Anterior meniscopexy: a meniscal sparing technique for the treatment of locking but intact discoid lateral meniscus
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Symptomatic discoid lateral meniscus without tears has traditionally been treated with excision of part or the entire meniscus. Resection of 15–34% of the meniscus increases tibiofemoral contact pressures by more than 350%. Treatment of discoid lateral meniscus with partial or total meniscectomy in childhood increases the risk of early-onset osteoarthritis in the knee. The incidence of osteoarthritis is directly proportional to the amount of meniscal tissue resected. This paper describes the meniscus-preserving technique of meniscopexy and presents the outcomes of all patients who have undergone this procedure in the management of lateral discoid meniscus in a single unit over a 14-year period.
A retrospective study was carried out reviewing all patients who underwent meniscopexy for the treatment of MRI-confirmed discoid lateral meniscus without meniscal tear between 2001 and 2015 with a minimum of 1-year follow-up. Eleven patients (12 knees) were identified using a patient database of all patients that had undergone this procedure in our institution. Two patients were excluded from the final results, so nine patients (10 knees) were scored post-operatively at last follow-up using the Lysholm knee score. We reviewed all available post-operative MRI scans and recorded any complications.
Four patients were male and seven were female. The median age of the patients at the time of surgery was 9 (6–14), and the median follow-up was 4.5 years (2–14). The median Lysholm knee score was 91 (86–100). The outcome for all patients scored was either good or excellent.
The established treatment options for symptomatic discoid lateral meniscus without associated tear involve resection of meniscal tissue. Using this technique, all the meniscal tissue is preserved, thus reducing the risk of arthritic change in the future. MRI studies performed post-operatively suggested normalisation of meniscal morphology with time. Meniscopexy offers an effective alternative to the established treatment options in the management of symptomatic discoid lateral meniscus without meniscal tears.
Level of evidence
KeywordsMeniscus Discoid MRI Meniscopexy
Lateral discoid meniscus is a cause of snapping, locking and pain in the knees of children and adolescents. The incidence of lateral discoid meniscus is estimated to be between 3 and 5% in the general population [6, 11], but the true incidence of discoid meniscus is unknown as many people may remain asymptomatic. The most commonly used classification system is that of Watanabe which is based on arthroscopic appearance . Watanabe classified discoid menisci with normal tibial attachments as either complete or incomplete, depending on how much of the tibial plateau was covered. Wrisberg variants include both discoid and near-normal-shaped menisci that are hypermobile .
Traditional treatment for a symptomatic discoid meniscus is excision (partial or total) . The meniscus contributes to load transmission across the tibiofemoral joint. It protects the articular cartilage resulting in the damage of loads after meniscectomy. Biomechanical studies have shown that at least 50% of the compressive load of the knee is transmitted through the meniscus in extension and approximately 85% at 90° of flexion . After combined medial and lateral meniscectomy, the contact area is reduced by up to 75% and the contact stress on the articular cartilage increased by 235% . This significantly increases the load per unit area and results in articular damage and degeneration.
Partial meniscectomy has also been shown to significantly increase contact pressures . Seedholm and Hargreaves  found that resection of 15–34% of the meniscus increased tibiofemoral contact pressures by more than 350%. Following partial meniscectomy the incidence of osteoarthritis seems to be dependent on the amount of meniscal tissue resected .
A number of studies have shown deleterious consequences of total and partial meniscectomy  with the development of progressive osteoarthritis. The prognosis has been shown to be particularly poor following meniscectomy of the discoid meniscus [10, 16, 21]. The deleterious consequences of total and partial meniscectomy are more pronounced in children and adolescents in whom the long-term effects of meniscectomy are magnified by activity level and longevity .
Anterior meniscopexy, a technique that preserves meniscal tissue and removes the painful locking/clicking caused by a discoid meniscus, has been described previously . This differs from partial or complete resection of the meniscus, as all the meniscal tissue is preserved to protect the articular surfaces and therefore potentially avoids the potentially deleterious long-term effects of meniscectomy. This study represents a case series of patients treated using this technique at The Robert Jones and Agnes Hunt Orthopaedic Hospital.
Materials and methods
This is a retrospective study looking at outcome following meniscopexy performed on 11 patients (12 knees) between 2001 and 2015. Patients were identified using a database of all patients undergoing this procedure under the care of the senior author.
All patients had pre-operative symptoms of lateral sided knee pain as well as painful catching and clicking within the knee. All patients had undergone pre-operative MRI suggesting a discoid meniscus without meniscal tear. All patients included in the study had at least 12 months of follow-up post-operatively. All patients, other than those lost to follow-up and those that went on to have further surgery, were scored post-operatively at last follow-up using the Lysholm knee score .
Five patients (six knees) went on to have post-operative MRI scans to access the morphology of the meniscus following meniscopexy, although MRI was not requested as standard following surgery. Only those patients in whom a further MRI scan was clinically warranted went on to have a post-operative MRI. One patient had two post-operative MRI scans.
