectomy. Meniscal tears were classified arthroscopically, and tear patterns were confirmed by one of the authors using intraoperative images. The surgical intervention performed involved arthroscopic resection of unstable meniscal tears and chondral flaps. The same surgeon (JU) carried out all surgical procedures. One hundred and four patients (110 knees) met the following inclusion criteria for the study: (a) early to moderate medial knee osteoarthritis (defined as Kellgren–Lawrence grade of C1 using a standing posteroanterior radiograph) and (b) a simple medial meniscal tear (defined as a tear in just one plane) extending to 1/4 of the meniscal margins. The patients in this study included 76 females and 28 males, with an average age of 67 years. Twenty-eight patients (30 knees) were excluded due to following reasons: (a) seven knees were classified into Kellgren–Lawrence grade of 0, (b) 13 knees had complex tears, and (c) ten knees were determined to have tears not extending to 1/4 of the meniscal margin, in which the meniscal nerve distribution was confined [9]. Clinical evaluation Personal data of all patients including age, gender, body mass index (BMI), and the side of the operation were acquired from medical records. Subjects underwent weightbearing posteroanterior knee radiography just before the surgeries. Two orthopaedic surgeons graded all films according to Kellgen–Lawrernce scale [22]. Discrepancies
123
were adjudicated by a panel of two readers. The interrater reliability (kappa statistics) for determining Kellgen–Lawrernce grade was j = 0.64. No discrepancy of more than one grade was observed. During the study period, the subjective symptoms and objective physical findings of all patients aged C50 years whose chief complaint was medial knee pain were evaluated using a standardized assessment chart at their initial visit. Subjective symptoms included episodes of acute onset, catching sensations in the knee, popliteal pain, pain on standing, pain on walking, and nocturnal pain. Pain of acute onset was defined as an episode of pain in which the patient could identify the specific date of onset. Nocturnal pain was defined as a pain occurring in bed at night. Intense pain that patients experienced when rolling over in bed was recorded separately. Objective symptoms included medial joint space tenderness and the presence of joint effusion. Medial joint space tenderness was considered positive when the subject reported pain with digital palpation of a sufficient force to blanch the thumb nail. The relationship between the information from chart results and the type of medial meniscal tear determined by arthroscopy was statistically analysed. This study obtained approval from the ethics committee of Senboku Kumiai General Hospital (No. 78). Informed consent was obtained from all study participants. Statistical Analysis Statistical analysis was carried out using SPSS Statistics (version 18.0; IBM, Chicago, IL, USA). Age and BMI were compared among the groups having different types of meniscal tears using ANOVA. Kellgren–Lawrence grades were compared using the Kruskal–Wallis test. Gender and clinical symptoms were compared using Fisher’s exact test and residual analysis. Statistical significance was set at p \ 0.05.
Results Forty knees (36 %) were determined to be Kellgren– Lawrence grade 1, 49 knees (45 %) grade 2, and 21 knees (19 %) grade 3. Subjects were determined to have one of the following four types of medial meniscal tear: radial tear of the middle segment, 58 knees (53 %); posterior root tear, 29 knees (26 %); horizontal tear of the posterior segment, 15 knees (14 %); and flap tear, eight knees (7 %) (Fig. 1). Posterior root tears were identified as either meniscus detachments from its posterior insertion or radial tears near the posterior horn. Flap tears were defined as flap-like tears in the meniscus in which the longitudinal diameter of the tear was longer than the transverse diameter. All flap tears were observed at the middle or posterior
Knee Surg Sports Traumatol Arthrosc Fig. 1 Outline of each type of medial meniscal tear and arthroscopic findings. a Radial tear of the middle segment (type A). b Posterior root tear (type B). c Horizontal tear of the posterior segment (type C). d Flap tear of the middle or posterior segment (type D)
Table 1 Comparison of the backgrounds among the four types of meniscal tears Type A (n = 58)
Type B (n = 29)
Type C (n = 15)
Type D (n = 8)
Total (n = 110)
Probability (p)
Age (years)
68 ± 8
66 ± 8
68 ± 9
71 ± 6
67 ± 8
n.s.
Male/female
20/38*
2/27**
2/13
4/4
28/82
0.006a
Body mass index
25.5 ± 3.0
25.9 ± 3.4
24.7 ± 2.8
24.9 ± 1.3
25.5 ± 3.0
n.s.
Right/left
29/29
16/13
11/4
6/2
62/48
n.s.
