Introduction

The meniscus serves a fundamental role in knee kinematics, important for load transmission, shock absorption and knee stability [1]. Trauma to the meniscus is common. In the United States (US) [2]the incidence of meniscus injury is 0.6–0.7 tears per 1000 person years; this varies across populations [2]. Whilst meniscus tears can occur across all ages, sexes and activity levels, the specific tear types and treatments vary [2]. The incidence of meniscal injuries typically follows a two-peak distribution, with a significant proportion of traumatic tears occurring in younger, more active groups (female: 11–20 years; male: 21–30 years), or relatively older groups, potentially due to degenerative joint disease (female: 61–70 years; male: 31–40 years) [3]. In males, the number of meniscal tears is generally higher than in females, and the degenerative pattern occurs earlier but falls precipitously after the age of 40; comparatively, females show two widely disparate peak incidences, with the degenerative pattern peaking later, but remaining stable thereafter, to resemble the incidence seen in males after the age of 70 [3]. The characteristics of the two-peak distribution vary between studies, particularly across different geographies [4,3].Moreover, meniscal tear is associated with Anterior Cruciate Ligament (ACL) injury and occurs with a greater incidence in patients who do not undergo arthroscopy within eight weeks of injury [5].

Conservative therapy (e.g. physiotherapy, rest, symptom monitoring) is usually the first line of treatment following a suspected meniscal tear [6]. Nonetheless, meniscal injuries commonly require surgery, particularly when ACL reconstruction is needed or when symptoms are more severe (e.g. locked knee) [7,8]. Approximately 850,000 meniscus surgeries are conducted annually in the US, comprising 10–20% of orthopaedic surgeries each year [2].Surgical options for meniscus tears can be broadly grouped into meniscectomy and meniscal repair [8]. Meniscectomy involves removing the damaged tissue and contouring the remaining healthy meniscal tissue to provide a stable peripheral rim, resulting in faster recovery and a reduced risk of re-tear [9]. Despite these short-term benefits, removal of the meniscal tissue results in bone-on-bone friction and may increase the long-term risk of Osteoarthritis (OA) and requirement for joint replacement [10,11].

Meniscal repair involves leaving some or all of the meniscal tissue in situ and using stitches to close the tear [8]. Whilst retention of the viable tissue is beneficial as it may reduce the risk or delay the onset of OA [2], meniscal repair requires a longer recovery period compared with meniscectomy, ranging from 4–12 months post-operation compared with 7–9 weeks, respectively [13, 14]. A large database study indicated that the rate of early complications are significantly higher following repair (1.2%) compared with meniscectomy (0.8%) [15]. However, the same study found that the rate of re-operation was significantly lower following repair (2.1%) than meniscectomy (5.3%) [15].The features of meniscectomy and meniscus repair create a dichotomy for healthcare providers and patients. Meniscectomy offers a faster recovery compared with repair, which is particularly beneficial to sports professionals, for example, looking to return to activity quickly [9, 8, 16]. However, meniscectomy is associated with a greater long-term risk of OA, functional limitation and mobility impairment [9,8]. Moreover, with health systems facing increasing financial pressures, costs may influence surgical decision-making. However, there is no consensus on the most cost-effective procedure. Whilst repair is associated with higher short-term costs, due to greater surgical complexity and recovery time, the reduced risk of OA contributes to its long-term cost-effectiveness [17, 2].The aim of this review is to assess guidelines on the surgical management of meniscus tears, and to consider the extent to which the guidelines are reflected in practice by reporting the trends in meniscus repair and meniscectomy procedure volumes.

