December issue.indd

*Department of Orthopaedics, Glanfield Hospital, Leicester, U.K. Department of Orthopaedics, Lincoln County Hospital, Lincoln, U.K.

Correspondence to: M.C. Forster, 9 Lambourne Avenue, Ashbourne, Derbyshire, DE6 1BP

Introduction

Although the first meniscal repair was performed over 100 years ago, many aspects of meniscal repair remain controversial. This article reviews the structure and function of the menisci, the rationale for repair and the clinical results of arthroscopic meniscal repair

INTRODUCTION
Meniscal repair is not new. The first open meniscal repair was performed over 100 years ago and the first arthroscopic repairs were performed in 1969, prior to the use of fibreoptic cable and video screens.^7,8 Over the last 10 years, arthroscopic meniscal repair has been growing in popularity but despite many advances in equipment and techniques, it remains a difficult procedure and one that is possibly under-used in the UK. Many aspects of meniscal surgery remain controversial and many questions remain unanswered.

WHAT DOES THE MENISCUS DO?
An appreciation of meniscal structure and its relation to function is useful for an understanding of the role of the meniscus, meniscal tear patterns and the potential for repair.

The primary function of the meniscus is to protect articular cartilage from damage. It does this in two ways. Firstly, the menisci are made from fibrocartilage. This is reversibly deformable and acts as a shock absorber converting axial load into radial strain.³ Fifty per cent of the load is distributed this way during extension and up to 85% whilst weight bearing in flexion.⁴ This is particularly marked in the posterior horns. Secondly, the meniscus conforms to both the femur and tibia. This increase in joint conformity and surface area spreads the load over a larger area and decreases contact stresses between the femur and tibia. Additional benefits include prevention of soft tissue impingement and the secondary stabiliser effect of the posterior horn of the medial meniscus to anterior subluxation.^5,6

The C shaped menisci are made up of longitudinal fibres running in parallel around the C and radial tie fibres running across the C. The longitudinal fibres predominate at the periphery and these are stabilised by the radial fibres that weave around the longitudinal fibres to resist longitudinal splitting.^7,8 When the load placed on the meniscus is excessive, instead of converting the axial load to a radial strain, it tears. If the load is axial, the tear appears between the longitudinal fibres causing a longitudinal tear. With shear stresses, radial or horizontal tears can form by causing tears horizontally or vertically between the radial fibres.⁹ Flap tears and complex tears may be caused by a combination of forces.

The blood supply comes from the peripheral attachment and varies with age. During prenatal development, the majority of the meniscus is vascular but with increasing age, this recedes.¹⁰

In the adult, the vascular supply of the meniscus can be divided into three zones (roughly thirds).¹¹ The peripheral third or red/red zone has a good blood supply. The central third or white/white zone is avascular. The middle third or red/white zone has a variable blood supply. The vascularity of a meniscal tear obviously has a profound influence on whether or not it will heal if repaired.

WHY SHOULD TEARS BE REPAIRED?
The importance of the meniscus was highlighted by King’s (1936) seminal research.^12,13 Using a canine model, he found that the amount of degenerative change after meniscectomy was related to the amount of meniscus removed. Also, if artificial tears extended into the vascularised part of the meniscus, healing could occur. Following this, Fairbank (1948) observed degenerative radiological changes after meniscectomy.¹⁴ Since then, there have been many publications that confirm these changes even after the less radical partial meniscectomy.^15-21 Ten to 15 years after an arthroscopic partial medial meniscectomy,the operated knee is 16-33% more likely to have degenerate radiological changes, compared with the control knee.^19-21 This risk is increased in children and if there is chondral damage diagnosed during the arthroscopy.^22,23

Following meniscectomy any axial load is distributed over a smaller surface area (reduced by 33-50%) leading to increased contact stress (x 2-3).²⁴ This is the presumed mechanism for the increase in degenerative changes. Meniscal repair is performed with the aim of reducing these degenerative changes.

WHY DON’T WE REPAIR MORE OFTEN?
Meniscal repair is a difficult, time-consuming technique that requires special training and equipment. Most meniscal tears are diagnosed at day case arthroscopy and unless the equipment and expertise are available and, appropriate time for the case has been allocated, many potentially repairable tears may be excised instead. Having said this, many tears are not suitable for repair.

