ME_HOSER

TEN YEAR FOLLOW UP
OF ARTHROSCOPIC PARTIAL LATERAL MENISCECTOMY
Christian Hoser, Clayton Brown, John Bartlett, Christian Fink

Univ.-Klinik für Unfallchirurgie, Universität Innsbruck, Anichstr. 35, A-6020 INNSBRUCK, AUTRICHE

I. Introduction

The function of the menisci in load transmission, stability and articular cartilage nutrition has been established in the 1970s and earlier. Although it has been suspected for a long time Walker et al were able to prove that the menisci transmit load across the joint.

It has been stated that the meniscus transmits between 30 and 70 % of weightbearing load. Kurosawa showed that total meniscectomy reduced the surface contact area by a third to a half in full extension which supports the study of Walker. He stated that total medial meniscectomy reduces the contact area from 6 to 2 cm2. Kurosawa reports that the peak contact stress at the center of the load bearing area rises from 30 or 40 kg/cm2 (10 kg/cm2 equal 1 MegaPascal.) in the intact knee to 70 or 80 kg/cm2 in the meniscectomized knee at a load of 1500 Newton.

Morrison determined the mean maximum joint force during level walking to be 3 times body weight, which results in a force of 2100 N for a person of 70 kg.

Cox and Cordell established the relationship between meniscectomy and consequential osteoarthritis in a dog model. He found the worst changes in meniscectomized knee joints followed by displaced bucket handle and flap tears, which got trapped in between the condyles. No or minimal changes were found in joints with healed menisci and those tears not interfering with joint motion.

Many reports have been written about results after open or arthroscopic, partial or total meniscectomies.

The convex shape of the lateral tibial plateau leads to poor congrueny of tibia and femur as soon as the meniscus is lost, which is a major difference between medial and lateral comparment.

Furthermore Walker stated that the lateral meniscus carried most of the load in the lateral compartment wheras the load was shared between exposed cartilage and meniscus on the medial side.

There is evidence in the literature that the lateral compartment is more susceptible to degenerative changes than the medial compartment. Johnson states in his conclusion in 1974 that results are better after medial than after lateral meniscectomy.

Based on the above information we designed a study with a homogenous patient population to be able to answer the following question :

What is the long term outcome of patients who had undergone partial lateral arthroscopic meniscectomy with no other pathology detected in the knee.

II. Material and Methods

In the years 1983-1985 the senior author (JB) performed 85 arthroscopic partial lateral meniscectomies in the otherwise normal knee. 65 of these patients could be located and 43 were still living in the greater Melbourne area with less than two hours travel time to the examination site.

35 patients with 37 knees were initially examined ; however, the patient population was refined to include only those patients with isolated lateral meniscal pathology, and no evidence of chondral damage or ligamentous insatbility, at the time of the index procedure. On these assumptions, 28 patients with 30 knees were reviewed. Prior to examination, all patients were asked to complete the Cincinnati knee examination questionnaire, and each patient subsequently brought the results of this questionnaire to the examination appointment. The questionnaire provides an evaluation of knee function as it relates to pain, swelling, giving way, pain on activity or stair climbing, or pain with more vigorous activity such as running or jumping. Frequency of pain was assessed, as were mechanical symptoms of locking or grinding. The maximum score is 100 points. All patients were examined by two of us (CH and CB). This included a thorough knee examination, with special emphasis on stability and alignment. Range of motion was recorded, and the presence or absence of effusion. By asking the patient we tried to find out if there was a significant trauma preceeding the onset of symptoms. If there was a trauma in the history we called it a traumatic tear and otherwise degenerative. At the time of examination, each patient`s chart was looked through to determine the crossectional area of the resected part of the meniscus from a detailed diagrammatic description done by the senoir author on the operation report. The meniscus defect was calculated by measuring central-peripheral and antero-posterior defects subdivided into one-thirds. This gave the resected crossectional area in ninths of the total meniscal area. Furthermore the chart contained detailed information on x-ray changes prior to surgery. All patients with changes were excluded. All patients had a thirty degree postero-anterior flexion weightbearing view of the affected knee performed. This view shows the lateral compartment cartilage space to be a little larger than the medial, and is more sensitive to any narrowing than a supine antero-posterior radiograph. Intercondylar osteophytes are also visualized, which are hard or impossible to detect			on the antero-posterior film. As a second plane a standard lateral x-ray was taken. Radiographic changes were assessed and tabulated in two ways. Classification used by Tapper et al. based on Fairbanks`s description : • Grade 0 : normal • Grade 1 : squaring of the tibial margin • Grade 2 : flattening of the femoral condyle and squaring and sclerosis of the tibial plateau • Grade 3 : narrowing of the joint space or hypertrophic changes or both • Grade 4 : all of these to a more severe degree. Additionally the presence and location of osteophytes was recorded and tabulated. Both medial and the affected lateral compartment were graded. The radiologic changes were classified in a blinded fashion by two of us (C.H and C.B.) to reduce interobserver error. Statistical analysis was performed to find out if age, etiology (degenerative ; traumatic), reoperation, gender, duration of preoperative symptoms, alignment had an influence on the functional and radiographic outcome. III. Results The mean follow up was 10.3 years (9.2-12.1 years). The mean age at time of assessment was 32 years (24-79 years). 23 patients were male. 12 (40 %) lateral meniscal tears were traumatic, the remainder being degenerative. The largest number of traumatic tears (42 %) were incurred as the result of Australian Rules Football. There was a wide range of meniscal pathology, which included cystic tears, discoid tears, either longitudinal, radial or horizontal ; bucket handle tears or radial tears. To clinical examination, 63 % of patients (n=19) had normal alignment and 37 %(n=11) had a detectable increased valgus in the operated knee. 26 (93 %) had no effusion and 3 knees (10 %) had a flexion deficit. Two of these knees had a contracture of 5 degrees and one had a contracture of 10 degrees. There was no knee with an extension deficit. Of the 100 points available on the Cincinnatti questionnaire patients averaged 78.7+15.9.