Kellgren–Lawrence grade (1/2/3)
22/25/11
9/17/3
7/3/5
2/4/2
40/49/21
n.s.
* p \ 0.05; ** p \ 0.01 with residual analysis p \ 0.01 a
p values obtained from Fisher’s exact test
segment of the meniscus. No statistically significant differences in age, BMI, and Kellgren–Lawrence grade were detected among these four groups (Table 1). The incidence of posterior root tears was significantly higher in females than in males (p \ 0.01). Pain on standing and catching sensation were characteristic symptoms in patients with flap tears. In patients with radial tears of the middle segment, pain on walking and pain on rolling over were reported with significantly higher frequencies. Popliteal pain was observed more frequently in patients with posterior root tears than in patients with one of the other three types. Medial joint space tenderness was frequently observed in patients with radial tears of the middle segment and horizontal tears of the posterior segment (Table 2). Particularly, patients with radial tears of the middle segment occasionally complained of severe tenderness with grimace.
Discussion The most notable finding of the present study was the association between the morphology of medial meniscus
tears and characteristic clinical symptoms in patients with medial knee osteoarthritis. It is still controversial whether meniscal tears in patients with osteoarthritis cause knee joint symptoms [2, 6, 7, 10, 12]. Several studies in recent years fail to demonstrate the association between meniscal tears and clinical symptoms in such patients [2, 13, 14]. Englund et al. found no relationship between meniscal injuries demonstrated by MRI and subjective symptoms reported by patients with osteoarthritis [12]. By contrast, the same study observed an association between meniscal injuries and pain in subjects with no radiographic evidence of osteoarthritis. In this study, we focused on patients with medial knee osteoarthritis of Kellgren–Lawrence grade 1–3 in a standing position who had arthroscopic evidence of a medial meniscal tear. We were able to clearly demonstrate that these patients have characteristic symptoms depending on the classification of their medial meniscal tears. Therefore, the results of this study suggest that in patients with early to moderate knee osteoarthritis, medial meniscal tears may cause clinical symptoms by themselves. It is difficult to discriminate between symptoms caused by a meniscal tear and those of early-stage osteoarthritis of
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Knee Surg Sports Traumatol Arthrosc Table 2 Comparison of clinical symptoms among the four types of meniscal tears
Type A (n = 58)
Type B (n = 29)
Type C (n = 15)
Type D (n = 8)
Total (n = 110)
Probabilitya (p)
26
21
7
38
24
n.s.
Catching sensation
21
3*
0
63**
16
\0.001
Popliteal pain
9**
72**
27
25
29
\0.001
Pain on standing
59
48
27*
88*
54
0.028
Pain on walking
86**
45**
47
38
66
\0.001
Nocturnal pain Pain on rolling over
69 62**
76 35
67 27
25 13*
67 46
n.s. 0.003
Tenderness of the medial joint space
85**
31**
93*
63
70
\0.001
Joint effusion
36
52
40
75
44
n.s.
Acute onset (%) Subjective symptoms (%)
* p \ 0.05; ** p \ 0.01 with residual analysis
p \ 0.05; p \ 0.01 a p values obtained from Fisher’s exact test
Objective symptoms (%)
the knee [11]. In this study, the four types of meniscal tear—radial tear of the middle segment, posterior root tear, horizontal tear of the posterior segment, and flap tear of the middle or posterior segment—were associated with characteristic clinical symptoms. Therefore, the results of this study may have an important role in differentiating whether clinical symptoms in these patients originates from meniscal tears. Pain on walking, pain on rolling over, and tenderness of the medial joint space were characteristic symptoms of radial tears of the middle segment. Pena et al. [28] reported that maximum contact pressure during weight bearing took place at the middle segment. During walking or knee-twisting motion, mechanical stress is concentrated around the tear site, which might account for these clinical symptoms. Habata et al. [17] identified popliteal pain as a characteristic symptom in patients with posterior root tears of the medial meniscus, with pain and tenderness localized to the posterior region of the knee rather than the medial region. This study supports these earlier findings that popliteal pain was significantly related with a posterior root tear. As posterior root tears are occasionally difficult to diagnose using MRI, this type of tear is prone to