WHICH TEARS SHOULD BE REPAIRED?
Stable, peripheral tears in the red/red zone which displace <3mm, and are either full thickness and <5mm or partial thickness and <10mm, do not require repair or resection as they are likely to heal.²⁵

Longitudinal tears in the red/red or red/white zones in either meniscus should heal provided adequate stability is achieved (Figure 1).²⁶ Tears in the avascular white/white zone are unlikely to heal with repair alone. Radial and flap tears are generally unsuitable as they extend into the avascular zone, although some enthusiasts do repair these with some success.^27,28

Larger tears have been found to have less successful results when fibrin glue alone has been used but not with sutures or implants.^29-31

Whether the age of the tear influences healing repair is controversial. It seems logical that acute tears should heal more reliably due to the presence of inflammation and some evidence supports this.³² Other investigators have found no correlation between chronicity and healing rate.^33,34 However, chronic tears are less likely to be repairable due to degeneration and secondary tears.

The age of the patient has not been found to influence meniscal healing rates.^28,35 Again, with increasing age fewer tears are likely to be repairable due to degeneration of the meniscus.

Meniscal repair can be successful irrespective of the size of the tear, the age of the tear, the age of the patient and the presence or absence of an intact anterior cruciate ligamen (ACL). The decision on whether or not to repair a meniscal tear is usually made on the type and location of the tear and patient factors such as level of activity.

MENISCAL REPAIR IN ASSOCIATION WITH LIGAMENT DEFICIENCY AND RECONSTRUCTION
Meniscal repair in the ACL deficient knee results in poorer results, unless an ACL reconstruction is carried out at the same time.²⁶ This is likely to be related to the role of the meniscus as a secondary stabiliser. Interestingly, synchronous ACL reconstruction and meniscal repair results in a better outcome than isolated meniscal repair in ACL stable knees.³⁶ There is some evidence that the tears in ACL intact and ACL deficient knees are different. Meniscal tears in ACL deficient knees are less likely to be degenerative and may heal better as a result.

Figure 1: The magnetic resonance imaging (MRI) shows a peripheral meniscal tear without displacement or degeneration. This tear may be suitable for meniscal repair

Figure 4: An arthroscopic view of out to in suture insertion (courtesy of Mr S.P. Godsiff)

In addition, the haemarthrosis following ACL reconstruction is thought to provide serum factors that aid meniscal healing. The lax ACL deficient knee may also make meniscal repair easier. The results of meniscal repair in patients with other ligamental deficiencies are not known.

TECHNIQUES
There are many different arthroscopic techniques that can be divided into three main groups: inside-out; outside in and all inside. These descriptions refer to the placement of the stabilising suture or device, i.e. inside-out means the needle goes from inside the knee to outside the knee, etc. To ensure safe passage of needles from inside to out or outside to in, a posteromedial or posterolateral incision is usually used.

Using either inside-out or outside-in techniques, vertical or horizontal mattress sutures are used to repair the meniscal tear (Figures 2 to 4). Whether the suture should be absorbable or nonabsorbable remains controversial.²⁶

All inside techniques usually use biodegradable devices to appose the meniscal tear (Figures 5 and 6). One attraction to these implants is that they can be inserted without any additional incisions and the risk of iatrogenic neurovascular damage is very low.

PREPARATION
Preparation of the meniscus prior to repair is important. The torn surfaces of the meniscus should be abraded, as should the synovium superior and inferior to the tear. This aims to increase vascularity and it improves repair rates.³⁷ Fibrin clot may be used in addition to further improve vascularity.³⁸

HOW STRONG ARE THE REPAIRS?
Biomechanical testing has been performed on human, bovine and porcine menisci, both fresh and frozen.^39-44 Vertical mattress suturing techniques are consistently the strongest. Horizontal sutures have around 50-75% of the strength but the strength of the various implants is less consistent. Some are of similar strength to horizontal suturing (Biofix meniscal arrow, T fix, Biostinger), some are considerably weaker. However, it is not known how strong a meniscal repair needs to be in order to heal.