With regards to the operative technique, firstly an arthroscopic assessment of the knee is undertaken. This is performed to confirm the presence of a discoid meniscus, assess both the integrity and the stability of the discoid lateral meniscus, to exclude a meniscal tear and to identify a Wrisberg-type meniscus.
Four patients were male and seven were female. The median age of the patients at the time of surgery was 9 [6, 7, 8, 9, 10, 11, 12, 13, 14]. All the patients apart from one were treated for stable discoid meniscus without meniscal tears. One patient was treated for an unstable Wrisberg variant.
One patient was lost to follow-up prior to being scored. However, at last follow-up 3 months following the surgery the patient was asymptomatic and had a normal clinical examination of the knee. One patient went on to have further surgery, so no Lysholm score was recorded. They had initial resolution of their symptoms, but then went on to develop recurrence. An MRI was performed which showed some thickening of the meniscus and a possible tear. An arthroscopy was performed at 6 months following the initial surgery, and this showed that one of the sutures had cut through the meniscus. The meniscus was trimmed back to a stable rim. At last follow-up, they were doing well symptomatically 9 years following the surgery and they remain under review.
A Lysholm score was recorded at last follow-up for nine patients (10 knees). The median Lysholm knee score was 91 (86–100). The outcome for all patients was either good or excellent at last follow-up. The median follow-up was 4.5 years (2–14 years).
With regards to complications, one patient developed a significant limb length discrepancy (1.5 cm) as a result of overgrowth. The limb lengths were not recorded pre-operatively, so it is unclear whether this was as a direct result of the surgery, but became apparent following the surgery so was attributed to the procedure. This is currently being monitored and will be treated with proximal tibial epiphysiodesis when the patient reaches an appropriate age. A second patient developed a mild varus alignment to the tibia, again due to overgrowth. It is intended that guided growth will be used to manage this in due course if required.
Five of the patients had post-operative MRI scans. The latest scans were an average of 4.5 years following the surgery. Of the five patients who had post-operative MRI scans, four of the latest post-operative scans showed improvement in the morphology of the meniscus. One patient had sustained a tear of the posterior horn of the lateral meniscus on MRI scan. They went on to have further surgery as previously described.
Of note, one patient went on to have two post-operative MRI scans. The first scan was done at 6 months following surgery (the patient had fallen and injured the knee), and the second scan at 3 years post-operatively. The scan at 6 months showed some improvement in the morphology of the lateral meniscus when compared with the pre-operative scans, but the meniscus remained discoid in morphology. The scan done at 3 years following the surgery, however, showed significant change in the morphology of the meniscus and apparent resolution of the abnormal discoid shape.
The most important finding of the present study was that treatment of stable discoid meniscus with meniscopexy leads to good or excellent results when patients are assessed post-operatively using the Lysholm knee score. The findings of this study would suggest that meniscopexy offers an alternative to the established surgical management of partial meniscectomy in the management of discoid meniscus without tears. The advantage of meniscopexy is that there is preservation of all the meniscal tissue and therefore a reduction in the risk of arthritic change in the future. The surgical technique with regards to meniscopexy in the treatment of discoid meniscus of the knee has previously been described, but the results have never previously been published . The procedure has not been described elsewhere in the management of discoid meniscus in children.
Traditionally, the treatment of choice for symptomatic stable or unstable discoid lateral menisci was open total meniscectomy, as tissue left after partial meniscectomy was considered abnormal [15, 24]. Today, however, preservation of a stable rim is desirable as the incidence of osteoarthritis following partial meniscectomy is dependent on the amount of meniscal tissue resected . The results following partial resection of non-Wrisberg-type discoid meniscus are good on short-term follow-up [7, 20]. Various techniques have been described to carry out the partial meniscectomy [9, 14, 20]. Ahn et al.  looked at long-term results of 38 children (48 knees) who underwent arthroscopic reshaping for symptomatic discoid lateral meniscus. Treatment consisted of established techniques including partial meniscectomy and subtotal meniscectomy. The clinical results were comparable to the results of this study, with an average Lysholm score of 97.8. However, at an average follow-up of 10 years, degenerative changes were observed in 23% of cases following partial meniscectomy and 88% of cases following subtotal meniscectomy.
Wroble et al. reported long-term follow-up following meniscectomy in patients younger than 16. 90% had abnormal radiographs and 63% of patients results rated as unsatisfactory with an average follow-up of 21 years. More unsatisfactory results occurred in patients with a follow-up period of longer than 26 years, in those with substantial instability, and in males . The goal in treatment planning should be to preserve as much native meniscus as possible . Meniscopexy allows preservation of all the meniscal tissue and therefore theoretically protects the knee from the risk of osteoarthritic change in the future. Meniscopexy has been used to successfully treat patients with disc displacement and degenerative joint disease of the temporomandibular joint .
Five of the patients (six knees) went on to have an MRI scan post-operatively. Scans showed normalisation of the meniscal morphology in four of the five patients. These were performed at an average of 4.5 years following meniscopexy. The findings of the post-operative MRI scans give objective evidence that meniscopexy successfully alters the morphology of the meniscus and is in keeping with the subjective improvement in the patient’s symptoms and the encouraging Lysholm scores recorded post-operatively.