being overlooked in clinical practice [3, 21]. Posterior root tears should be considered in the differential diagnosis when patients with mild to moderate medial osteoarthritis complain of popliteal pain. Zanetti et al. [33] analysed MRI of 100 symptomatic and 100 contralateral asymptomatic knees and concluded that horizontal tears may not cause subjective symptoms. However, in this study, 93 % of patients with horizontal tears demonstrated medial joint space tenderness. Although tenderness is frequently detected in patients with medial OA, horizontal tears may also be related with this objective finding. Horizontal tears of the posterior segment were designated as horizontal cleavages, which have previously been reported to be the most common tear pattern in the elderly
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[26]. By contrast, in this study, the incidence of horizontal tears was lower than that of radial tears of the middle segment or posterior root tears. The subjects included in this study had all undergone arthroscopic surgery. Patients with horizontal tears occasionally have no clinical symptoms [33]. This might therefore account for the reduced incidence of horizontal tears noted in this study. Posterior root tears have been reported to be a characteristic tear pattern in middle-aged and elderly patients [17, 20, 25, 27]. Furthermore, the incidence of this type of tear is thought to be considerably higher in women than in men [5, 27]. Similarly, in this study, the incidence of this type of tear was significantly higher in women. A high incidence of posterior root tears in women may partly explain why severe osteoarthritis is more common in women than in men. As posterior root tears cause a significant increase in contact pressure, which is comparable to that after total meniscectomy [1], it is highly related to the presence of bone marrow lesions [30, 32]. The degree to which arthroscopic meniscectomy benefits the management of osteoarthritis with meniscal tears is still highly debated [4, 7, 10, 15, 18, 19, 23, 31]. Bin et al. reported that partial resection was useful for treating meniscal tears in patients with grade 4 medial compartment osteoarthritis of the knee. In addition, Crevoisier et al. reported that partial resection of the medial meniscus was useful in patients aged C70 years. On the other hand, there are also reports negating the utility of partial meniscectomy in patients with osteoarthritis of the knee. The results of the present study suggest that patient symptoms vary depending upon the type of meniscal tear and imply that the utility of meniscectomy might also vary depending on the type of meniscal tear. However, the reports above did not distinguish the effectiveness of treatment according to the type of meniscal tear. Further studies focusing on the types of meniscal tear are required to evaluate the effectiveness of this treatment.
Knee Surg Sports Traumatol Arthrosc
There were clear limitations in this study. First, postoperative clinical symptoms were not assessed. Further prospective studies are required to determine the time course of the symptoms reported. Second, although we demonstrated that characteristic symptoms of meniscal tears were observed in patients with medial knee osteoarthritis, there is doubt as to what symptoms are specific to osteoarthritis alone. In addition, there are possible overlapping symptoms between osteoarthritis and meniscal tear. Third, selection bias might exist in this study as patients selected for this study consisted solely of arthroscopic surgical patients. Despite these limitations, this is the first study to clearly demonstrate the relationship between the type of medial meniscal tear and clinical symptoms reported by patients with early to moderate knee osteoarthritis. The results of this study would be useful for detecting whether clinical symptoms are caused by meniscal tears in osteoarthritic patients.
Conclusions Medial meniscal tear morphology appears to be associated with characteristic clinical symptoms: Pain on walking, pain on rolling over in bed, and medial joint space tenderness are the characteristic symptoms of a radial tear of the middle segment; popliteal pain is the characteristic symptom of a posterior root tear; medial joint space tenderness is the characteristic symptom of a horizontal tear of the posterior segment; and pain on standing and catching sensation are characteristic symptoms of a flap tear. Acknowledgments The authors would like to thank Dr. Karl Alvarez for his writing assistance.