DO THE MENISCI HEAL?
Some, but not all, meniscal repairs heal and some heal incompletely. There have been follow-up studies for inside-out, outside-in and some all inside techniques (T fix, Biofix, Fibrin glue).^{29,31,36,45-53} Many of the implants available have no studies to support their use. Studies that report clinical assessments have higher ‘healing rates’ than those using second look arthroscopy. Interestingly, only around 50% of unhealed tears can be predicted prior to arthroscopy.⁵³

Taking all series, 81-95% have a clinically acceptable outcome but only 23-73% are completely healed on arthroscopy.The lowest figures are for isolated tears in stable knees and the highest figures are with synchronous ACL reconstruction. Many other tears heal incompletely (17-37%) or do not heal (7-50%). Most of the studies have short follow-up (less than two years) and because of different indications for repair and different patient populations (e.g. with or without ACL reconstruction), comparison between the various series is difficult. Enthusiasts performed these studies and it remains uncertain whether the occasional meniscal repairer can repeat these results.

COMPLICATIONS
Specific complications include saphenous neuropathy (7%), arthrofibrosis (6%), septic arthritis (1%) and peroneal neuropathy (1%).⁵⁴ Implants have been associated with breakage, cyst formation, chondral damage and transient posterior knee pain.^55-60

DOES REPAIR PREVENT ARTICULAR CARTILAGE DAMAGE?
This is the rationale for repair. If arthroscopic meniscal repair does not prevent articular cartilage damage then the easier partial meniscectomy would be preferable. The only longterm follow-up study showed that 8% of knees show early degenerative changes, compared with 3% in the control knee.⁶¹ This compares well with the 16-33% following arthroscopic partial meniscectomy and underpins the indications for meniscal repair.^19-21

CONCLUSION
There is some evidence that arthroscopic meniscal repair may prevent the early degenerative changes associated with meniscectomy and should be considered for suitable tears, particularly in the younger patient. Suture techniques remain the ‘gold standard’ but the newer biodegradable implants may prove easier to use. It remains to be seen whether this is a technique that the occasional user will be able to use with predictable results.

