Comparison between conservative and prophylactically concurrent meniscoplasty on the asymptomatic knee in children with bilateral DLM: a retrospective study

doi:10.21203/rs.3.rs-2307158/v1

Purpose

This study aimed to compare clinical outcomes between concurrent meniscoplasty and conservative management on the asymptomatic side in children with bilateral discoid lateral meniscus (DLM) operated on the unilaterally symptomatic side.

Methods

Patients under 14 with unilaterally symptomatic bilateral DLM underwent arthroscopic meniscoplasty were eligible. Patients were divided into two groups: children underwent meniscoplasty on the symptomatic side, with the asymptomatic side conservatively treated (group1); Children underwent meniscoplasty on both the symptomatic and asymptomatic sides concurrently (group2). Functional outcomes were evaluated using the Lysholm score and Ikeuchi score. Survival analysis of the occurrence of symptoms was applied by Kaplan‒Meier model.

Results

A total of 50 patients were eligible. For the average Lysholm scores, groups 1 and 2 of the previously asymptomatic side were 90.86±8.25 and 92.62±8.68. The mean survival time was 9 years in group 1 and 5 years in group 2. The Kaplan‒Meier survival analysis of the occurrence of symptoms showed no statistically difference between two groups (p=0.162), and the terminal survival rates in the two groups were 86.2% and 81.0%, respectively.

Conclusion

Concurrent meniscoplasty on the asymptomatic DLM provided the same functions with the conservative treatment. Conservative group showed lower occurrence of symptoms and longer survival time.

Trial registration

The trial had been registered on the Chinese Clinical Trial Registry, with the number ChiCTR2000034577 on 10^th July, 2022.

Discoid meniscus

discoid lateral meniscus

children

arthroscopic meniscoplasty

Discoid lateral meniscus (DLM) is one of the abnormalities in the cartilage of the knee joint and covers larger areas of the tibial plateau than the normal meniscus^[1]. Common mechanical symptoms of DLM injuries include pain, snapping knee, limited range of motion (ROM), and swelling^[1-3]. Research reported that its prevalence in Asians (16%-20%) was much higher than in Western countries (0.4%-5.2%)^[4-7]. DLM was first reported by Young et al. in 1889 from a cadaver study with a thicker body and disk-like shape^[8]. Based on its disk-like shape, Watanabe and his team classified discoid meniscus into three types: complete discoid meniscus, incomplete discoid meniscus, and Wrisberg-type meniscus^[9]. The morphology of the DLM reduced the stability of the knee and weakened the meniscal-capsular attachment, which increased the risk of injury compared with the normal meniscus^[10].

To address DLM, many surgical techniques have been reported, such as subtotal or total meniscectomy, but research has reported that total meniscectomy may result in early arthritis changes^[11]. Meniscoplasty is considered the gold standard, as it removes extra parts and restores the shape of the normal meniscus^{[4, 7, 12]}.

DLM without symptoms is hard to discover, and DLM in children was often found in incidence, such as running, falling, and knee snapping, and adolescents were often found in pain or popping^[13]. Patel et al. conducted research that operated unilaterally and reported an increased rate of occurrence of symptoms on the contralateral knee^[14]. Kocher et al. suggested observation instead of any intervention when dealing with asymptomatic DLM, while no research has been conducted yet^[10]. In clinical practice, it is difficult to make satisfactory decisions regarding the solution of asymptomatic DLM due to the lack of guidelines and proposals of established methods for this question.

Therefore, the purpose of this study was to answer the question of which was the optimal choice for the treatment of asymptomatic DLM. To achieve this question, the study compared the clinical outcomes between prophylactically concurrent meniscoplasty and conservative management on the asymptomatic side in children with bilateral discoid lateral menisci operated the symptomatic side. We hypothesized that conservative management provides better results for asymptomatic DLM.

Study design

This retrospective study was approved by the Biomedical Ethics Committee in the institute on March 9, 2020, with approval number 286. Additionally, the trial was registered on the clinical registry. This study was funded by the hospital. The case-report form (CRF) recorded patients aged less than 14 years of age with a diagnosis of DLM who underwent arthroscopic meniscoplasty from 2010 to 2021. All surgeries were performed by surgeons from the same institute who had rich clinical experience in arthroscopy. All participants provided written informed consent before surgery.