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6. Christoforakis J, Pradhan R, Sanchez-Ballester J, Hunt N, Strachan RK (2005) Is there an association between articular cartilage changes and degenerative meniscus tears? Arthroscopy 21:1366–1369 7. Crevoisier X, Munzinger U, Drobny T (2001) Arthroscopic partial meniscectomy in patients over 70 years of age. Arthroscopy 17:732–736 8. Dandy DJ (1990) The arthroscopic anatomy of symptomatic meniscal lesions. J Bone Joint Surg Br 72:628–633 9. Day B, Mackenzie WG, Shim SS, Leung G (1985) The vascular and nerve supply of the human meniscus. Arthroscopy 1:58–62 10. Dervin GF, Stiell IG, Rody K, Grabowski J (2003) Effect of arthroscopic debridement for osteoarthritis of the knee on healthrelated quality of life. J Bone Joint Surg Am 85:10–19 11. Dervin GF, Stiell IG, Wells GA, Rody K, Grabowski J (2001) Physicians’ accuracy and interrator reliability for the diagnosis of unstable meniscal tears in patients having osteoarthritis of the knee. Can J Surg 44:267–274 12. Englund M, Guermazi A, Gale D, Hunter DJ, Aliabadi P, Clancy M, Felson DT (2008) Incidental meniscal findings on knee MRI in middle-aged and elderly persons. N Engl J Med 359:1108–1115 13. Englund M, Guermazi A, Roemer FW, Aliabadi P, Yang M, Lewis CE, Torner J, Nevitt MC, Sack B, Felson DT (2009) Meniscal tear in knees without surgery and the development of radiographic osteoarthritis among middle-aged and elderly persons: the Multicenter Osteoarthritis Study. Arthritis Rheum 60:831–839 14. Englund M, Niu J, Guermazi A, Roemer FW, Hunter DJ, Lynch JA, Lewis CE, Torner J, Nevitt MC, Zhang YQ, Felson DT (2007) Effect of meniscal damage on the development of frequent knee pain, aching, or stiffness. Arthritis Rheum 56:4048–4054 15. Englund M, Roos EM, Lohmander LS (2003) Impact of type of meniscal tear on radiographic and symptomatic knee osteoarthritis: a sixteen-year followup of meniscectomy with matched controls. Arthritis Rheum 48:2178–2187 16. Felson DT, Chaisson CE, Hill CL, Totterman SM, Gale ME, Skinner KM, Kazis L, Gale DR (2001) The association of bone marrow lesions with pain in knee osteoarthritis. Ann Intern Med 134:541–549 17. Habata T, Uematsu K, Hattori K, Takakura Y, Fujisawa Y (2004) Clinical features of the posterior horn tear in the medial meniscus. Arch Orthop Trauma Surg 124:642–645 18. Herrlin S, Hallander M, Wange P, Weidenhielm L, Werner S (2007) Arthroscopic or conservative treatment of degenerative medial meniscal tears: a prospective randomised trial. Knee Surg Sports Traumatol Arthrosc 15:393–401 19. Herrlin SV, Wange PO, Lapidus G, Hallander M, Werner S, Weidenhielm L (2013) Is arthroscopic surgery beneficial in treating non-traumatic, degenerative medial meniscal tears? a five year follow-up. Knee Surg Sports Traumatol Arthrosc 21:358–364 20. Hunter DJ, Zhang YQ, Niu JB, Tu X, Amin S, Clancy M, Guermazi A, Grigorian M, Gale D, Felson DT (2006) The association of meniscal pathologic changes with cartilage loss in symptomatic knee osteoarthritis. Arthritis Rheum 54:795–801 21. Jones AO, Houang MT, Low RS, Wood DG (2006) Medial meniscus posterior root attachment injury and degeneration: mRI findings. Australas Radiol 50:306–313 22. Kellgren J, Lawrenc J (1957) Radiological assessment of osteoarthritis. Ann Rheum Dis 16:494–501 23. Matsusue Y, Thomson NL (1996) Arthroscopic partial medial meniscectomy in patients over 40 years old: a 5- to 11-year follow-up study. Arthroscopy 12:39–44 24. Metcalf MH, Barrett GR (2004) Prospective evaluation of 1485 meniscal tear patterns in patients with stable knees. Am J Sports Med 32:675–680
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Knee Surg Sports Traumatol Arthrosc 25. Neogi DS, Kumar A, Rijal L, Yadav CS, Jaiman A, Nag HL (2013) Role of nonoperative treatment in managing degenerative tears of the medial meniscus posterior root. J Orthop Traumatol 14:193–199 26. Noble J, Hamblen DL (1975) The pathology of the degenerate meniscus lesion. J Bone Joint Surg Br 57:180–186 27. Ozkoc G, Circi E, Gonc U, Irgit K, Pourbagher A, Tandogan RN (2008) Radial tears in the root of the posterior horn of the medial meniscus. Knee Surg Sports Traumatol Arthrosc 16:849–854 28. Pena E, Calvo B, Martinez MA, Palanca D, Doblare M (2005) Finite element analysis of the effect of meniscal tears and meniscectomies on human knee biomechanics. Clin Biomech (Bristol, Avon) 20:498–507 29. Pujol N, Bohu Y, Boisrenoult P, Macdes A, Beaufils P (2013) Clinical outcomes of open meniscal repair of horizontal meniscal tears in young patients. Knee Surg Sports Traumatol Arthrosc 21:1530–1533