REFERENCES
1. Annandale T. An operation for the displaced semilunar cartilage. Br Med J 1885; 1: 779.
2. Ikeuchi H. Arthroscopic peripheral meniscus repair. Sports Med Arthrosc Rev 1993; 1: 103.
3. Shrive NG, O’Connor JJ, Goodfellow JW. Loadbearing in the knee joint. Clin Orth 1978; 131: 279.
4. Dehaven DE, Arnoczky SP. Meniscal repair. J Bone Joint Surg [Am] 1994; 76A: 140.
5. Levy IM, Torzilli PA, Warren RF. The effect of medial meniscectomy on anterior-posterior motion of the knee. J Bone Joint Surg [Am] 1982; 64A: 883.
6. Sullivan D, Levy IM, Sheskier S et al. Medial restraints to anterior-posterior motion of the knee. J Bone Joint Surg [Am] 1984; 66A: 930.
7. Bullough PG, Manuera L, Murphy J et al. The strength of the menisci of the knee as it relates to their fine structures. J Bone Joint Surg [Br] 1970; 52B: 564.
8. Keene GCR, Bickerstaff D, Rae PJ et al. The natural history of meniscal tears in ACL insufficiency. Am J Sport Med 1993; 21: 672.
9. Ferrer-Roca O, Vilalta C. Lesions of the meniscus. Part I: Macroscopic and histologic findings. Clin Orth 1980; 146: 289.
10. Clark CR, Ogden JA. Development of the human knee joint. J Bone Joint Surg 1983; 65A: 538.
11. Arnoczky SP, Warren RF. The microvasculature of the human meniscus. Am J Sport Med 1982; 10: 90.
12. King D. The healing of semilunar cartilages. J Bone Joint Surg 1936; 18: 333.
13. King D. The function of semilunar cartilages. J Bone Joint Surg 1936; 18: 1069.
14. Fairbank TJ. Knee joint changes after meniscectomy. J Bone Joint Surg 1948; 30: 664.
15. Matsusue Y, Thompson NL. Arthroscopic partial meniscectomy in patients over 40 years old: a 5- to 11- year follow-up study. Arthroscopy 1996; 12: 39.
16. Burks RT, Metcalf MH, Metcalf RW. 15- year follow up of arthroscopic partial meniscectomy. Arthroscopy 1997; 13: 673.
17. Schimmer RC, Brulhart KB, Duff C et al. Arthroscopic partial meniscectomy: a 12-year follow-up and two-step evaluation of the long term course. Arthroscopy 1998; 14: 136.
18. Maletius W, Messner K. The effect of partial meniscectomy on the long-term prognosis of knees with localized, severe chondral damage. Am J Sport Med 1996; 24: 258.
19. Kruger-Franke M, Siebert CH, Kugler A et al. Late results after arthroscopic partial medial meniscectomy. Knee Surg, Sports Traumatol, Arthrosc 1999; 7: 81.
20. Chatain F, Robinson AHN, Adeleine P et al. The natural history of the knee following arthroscopic medial meniscectomy. Knee Surg, Sports Traumatol, Arthrosc 2001; 9: 15.
21. Hulet CH, Locker BG, Schiltz D et al. Arthroscopic medial meniscectomy on stable knees. J Bone Joint Surg [Br] 2001; 83B: 29.
22. Dai L, Zhang W, Xu Y. Meniscal injury in children: long-term results after meniscectomy. Knee Surg, Sports Traumatol, Arthrosc 1997; 5: 77.
23. Maletius W, Messner K. Chondral damage and age depress the long term prognosis after partial meniscectomy. Knee Surg, Sports Traumatol, Arthrosc 1996; 3: 211.
24. Kurosawa H, Fukubayashi T, Nakajima H. Loadbearing mode of the knee joint. Clin Orth 1980; 144: 283.
25. Weiss CB, Lundberg M, Hamberg P et al. Non-operative treatment of meniscal tear. J Bone Joint Surg [Am] 1989; 71A: 811.
26. Newman AP, Daniels AU, Burks RT. Principles and decision making in meniscal surgery. Arthroscopy 1993; 9: 33.
27. Rubman MH, Noyes FR, Barber-Westin SD. Arthroscopic repair of meniscal tears that extend into the avascular zone. Am J Sport Med 1998; 26: 87.
28. Noyes FR, Barber-Westin SD. Arthroscopic repair of meniscus tears extending into the avascular zone with or without ACL reconstruction in patients 40 years of age and older. Arthroscopy 2000; 16: 822.
29. Ishimura M, Ohgushi H, Habata T et al. Arthroscopic meniscal repair using fibrin glue. Arthroscopy 1997; 13: 558.
30. Tenuta JJ, Arciero RA. Arthroscopic evaluation of meniscal repairs. Am J Sport Med 1994; 22: 797.
31. Barrett GR, Treacy SH, Ruff CG. Preliminary results of the Tfix endoscopic meniscus repair technique in an ACL reconstruction population. Arthroscopy 1997; 13: 218.
32. Stone RG, Frewin PR, Gonzales S. Long-term assessment of arthroscopic meniscus repair. Arthroscopy 1990; 6: 73.