Patient selection

The hospital information system (HIS) of the institutional database of medical and operative records was retrieved, and the inclusion criteria were as follows: 1. Patients ≤14 years of age; 2. Patients were treated by arthroscopic meniscoplasty between January 1^st 2010 and April 9^th 2021; 3. Patients were diagnosed with bilateral DLM by MRI and arthroscopy and were found symptomatically on one side; 4. Patients who had at least 1 year of postoperative follow-up; 5. Patients who signed informed consent before participation.

The exclusion criteria were as follows: 1. Patients diagnosed with discoid medial meniscus (DMM); 2. Patients with other knee diseases, such as ligament injury, knee dislocation; 3. Patients unwilling or unable to complete the follow-up questionnaires; 4. The uninjured side had a history of knee surgery; 6. Patients with meniscus sutures; 7. Patients were diagnosed with bilateral DLM with symptoms on both sides.

Patients were categorized according to their injury type and surgical options. Based on their surgical options, the patients were divided into 2 groups: group 1 included patients diagnosed with bilateral DLM undergoing unilateral meniscoplasty on the symptomatic side and conservative management on the asymptomatic side. Group 2 included patients with bilateral DLM and to prevent predictable meniscus injury who had a strong willingness to undergo bilateral meniscopalsty concurrently on both the symptomatic and asymptomatic sides.

Surgical procedure

All arthroscopic surgeries were performed in one center, and all surgeons were experienced. Patients were under general anesthesia in the supine position. Arthroscopy was performed through the medial and lateral portal of the parapatellar region, and a knee diagnosis was performed anteromedially and anterolaterally to observe the intra-articular structures. Then, the lesion was found and measured, including the type of DLM, the type of lesion and the quality of meniscus tissue. The next step was to reshape the meniscus by performing meniscoplasty, trimming the meniscus to 6 to 8 mm in the periphery. After smoothening the edge, knee stability was tested, and only a stable meniscus was included in the study. The unstable meniscus was stabilized by the outside-in suture technique.

The postoperative rehabilitation was as follows. For the first 4 weeks, patients’ range of motion was restricted to no more than 90 degrees, and they performed partial weight-bearing (started at 2 weeks after surgery at 20% of full weight-bearing) no more than 50% of full weight-bearing. After 4 to 6 weeks, patients were asked to reach full range of motion and progressively perform full weight-bearing. After 6 months, patients were able to return to sports.

Conservative treatment for asymptomatic DLM

Patients with bilateral DLM operated on symptomatic side and chose conservative treatment on the asymptomatic side were suggested for protective training programs. Detailed trainings included quadriceps, hamstrings, lateral and internal muscle groups, triceps strengthening and core stability exercise. Each training required at least 3 days per week, 3 sessions per day, 10 sets per session, using a theraband for resistance training. Precautions and attentions were listed, such as avoidance of sudden position changes, and avoidance of reversing during weight-bearing.

Patients’ medical reports

Data collected included sex, age, body mass index (BMI), periods from symptom to surgery, Watanabe classification of injury types, length of follow-up, condition in most recent follow-up, activities and sports.

Patients were asked to complete two self-evaluated scales. Functional status was evaluated by the Ikeuchi scale and Lysholm scale. The Ikeuchi scale contained 4 stages: excellent, good, fair and poor, and for each stage, a detailed explanation was provided for better understanding^[15]. The Lysholm scale contains 8 items: limp, support, locking, instability, pain, swelling, stair climbing, and squatting. The maximum score on the Lysholm scale was 100, and scores < 85 were considered fair or poor^[16]. Additionally, the Lysholm scale was completed on both sides of the knee to compare functional status.

Descriptive symptoms before and after surgery were recorded. The criteria for pain severity were based on the visual analog scale (VAS). The “locking” symptom was described as a sudden stuck in the knee with no clear reason, and patients were unable to move freely. The criteria for limited range for motion were described as patients unable to reach full range of motion, including full knee flexion or extension. The criteria for knee swelling were measured by tape and were asked to perform comparisons to the other side. The “snapping” symptom was described as a sound in the knee being heard when patients moved.