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30. Robertson DD, Armfield DR, Towers JD, Irrgang JJ, Maloney WJ, Harner CD (2009) Meniscal root injury and spontaneous osteonecrosis of the knee: an observation. J Bone Joint Surg Br 91:190–195 31. Roos EM, Ostenberg A, Roos H, Ekdahl C, Lohmander LS (2001) Long-term outcome of meniscectomy: symptoms, function, and performance tests in patients with or without radiographic osteoarthritis compared to matched controls. Osteoarthr Cartil 9:316–324 32. Yao L, Stanczak J, Boutin RD (2004) Presumptive subarticular stress reactions of the knee: MRI detection and association with meniscal tear patterns. Skelet Radiol 33:260–264 33. Zanetti M, Pfirrmann CW, Schmid MR, Romero J, Seifert B, Hodler J (2003) Patients with suspected meniscal tears: prevalence of abnormalities seen on MRI of 100 symptomatic and 100 contralateral asymptomatic knees. AJR Am J Roentgenol 181:635–641
KNEE
Medial meniscus tear morphology and related clinical symptoms in patients with medial knee osteoarthritis Masayuki Kamimura • Jutaro Umehara Atsushi Takahashi • Toshimi Aizawa • Eiji Itoi
•
Received: 11 September 2013 / Accepted: 8 March 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose The objective of this study was to examine the association between clinical symptoms and arthroscopic meniscal findings in patients with early to moderate medial knee osteoarthritis. Methods One hundred and four patients (110 knees) were selected from a group of 132 patients (140 knees) aged C50 years who underwent arthroscopic surgery for medial meniscal tears. Inclusion criteria were as follows: (a) medial knee osteoarthritis and (b) simple medial meniscal tears extending to C1/4 of the meniscal margin. Subjective symptoms, location and nature of the pain, as well as the physical findings observed during initial assessment were evaluated using a standardized assessment chart. The relationship between arthroscopic meniscal findings and clinical symptoms was then analysed. Results Isolated meniscal tears were classified into four types: radial tear of the middle segment; posterior root tear; horizontal tear of the posterior segment; and flap tear. The following symptoms were reported at significantly higher frequencies: pain on standing and a catching sensation in patients with flap tears; pain on walking and nocturnal pain on rolling over in bed in patients with radial tears of the middle segment; and popliteal pain in patients with posterior root tears.
M. Kamimura A. Takahashi (&) T. Aizawa E. Itoi Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi Prefecture 980-8574, Japan e-mail: [email protected] J. Umehara Department of Orthopaedic Surgery, Senboku Kumiai General Hospital, 1-30 Omagari-torimati, Daisen, Akita Prefecture 014-0027, Japan
Conclusions This study demonstrates a relationship between the type of medial meniscal tear and characteristic clinical symptoms reported by patients with medial knee osteoarthritis. These results suggest that clinical symptoms in patients with osteoarthritis of the knee may be caused by meniscal tears. This evidence may help to better inform patients and surgeons regarding choice of treatment. Level of evidence Case control study, Level III. Keywords Medial meniscal tears Medial knee osteoarthritis Clinical symptoms Meniscus tear morphology
Introduction Medial meniscal tears are often associated with medial knee osteoarthritis in elderly patients [2, 13]. Patients with a higher radiographic grade of osteoarthritis experience meniscal tears more frequently [2]. In general, tears of the meniscus are known to cause knee joint symptoms [8, 24, 29]. However, it is still controversial whether meniscal tears in patients with osteoarthritis cause knee joint symptoms. Several studies have demonstrated that meniscal tears are associated with clinical symptoms even in osteoarthritic patients, according to the effectiveness of arthroscopic meniscectomy [4, 7, 23]. On the other hand, other cohort studies have shown no significant relationship between meniscal damage and clinical symptoms reported by patients with osteoarthritis of the knee [2, 14]. Medial meniscal tears are classified into several types according to their tear pattern: longitudinal tear, radial tear, horizontal tear, and flap tear [6, 8, 24]. If osteoarthritic patients with medial meniscal tears exhibit distinct symptoms depending on the type of tears, this could support the
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Knee Surg Sports Traumatol Arthrosc
view that meniscal tears are associated with knee joint symptoms. Additionally, this information could help determine the origin of the symptoms and help decisions about appropriate treatment choices. We hypothesized that patients with early to moderate medial knee osteoarthritis who have medial meniscal tear have characteristic symptoms depending on the type of coexisting meniscal tear. To evaluate our hypothesis, we assessed the clinical symptoms of patients with medial knee osteoarthritis whose medial meniscal tear patterns had been confirmed arthroscopically.