Interestingly, one patient went on to have MRI scans post-operatively at 6 months and 3 years following the procedure. The initial MRI scan suggested that there had been little improvement of the discoid nature of the meniscus. However, the scan done at 3 years showed a marked improvement compared to the initial scan. This suggests that there may be a remodelling process of the meniscus with time following meniscopexy and that improvements may not be visible on MRI until at least 6 months following the procedure. It may be that by securing the meniscus and creating a more anatomically normal meniscus the forces going through the meniscus are normalised and this leads to an increasingly normal morphology with time secondary to meniscal remodelling.
The single MRI that did not show improvement in the meniscal morphology relates to the only patient that suffered recurrence of mechanical symptoms in the knee following meniscopexy and required further surgery. In this case, one of the sutures had pulled through the meniscus and partial meniscectomy was carried out to trim the meniscus back to a stable rim. This is the accepted surgical management for symptomatic discoid meniscus and therefore offers an established treatment as a backup procedure should such a complication occur.
The only other complications related to stimulation of growth following surgery adjacent to the growth plate. The insertion of the bone anchors into the proximal tibial epiphysis may have stimulated growth. This will be monitored and treated with an epiphysiodesis when appropriate. It is helpful to obtain documented measures of lower limb length and alignment prior to surgery to enable accurate monitoring and management of possible growth disturbance following this procedure.
Meniscopexy is indicated when a symptomatic discoid meniscus shows only slight degeneration or a minimal tear and when the meniscus is a Wrisberg variant. The patients in this series were treated for stable discoid meniscus without significant meniscal tears. The use of meniscopexy in the treatment of menisci with significant tears would be ineffectual as the tear would prevent anterior traction of the anterior horn from acting upon the posterior component of the meniscus.
Only one of the patients in the current series was treated for a Wrisberg variant. At arthroscopy, a mobile subluxing meniscus was identified. Treatment of the Wrisberg variant is more controversial in the literature. Some authors argue that partial meniscectomy is inappropriate as it leaves an unstable rim of meniscus to cause symptoms in the future . More recent reports of saucerisation of a discoid meniscus and reattachment present an alternative option [12, 17].
Meniscopexy was carried out in the same way on this patient. The meniscus was secured with two Mitek anchors, and following fixation the meniscus no longer subluxed. The patient’s symptoms resolved post-operatively, and at last follow-up they had a Lysholm score of 100 suggesting meniscopexy can successfully be used in the management of Wrisberg variant discoid meniscus.
The limitations of this study relate to the numbers of patients, the retrospective nature of the study and the period of follow-up. Although the results are based on a small series of patients, they are encouraging. All the patients had Lysholm scores of over 86 at last follow-up suggesting good or excellent results and had resolution of symptoms including pain, clicking and locking of the knee. Only one patient had recurrence of the clicking and locking in the knee and went on to have further surgery.
A randomised controlled trial comparing meniscopexy against partial meniscectomy would be the gold standard. Ideally, a larger series of patients is required and the follow-up is relatively short considering the average age of the patients was 10.2 years at the time of operation. While the results are encouraging and suggest that meniscopexy can be used to successfully treat symptomatic discoid meniscus, we need to follow all the patients through to adulthood to ensure function is maintained and to confirm that meniscopexy is advantageous over partial meniscectomy in that it protects the patients from the risk of early degenerate change in the knee.
The outcome of this study is clinically relevant, as good to excellent results were achieved using the meniscopexy technique in the treatment of those select group of patients suffering mechanical symptoms on the background of discoid meniscus in the absence of a meniscal tear. Meniscopexy offers a treatment option that resolves the patient’s symptoms without exposing them to partial or complete meniscectomy which can lead to early degenerative changes in the knee.
Meniscopexy can be used in the treatment of symptomatic discoid meniscus without tear leading to good or excellent outcome. Meniscopexy is advantageous over established techniques as it allows preservation of all the meniscal tissue and therefore theoretically protects the knee from the risk of osteoarthritic change in the future.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
There is no funding source.
No ethical approval was required. This is a retrospective study of outcome.
No informed consent was obtained although consent was obtained at clinic in order to get the patients outcome scores.
- 11.Jordan MA, Duncan JB, Bertrand SL (1993) Discoid lateral meniscus: a review. South Orthop J 2(4):239–253Google Scholar
- 20.Tegner Y, Lysholm J (1985) Rating systems in the evaluation of knee ligament injuries. Clin Orthop Relat Res 198:43–49Google Scholar
- 22.Watanabe M, Takeda S, Ikeuchi H (1979) Atlas of arthroscopy, 3rd edn. Igaku-Shoin, TokyoGoogle Scholar
- 23.Wroble RR, Henderson RC, Campion ER et al (1992) Meniscectomy in children and adolescents. A long-term follow-up study. Clin Orthop Relat Res 279:180–189Google Scholar