Statistical analysis

Data management and statistical analysis were performed with Statistical Product Service Solutions (SPSS) 22.0. The quantitative variables were described as the means and standard deviations (SDs), and the descriptive variables were described as frequencies or percentages. The X² test was applied for comparisons between the two groups. Continuous variables were analyzed by the independent t test. The survival analysis was applied by Kaplan‒Meier curves. The survival timepoint was defined as the occurrence time of symptoms (such as locking and pain with VAS score > 3) on the asymptomatic side of the knee^[17]. A p value < 0.05 was set as a significant difference.

Baseline characteristics

A total of 144 patients under the age of 14 were retrieved from January 1st 2010, to April 9th 2020. 50 patients were eligible for the research and agreed to participate. There were 39 female and 11 male participants, with a mean age of 9.54±3.53 (ranging from 5 to 14), and the average length of follow-up was 4.22±2.57 years, ranging from 1 year to 12 years. According to the Watanabe classification^[9], 64% of patients had a complete discoid meniscus, 34% had an incomplete discoid meniscus, and 2% had a Wrisberg-type meniscus. The baseline demographic data are shown in Table 1. No significant difference was found in age, BMI, length of follow-up, or Lysholm score before surgery.

Patient self-evaluated outcomes and clinical results

All patients reported better clinical results than preoperatively and were able to accomplish daily activities. Of the 50 patients, the presenting symptoms on the symptomatic knee were occasional pain in 26 (52%), locking in 3 (6%), limited ROM in 13 (26%), and snapping in 14 (28%). Among the 26 patients with pain, 19 (38%) reported pain after sports activities or long-term walking, 3 (6%) reported night pain, 4 (8%) reported pain and limp in wet weather, and 2 (4%) reported pain or uncomfortableness in up and down stairs. Additionally, only 14 patients (28%) returned to activity and sports without symptoms.

All participants completed the Ikeuchi and Lysholm scale questionnaires. Patients in fair or bad condition frequently suffer from mechanical symptoms and after-sport pain. The average Lysholm scores in the two groups on the symptomatic side were 71.58±6.85 and 72.83±9.35 preoperatively and 91.38±8.90 and 95.71±7.45 postoperatively. The average Lysholm scores of the previously asymptomatic side were 90.86±8.25 and 92.61±8.68, respectively. Detailed outcomes are presented in Table 2.

Survival analysis

The Kaplan‒Meier survival model was performed between the groups. No statistically significant difference was found in comparisons of the occurrence of symptoms (such as pain, locking, limited ROM, swelling or snapping) between the asymptomatic knee in both groups (p=0.162). The mean survival time defined as the time of occurrence of symptoms was 9 years in group 1 and 5 years in group 2. The terminal survival rates were 86.2% and 81.0%, respectively. The survival curve is presented in Figure 1.

Inserted Figure 1.]

The primary finding of this study is that for patients with unilaterally asymptomatic DLM, there is no significant difference in clinical results and functional status between arthroscopy and conservative management on the symptomatic side. However, a trend of a low rate of occurrence of symptoms and longer survival time was discovered in the conservative group.

Few studies have compared the outcomes of prophylactically concurrent meniscplasty or conservative treatment of asymptomatic DLM. Patel and his colleagues compared patients with both knee DLMs who underwent arthroscopy and found that patients who needed surgical treatment on the asymptomatic side were younger than patients who reported unilateral symptoms and had conservative treatment on the other side, especially for patients under 12 years old with complete DLM and Wrisberg-type DLM^[14]. However, Patel et al. did not discuss whether patients with both DLM with or without symptoms should undergo arthroscopy at an early age. Only descriptive data were provided.