Materials and methods One hundred and thirty-two patients (140 knees) aged C50 years underwent arthroscopic surgery for medial meniscal tears at Senboku Kumiai General Hospital over a 4-year period. Indications for surgery were medial knee pain, clear findings of medial meniscal tear on magnetic resonance imaging (MRI), and no resolution of symptoms with conservative treatment for at least 3 months. Patients diagnosed with grade 4 osteoarthritis by the Kellgren– Lawrence grading system for osteoarthritis classification [22] and those with clear bone marrow lesions [16] on MRI were treated with arthroplasty and did not undergo arthroscopic meniscectomy. Meniscal tears were classified arthroscopically, and tear patterns were confirmed by one of the authors using intraoperative images. The surgical intervention performed involved arthroscopic resection of unstable meniscal tears and chondral flaps. The same surgeon (JU) carried out all surgical procedures. One hundred and four patients (110 knees) met the following inclusion criteria for the study: (a) early to moderate medial knee osteoarthritis (defined as Kellgren–Lawrence grade of C1 using a standing posteroanterior radiograph) and (b) a simple medial meniscal tear (defined as a tear in just one plane) extending to 1/4 of the meniscal margins. The patients in this study included 76 females and 28 males, with an average age of 67 years. Twenty-eight patients (30 knees) were excluded due to following reasons: (a) seven knees were classified into Kellgren–Lawrence grade of 0, (b) 13 knees had complex tears, and (c) ten knees were determined to have tears not extending to 1/4 of the meniscal margin, in which the meniscal nerve distribution was confined [9]. Clinical evaluation Personal data of all patients including age, gender, body mass index (BMI), and the side of the operation were acquired from medical records. Subjects underwent weightbearing posteroanterior knee radiography just before the surgeries. Two orthopaedic surgeons graded all films according to Kellgen–Lawrernce scale [22]. Discrepancies
123
were adjudicated by a panel of two readers. The interrater reliability (kappa statistics) for determining Kellgen–Lawrernce grade was j = 0.64. No discrepancy of more than one grade was observed. During the study period, the subjective symptoms and objective physical findings of all patients aged C50 years whose chief complaint was medial knee pain were evaluated using a standardized assessment chart at their initial visit. Subjective symptoms included episodes of acute onset, catching sensations in the knee, popliteal pain, pain on standing, pain on walking, and nocturnal pain. Pain of acute onset was defined as an episode of pain in which the patient could identify the specific date of onset. Nocturnal pain was defined as a pain occurring in bed at night. Intense pain that patients experienced when rolling over in bed was recorded separately. Objective symptoms included medial joint space tenderness and the presence of joint effusion. Medial joint space tenderness was considered positive when the subject reported pain with digital palpation of a sufficient force to blanch the thumb nail. The relationship between the information from chart results and the type of medial meniscal tear determined by arthroscopy was statistically analysed. This study obtained approval from the ethics committee of Senboku Kumiai General Hospital (No. 78). Informed consent was obtained from all study participants. Statistical Analysis Statistical analysis was carried out using SPSS Statistics (version 18.0; IBM, Chicago, IL, USA). Age and BMI were compared among the groups having different types of meniscal tears using ANOVA. Kellgren–Lawrence grades were compared using the Kruskal–Wallis test. Gender and clinical symptoms were compared using Fisher’s exact test and residual analysis. Statistical significance was set at p \ 0.05.
Results Forty knees (36 %) were determined to be Kellgren– Lawrence grade 1, 49 knees (45 %) grade 2, and 21 knees (19 %) grade 3. Subjects were determined to have one of the following four types of medial meniscal tear: radial tear of the middle segment, 58 knees (53 %); posterior root tear, 29 knees (26 %); horizontal tear of the posterior segment, 15 knees (14 %); and flap tear, eight knees (7 %) (Fig. 1). Posterior root tears were identified as either meniscus detachments from its posterior insertion or radial tears near the posterior horn. Flap tears were defined as flap-like tears in the meniscus in which the longitudinal diameter of the tear was longer than the transverse diameter. All flap tears were observed at the middle or posterior
Knee Surg Sports Traumatol Arthrosc Fig. 1 Outline of each type of medial meniscal tear and arthroscopic findings. a Radial tear of the middle segment (type A). b Posterior root tear (type B). c Horizontal tear of the posterior segment (type C). d Flap tear of the middle or posterior segment (type D)
Table 1 Comparison of the backgrounds among the four types of meniscal tears Type A (n = 58)
Type B (n = 29)
Type C (n = 15)
Type D (n = 8)
Total (n = 110)
Probability (p)
Age (years)
68 ± 8
66 ± 8
68 ± 9
71 ± 6
67 ± 8
n.s.