Methods

Two targeted literature reviews were conducted between May–August 2021; the first sought to capture the clinical guidelines covering meniscal repair, and the second to identify procedure volume data. For both, results were limited to data available in the English language.A snowballing approach was adopted to identify international guidelines for meniscal repair covering the US/Canada, Europe and Japan. This approach began with known guidelines including those from the European Society for Sports Traumatology, Knee Surgery And Arthroscopy (ESSKA) and the American Academy of Orthopaedic Surgeons (AAOS), then identified additional guidelines based on searches of the reference lists and relevant surgical societies in each region. Further searches of medical literature (PubMed) and internet searches were also conducted, using the search terms ‘meniscal repair’, ‘meniscectomy’, ‘meniscal resection’ and ‘meniscal surgery’. Guidelines published from the year 2000 onwards were included. A data extraction template was developed to extract consistent information from each guideline, including patient selection, criteria for meniscal repair, details of surgical approaches and concomitant treatments, where stated. Data on meniscal repair procedure volumes were identified through targeted medical literature and internet searches. Search terms relating to meniscal surgery, meniscal resection and meniscal repair were used, including Medical Subject Headings (MeSH) terms relating to surgical procedure trends and time series. Studies reporting longitudinal procedure volumes, including meniscal repair and meniscectomy (with or without ACL repair) were considered for inclusion to ensure that trends in surgery could be identified, rather than point estimates at a given time. Studies published prior to 2010 were excluded on the basis that these were unlikely to reflect current practice and recent recommendations from the guidelines; studies published after 2010 with time series starting prior to 2010 were considered for inclusion to maximise the time series data included. Studies were identified for inclusion for based on the countries identified in the guideline review in an attempt to match the procedure volume data by country; studies reporting procedure volume data for countries which did not have identified meniscal repair guidelines were excluded. Data on procedure volumes and case-mix (i.e. the proportion of meniscal repair versus meniscectomy) were extracted using a data extraction template.

Results

Clinical guidelines on meniscal repair

Seven guidelines published between 2008–2020 were included in the analysis, spanning Canada [18], France [19], Japan [20], the Netherlands [21], United Kingdom (UK) [22], US [23] and Europe as a whole [7] (Table 1,2). Guidelines on meniscal tears included recommendations for both conservative management and surgical interventions; four guidelines were specific to meniscal tears [3,18,21,22], whilst three (in Europe [7], France [19], Japan [20]) included guidance on the management of ACL injuries, with or without meniscal injury. Guidelines generally emphasised the need to preserve the meniscus and highlighted the long-term benefits of repair compared with meniscectomy, such as greater patient satisfaction and activity post-repair (Europe [19]), and reduced risk of progressive OA (Europe [7], France [19], Japan [20], US [3]). Three guidelines recommended meniscal repair as the first line of surgery where feasible (Europe [7], France [19], the Netherlands [21]); for non-repairable tears, partial meniscectomy was recommended on the condition that the injury is symptomatic (France [19], UK [22]).Guidelines predominantly focused on patient age and tear type as two key indications determining preferences for meniscal repair versus meniscectomy. Meniscal repair was specifically recommended for its benefit in younger (<40 years) but not older (>40 years) patients in the US [23], or those with degenerative tears or OA; in these patients, meniscectomy was recommended (Europe [7], France [19], the Netherlands [21], US [23]). An important consideration guiding the preference for repair in younger patients was the expected risk of arthritic progression following meniscectomy (US [23]). Undergoing meniscectomy earlier in life may increase the duration patients suffer arthritic symptoms following the procedure, whereas older patients are less likely to be impacted by this effect due to shorter life-expectancy and greater likelihood of pre-existing OA symptoms (US [23]). Repair was recommended over meniscectomy for acute or recent tears (Europe [7], France [19], UK[22], US [20]), traumatic tears (Europe [7], France [19]), well-vascularised tears (France [19], US [23]), peripheral tears (France [19], the Netherlands [21]), lateral meniscus tears (Canada [18], France [19], the Netherlands [21]), and vertical tears (US [23]). However, guidelines noted little benefit of repair in avascular tears (US [23]), non-traumatic tears (France [7]), radial tears (Europe [7], US [23]) and horizontal tears (US [23]); for these tears, meniscectomy was recommended. The level of detail describing the differential indications for repair versus meniscectomy varied across the guidelines. For instance, the Japanese guidelines were restricted to meniscal repair with concomitant ACL injury (Japan [20]), and the Canadian guidelines focused on knee arthroscopy procedures for the meniscus, with limited detail on repair technique (Canada [18]). (Table 1) (Table 2).

Table 1: Clinical guidelines on meniscal repair: indications covered.