33. Buseck MS, Noyes FR. Arthroscopic evaluation of meniscal repairs after ACL reconstruction and immediate motion. Am J Sport Med 1991; 19:489.
34. Scott GA, Jolly BL, Henning CE. Combined posterior incision and arthroscopic intra-articular repair of the meniscus. J Bone Joint Surg [Am] 1986; 68A: 847.
35. Barrett GR, Field MH, Treacy SH et al. Clinical results of meniscus repair in patients 40 years and older. Arthroscopy 1998; 14: 824.
36. Cannon WD, Vittori JM. The incidence of healing in arthroscopic meniscal repairs in ACL reconstructed vs. stable knees. Am J Sport Med 1992; 20:176.
37. Henning CE, Lynch MA, Clark JR. Vascularity for healing of meniscus repairs. Arthroscopy 1987; 3: 13.
38. Henning CE, Lynch MA, Yearout KM et al. Arthroscopic meniscal repair using an exogenous fibrin clot. Clin Orth 1990; 252: 64.
39. Rimmer MG, Nawana NS, Keene GCR et al. Failure strengths of different meniscal suturing techniques. Arthroscopy 1995; 11: 146.
40. Albrecht-Olsen P, Lind T, Kristensen G et al. Failure strength of a new meniscal arrow repair technique: biomechanical comparison with horizontal suture. Arthroscopy 1997; 13: 183.
41. Asik M, Sener N, Akpinar S et al. Strength of different meniscus suturing techniques. Knee Surg Sports Traumatol Arthroscopy 1997; 5: 80.
42. Dervin GF, Downing KJW, Keene GCR et al. Failure strengths of suture versus biodegradable arrow for meniscal repair: an in vitro study. Arthroscopy 1997; 13: 296.
43. Song EK, Lee KB. Biomechanical test comparing the load to failure of the biodegradable meniscal arrow versus meniscal suture. Arthroscopy 1999; 15: 726.
44. Barber FA, Herbert MA. Meniscal repair devices. Arthroscopy 2000; 16:613.
45. Perdue PS, Hummer CD, Colosimo AJ et al. Meniscal repair: outcomes and clinical follow-up. Arthroscopy 1996; 12: 694.
46. Horibe S, Shino K, Maeda A et al. Results of isolated meniscal repair evaluated by second-look arthroscopy. Arthroscopy 1996; 12: 150.
47. Asahina S, Muneta T, Yamamoto H. Arthroscopic meniscal repair in conjunction with ACL reconstruction. Arthroscopy 1996; 12: 541.
48. Horibe S, Shino K, Nakata K et al. Second-look arthroscopy after meniscal repair. J Bone Joint Surg [Br] 1995; 77B: 245.
49. Asahina S, Muneta T, Hoshino A et al. Intermediate results of meniscal repair in ACL reconstructed knees. Am J Sport Med 1998; 26: 688.
50. Van Trommel MF, Simonian PT, Potter HG et al. Different regional healing rates with the outside-in technique for meniscal repair. Am J Sport Med 1998; 26: 446.
51. Hurel C, Mertens F, Verdonk R. Biofix resorbable meniscus arrow for meniscal ruptures: results of a 1-year follow-up. Knee Surg, Sports Traumatol, Arthrosc 2000; 8: 46.
52. Escalas F, Quadras J, Caceres E et al. Tfix anchor sutures for arthroscopic meniscal repair. Knee Surg, Sports Traumatol, Arthrosc 1997; 5: 72.
53. Albrecht-Olsen P, Kristensen G, Burgaard P et al. The arrow versus horizontal suture in arthroscopic meniscus repair. Knee Surg, Sports Traumatol, Arthrosc 1999; 7: 268.
54. Austin KS, Sherman OH. Complications of arthroscopic meniscal repair. Am J Sport Med 1993; 21: 864.
55. Ross G, Grabrill J, McDevitt E. Chondral injury after meniscal repair with bioabsorbable arrows. Arthroscopy 2000; 16: 754.
56. Calder SJ, Myers PT. Broken arrow: a complication of meniscal repair. Arthroscopy 1999; 15: 651.
57. Anderson K, Marx RG, Hannafin J et al. Chondral injury following meniscal repair with a biodegradable implant. Arthroscopy 2000; 16: 749.
58. Whitman TL, Didruch DR. Transient posterior knee pain with the meniscal arrow. Arthroscopy 1998; 14: 762.
59. Kimura M, Hagiwara A, Hasegawa A. Cyst of the medial meniscus after arthroscopic meniscal repair. Am J Sport Med 1993; 21: 755.
60. Hutchinson MR, Ash SA. Failure of a biodegradable meniscal arrow. Am J Sport Med 1999; 27: 101.
61. Johnson MJ, Lucas GL, Dusek JK et al. Isolated arthroscopic meniscal repair: a long-term outcome study (more than 10 years). Am J Sport Med 1999; 27: 44.
62. Venkatachalam S, Godsiff SP, Harding ML. Review of the clinical results of arthroscopic meniscal repair. The Knee 2001; 8: 129.