Male/female
20/38*
2/27**
2/13
4/4
28/82
0.006a
Body mass index
25.5 ± 3.0
25.9 ± 3.4
24.7 ± 2.8
24.9 ± 1.3
25.5 ± 3.0
n.s.
Right/left
29/29
16/13
11/4
6/2
62/48
n.s.
Kellgren–Lawrence grade (1/2/3)
22/25/11
9/17/3
7/3/5
2/4/2
40/49/21
n.s.
* p \ 0.05; ** p \ 0.01 with residual analysis p \ 0.01 a
p values obtained from Fisher’s exact test
segment of the meniscus. No statistically significant differences in age, BMI, and Kellgren–Lawrence grade were detected among these four groups (Table 1). The incidence of posterior root tears was significantly higher in females than in males (p \ 0.01). Pain on standing and catching sensation were characteristic symptoms in patients with flap tears. In patients with radial tears of the middle segment, pain on walking and pain on rolling over were reported with significantly higher frequencies. Popliteal pain was observed more frequently in patients with posterior root tears than in patients with one of the other three types. Medial joint space tenderness was frequently observed in patients with radial tears of the middle segment and horizontal tears of the posterior segment (Table 2). Particularly, patients with radial tears of the middle segment occasionally complained of severe tenderness with grimace.
Discussion The most notable finding of the present study was the association between the morphology of medial meniscus
tears and characteristic clinical symptoms in patients with medial knee osteoarthritis. It is still controversial whether meniscal tears in patients with osteoarthritis cause knee joint symptoms [2, 6, 7, 10, 12]. Several studies in recent years fail to demonstrate the association between meniscal tears and clinical symptoms in such patients [2, 13, 14]. Englund et al. found no relationship between meniscal injuries demonstrated by MRI and subjective symptoms reported by patients with osteoarthritis [12]. By contrast, the same study observed an association between meniscal injuries and pain in subjects with no radiographic evidence of osteoarthritis. In this study, we focused on patients with medial knee osteoarthritis of Kellgren–Lawrence grade 1–3 in a standing position who had arthroscopic evidence of a medial meniscal tear. We were able to clearly demonstrate that these patients have characteristic symptoms depending on the classification of their medial meniscal tears. Therefore, the results of this study suggest that in patients with early to moderate knee osteoarthritis, medial meniscal tears may cause clinical symptoms by themselves. It is difficult to discriminate between symptoms caused by a meniscal tear and those of early-stage osteoarthritis of
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Knee Surg Sports Traumatol Arthrosc Table 2 Comparison of clinical symptoms among the four types of meniscal tears
Type A (n = 58)
Type B (n = 29)
Type C (n = 15)
Type D (n = 8)
Total (n = 110)
Probabilitya (p)
26
21
7
38
24
n.s.
Catching sensation
21
3*
0
63**
16
\0.001
Popliteal pain
9**
72**
27
25
29
\0.001
Pain on standing
59
48
27*
88*
54
0.028
Pain on walking
86**
45**
47
38
66
\0.001
Nocturnal pain Pain on rolling over
69 62**
76 35
67 27
25 13*
67 46
n.s. 0.003
Tenderness of the medial joint space
85**
31**
93*
63
70
\0.001
Joint effusion
36
52
40
75
44
n.s.