Abbreviations. AAC: Arthroscopy Association of Canada; AAOS: American Academy of Orthopaedic Surgeons; ACL: anterior cruciate ligament; BASK: British Association for Surgery of the Knee; ESSKA: European Society for Sports Traumatology, Knee Surgery and Arthroscopy; HAS: Haute Autorité de Santé; JOA: Japanese Orthopaedic Association; NOV: Nederlandse Orthopaedische Vereniging; UK: United Kingdom; US: United States.

Table 2: Clinical guidelines on meniscal repair: eligibility criteria and considerations.

Abbreviations: AAC: Arthroscopy Association of Canada; AAOS: American Academy of Orthopaedic Surgeons; ACL: anterior cruciate ligament; BASK: British Association for Surgery of the Knee; BMI: body mass index; ESSKA: European Society for Sports Traumatology, Knee Surgery and Arthroscopy; HAS: Haute Autorité de Santé; JOA: Japanese Orthopaedic Association; MRI: magnetic resonance imaging; NOV: Nederlandse Orthopaedische Vereniging; OA: osteoarthritis; UK: United Kingdom; US: United States.

Meniscal surgery procedure volume trends

Nine published sources covering France [1], Japan (n=2) [24,25], the Netherlands [26], UK [27] and US (n=4) [17, 28-30] were identified (Table 3–5); no real-world data from Canada or Europe as a whole were identified. Only five studies specifically reported procedure volume trends, from France [1], Japan (n=2) [24,25], the Netherlands [26] and US [28] (Table 3-4). Data sources included governmental bodies, national insurance databases and observational datasets; studies focused on indications including meniscal repair, meniscectomy, ACL reconstruction and ACL reconstruction with repair. The registry-based data analysed in the Netherlands study did not discern between meniscectomy and repair. An overview of meniscal repair trends is shown in Table 3, and a summary of data extracted from each study in Table 4. Overall, the total number of repair procedures increased clearly across all geographies between 2004–2017 (Table 3); in three studies this resulted in a significant increase in the proportion of meniscus repairs at the expense of meniscectomies (France [1], Japan [n=2] [24,25]). In Japan, the proportion of meniscus repairs significantly increased between 2007 and 2015, from 7.0% to 25.9%; the proportion of meniscectomies decreased accordingly over the same period (92.8% to 73.3%) [25].All five studies reported procedure trends by age, indicating that the proportion of injuries repaired increased across most age groups over the studied period. A similar rate of increase in meniscal repairs was reported across patients in all age groups between 20–70 years in France [1] and Japan [24]. Although the increase in the rate of repair was similar across all age brackets, the reduction in meniscectomy appeared greatest in patients <40 years, whilst remaining stable in those >60 years (France) [1]. Notably, the proportion of injuries repaired decreased in the US for three age groups (35–44, 45–54 and 55–64 years) [28].Despite the increase in meniscal repair procedures, the overall proportion of repairs versus meniscectomy still represented the minority of meniscal surgery procedures across all studies. Analyses of subgroups identified only one group ― Japanese patients <30 years in 2014 (the final year included in the study) ― where meniscal repair was the dominant procedure (50.3% of all meniscal surgical procedures) [25].  T h r e e studies reported procedure trends by tear type (France [1], Japan [25], US [28]). One study conducted a subgroup analysis using patients <40 years and those >50 years, based on the assumption that traumatic and degenerative lesions are more prevalent in these subgroups, respectively; data indicated that the shift from meniscectomy to repair was particularly strong in patients <40 years, suffering from traumatic tears (France) [1]. Comparatively, the number of meniscectomies remained stable in patients >50 years, with predominantly degenerative tears (France) [1]. The proportion of patients undergoing repair increased significantly for those with lateral and medial tears, but with a greater increase in the former (Japan) [25]. Moreover, a greater increase in the number of repairs between 2005– 2011 was observed when an ACL reconstruction was also performed (48.3%) compared to without (11.4%) (US) [28].

Table 3: Overview of volume trends in meniscal repair procedures. ^a The volume of meniscal repairs is listed as reported in each individual study. ^b The proportion of total meniscal surgeries including: (i) meniscectomy and (ii) meniscus repair. ^c The proportion of total meniscal surgeries including: (i) meniscectomy, (ii) meniscus repair, and (iii) both meniscectomy and repair.

Abbreviations. US: United States.

Table 4: Summary of studies on procedure trends.

Abbreviations. ACL: anterior cruciate ligament; US: United States.