Additionally, whether the asymptomatic side of patients with bilateral DLM should receive routine screening and undergo arthroscopy is still being debated. Some studies assessed the asymptomatic knee of the nonoperated side and suggested regular evaluation by MRI and X-rays in follow-ups^[18-20], and some research mentioned no treatment for children with asymptomatic DLM^[21-24]. However, few discussed the reason. Liu and his colleagues assessed the contralateral side in follow-ups after arthroscopy on the symptomatic DLM in patients with bilateral DLM by MRI and X-ray. They found a high rate (72.7%) of bilateral symptoms in Chinese populations. They suggested that prophylactic meniscectomy may be beneficial for a portion of patients with high-grade MRI abnormality, who may be unable to adapt the anatomic structures and to complete normal functions^[18]. Also, Bae and his colleagues believed that an asymptomatic DLM tear can result in degenerative changes in middle-aged patients^[25]. Lin et al.’s^[26] and Li et al.’s^[27] reported significant differences in biomechanics between DLM tears and normal meniscus tears, while no research reported biomechanical results compared with asymptomatic DLM. Although no consensus has been made, most studies have suggested nonoperation treatment for asymptomatic DLM^[21-24]. However, no research has reported functional outcomes or other subjective data on the assessment of asymptomatic contralateral knees. There was no suggestion of whether prophylactic surgery was needed on the asymptomatic side.

This study compared clinical results and self-reported functional outcomes in children undergoing conservative or surgical management in asymptomatic DLM and found that there was no statistically significant difference between the two managements. However, there seemed to be a trend that conservative treatment achieved a lower occurrence and longer period of appearance of new-onset symptoms on the asymptomatic side. This result may be evidence supporting future clinical treatment of children with asymptomatic DLM, and nonoperative treatment may be more favored than prophylactic surgery.

The present study had some limitations. This was a retrospective study, and the sample size of the study was small. Also, the groupings were made according to patients’ wishes, a risk of selection bias existed. Additionally, many patients have undergone surgery at an early age, and therefore, some contact can only be made with their parents, which may cause recall bias. Last, some patients who reported no symptoms refused to undergo extra imaging examinations.

The conclusion of this study showed that prophylactically concurrent meniscectomy reported no difference in functional scores on the asymptomatic side compared with the conservative treatment, while conservative group showed lower occurrence of symptoms and longer survival time.

Author contributions

Mingke You and Pengcheng Li made substantial contribution to the design of work, Mingke You and Kai Zhou performed statistical analysis and interpretation of data, and Gang Chen and Jian Li made corrections. All authors agreed to publish the article.

Acknowledgements

Not applicable.

Conflict of interest

The authors declare that there’s no conflict of interest.

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Table 1. Characteristics of baseline information and descriptive data of the 2 groups. N: number; BMI: body mass index; y: year

	Group1	Group2	p value
N.	29	21
Sex (Male/Female)	8/21	5/16
Age	8.55±3.37	10.90±3.36	0.020
BMI	18.46±4.69	18.38±5.89	0.574
Watanabe classification
I	21	11
II	7	10
III	1	0
Symptom pre-surgery
pain	19	7s
locking	1	2
limited ROM	9	4
swelling	4	3
snapping	9	5
Follow-up (y)	4.45±2.90(1-10)	3.91±2.14(1-9)	0.471
Preoperative Ikeuchi score
excellent	0	1
good	14	12
fair	6	4
poor	9	4
Preoperative Lysholm score	71.58±6.85	72.83±9.35	0.444

Table 2. Clinical outcomes and self-evaluated outcomes at follow-up.

		Group 1	Group 2	p value
Symptoms at follow-up
the occurrence of symptom		11(37.93%)	4(26.67%)	0.467
pain
	after sports or long walk	9	10
	night pain	2	1
	cold or wet weather	2	2
	up & down stairs	0	2
	unclear reasons	3	0
locking		2	1
limited ROM		5	8
swelling		0	0
snapping		6	8
Sporting event
basketball		3	1
rope skipping		3	0
running		11	6
no participation in sports		5	4
Postoperative Ikeuchi score
excellent		16	10
good		8	4
fair		3	5
bad		2	1
Postoperative Lysholm score of the asymptomatic side		90.86±8.25	92.61±8.68	0.287
Postoperative Lysholm score of the symptomatic side		91.38±8.90	95.33±7.18	0.146

No competing interests reported.

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Comparison between conservative and prophylactically concurrent meniscoplasty on the asymptomatic knee in children with bilateral DLM: a retrospective study

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Abstract

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Methods

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Discussion

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