Acute onset (%) Subjective symptoms (%)
* p \ 0.05; ** p \ 0.01 with residual analysis
p \ 0.05; p \ 0.01 a p values obtained from Fisher’s exact test
Objective symptoms (%)
the knee [11]. In this study, the four types of meniscal tear—radial tear of the middle segment, posterior root tear, horizontal tear of the posterior segment, and flap tear of the middle or posterior segment—were associated with characteristic clinical symptoms. Therefore, the results of this study may have an important role in differentiating whether clinical symptoms in these patients originates from meniscal tears. Pain on walking, pain on rolling over, and tenderness of the medial joint space were characteristic symptoms of radial tears of the middle segment. Pena et al. [28] reported that maximum contact pressure during weight bearing took place at the middle segment. During walking or knee-twisting motion, mechanical stress is concentrated around the tear site, which might account for these clinical symptoms. Habata et al. [17] identified popliteal pain as a characteristic symptom in patients with posterior root tears of the medial meniscus, with pain and tenderness localized to the posterior region of the knee rather than the medial region. This study supports these earlier findings that popliteal pain was significantly related with a posterior root tear. As posterior root tears are occasionally difficult to diagnose using MRI, this type of tear is prone to being overlooked in clinical practice [3, 21]. Posterior root tears should be considered in the differential diagnosis when patients with mild to moderate medial osteoarthritis complain of popliteal pain. Zanetti et al. [33] analysed MRI of 100 symptomatic and 100 contralateral asymptomatic knees and concluded that horizontal tears may not cause subjective symptoms. However, in this study, 93 % of patients with horizontal tears demonstrated medial joint space tenderness. Although tenderness is frequently detected in patients with medial OA, horizontal tears may also be related with this objective finding. Horizontal tears of the posterior segment were designated as horizontal cleavages, which have previously been reported to be the most common tear pattern in the elderly
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[26]. By contrast, in this study, the incidence of horizontal tears was lower than that of radial tears of the middle segment or posterior root tears. The subjects included in this study had all undergone arthroscopic surgery. Patients with horizontal tears occasionally have no clinical symptoms [33]. This might therefore account for the reduced incidence of horizontal tears noted in this study. Posterior root tears have been reported to be a characteristic tear pattern in middle-aged and elderly patients [17, 20, 25, 27]. Furthermore, the incidence of this type of tear is thought to be considerably higher in women than in men [5, 27]. Similarly, in this study, the incidence of this type of tear was significantly higher in women. A high incidence of posterior root tears in women may partly explain why severe osteoarthritis is more common in women than in men. As posterior root tears cause a significant increase in contact pressure, which is comparable to that after total meniscectomy [1], it is highly related to the presence of bone marrow lesions [30, 32]. The degree to which arthroscopic meniscectomy benefits the management of osteoarthritis with meniscal tears is still highly debated [4, 7, 10, 15, 18, 19, 23, 31]. Bin et al. reported that partial resection was useful for treating meniscal tears in patients with grade 4 medial compartment osteoarthritis of the knee. In addition, Crevoisier et al. reported that partial resection of the medial meniscus was useful in patients aged C70 years. On the other hand, there are also reports negating the utility of partial meniscectomy in patients with osteoarthritis of the knee. The results of the present study suggest that patient symptoms vary depending upon the type of meniscal tear and imply that the utility of meniscectomy might also vary depending on the type of meniscal tear. However, the reports above did not distinguish the effectiveness of treatment according to the type of meniscal tear. Further studies focusing on the types of meniscal tear are required to evaluate the effectiveness of this treatment.
Knee Surg Sports Traumatol Arthrosc
There were clear limitations in this study. First, postoperative clinical symptoms were not assessed. Further prospective studies are required to determine the time course of the symptoms reported. Second, although we demonstrated that characteristic symptoms of meniscal tears were observed in patients with medial knee osteoarthritis, there is doubt as to what symptoms are specific to osteoarthritis alone. In addition, there are possible overlapping symptoms between osteoarthritis and meniscal tear. Third, selection bias might exist in this study as patients selected for this study consisted solely of arthroscopic surgical patients. Despite these limitations, this is the first study to clearly demonstrate the relationship between the type of medial meniscal tear and clinical symptoms reported by patients with early to moderate knee osteoarthritis. The results of this study would be useful for detecting whether clinical symptoms are caused by meniscal tears in osteoarthritic patients.
Conclusions Medial meniscal tear morphology appears to be associated with characteristic clinical symptoms: Pain on walking, pain on rolling over in bed, and medial joint space tenderness are the characteristic symptoms of a radial tear of the middle segment; popliteal pain is the characteristic symptom of a posterior root tear; medial joint space tenderness is the characteristic symptom of a horizontal tear of the posterior segment; and pain on standing and catching sensation are characteristic symptoms of a flap tear. Acknowledgments The authors would like to thank Dr. Karl Alvarez for his writing assistance.
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