	*1. Meniscus defect after resection*	scores there was no difference between both groups. *4. Second operation* 30 % (9 patients) had another procedure performed addressing symptoms in the lateral compartment. Patients who needed a second procedure (n=9) had significantly worse results (67.7+19.0) in the Cincinnatti score than those who did not (n=21) (83.9+11.3) p=0.004 two tailed t-test. Radiologic changes showed a strong trend with a mean of 2.4+1.0 for the reoperated group and 2.0+0.9 (p=0.2) for the others. IV. Discussion The vast majority of studies on meniscectomy report short or medium term results up to five years. Long term results were presented by Streli et al. He examined 82 patients 18 to 25 years after open partial meniscectomy but fails to distinguish between medial and lateral side. He reports 74 % excellent results and concludes that partial open meniscectomy is a benign procedure. Johnsons study included patients from 5 to 37 years postoperatively and associated lesions to other structures in the knee. In a very strict analysis he reports 57 percent unsatisfactory results. Additionally he mentions that patients with lateral meniscectomy did worse than those with medial meniscectomies. Tapper et al found that 45 % of males and only 10 % of females were symptom free after open meniscectomy, not excluding patients with additional pathology in the knee. Rangger et al used a.p. supine x-rays for evaluation 53.5 months after arthroscopic meniscectomy. In their subgroup of lateral meniscectomies with no chondral damage at surgery (n=12) they found no changes in 75 % of patients and no patient showed joint space norrowing. The latter may be due to not performing weightbearing x-rays. Looking at our results, we must conclude that there is a major increase in the development of radiographic changes between 5 and 10 years postoperatively.


*2. Area* 1/9 1 2/9 6 3/9 1 4/9 12 6/9 10 18 (60 %) had a meniscus defect in the anteroposterior diameter of two thirds. In the radial diameter, 22 (73 %) also had two thirds defect. As can be seen from these figures, 22 knees (73 %) had a crossectional area of meniscus resection greater than one third of the total meniscus. Of the 30 knees available for examination, only 9(27 %) had grade 0 (1) or 1 (8) changes according to Tapper et al. 9 had grade 2 changes, 11 grade 3, and 1 grade 4 changes. Medial compartment 25 had grade 1 and 5 had grade 0. Radiologically 18 (60 %) had normal lateral cartilage space, 6 patients (20 %) had one third narrowing, 4 (13 %) had two thirds narrowing and 2 (7 %) had total loss of lateral cartilage space. Osteophytes were located on the intercondylar side of the lateral femoral condyle in 21 patients (70 %), and the lateral margin of the lateral femoral condyle in 5 patients (17 %). On the intercondylar side of the lateral tibial condyle 4 knees (13 %) and on its lateral margin 11 knees (36 %) showed osteophyte formation. Only 6 (20 %) knees were radiologically normal. *3. Etiology* There was no statistically significant difference between traumatic (n=21) and degenerative (n=9) tears with radiologic changes. In the Cincinnatti

Maletius et al in a 12-15 year follow up study of pooled medial and lateral arthroscopic partial meniscectomies could show that 30 % of patients with minimal chondral changes at surgery (n=20) showed joint space narrowing on weightbearing films, whereas the unaffected knees showed a 15 % incidence. They stated that chondral damage at the time of meniscal surgery and age over 30 year lead to a major increase of degenerative changes. Jaureguito followed 20 patients (21 knees) clinically and radiographically 5.5 to 11 years after arthroscopic partial lateral meniscectomy. 55 % of knees showed joint space norrowing wheras 38 % showed no Fairbank changes at all. In a comparison of affected and unaffected knees (n=19) there was only a minor difference with 45 % normal x-rays for the operated side and 56 % for the nonoperated side. They state, that in a lot of		cases it was hard tell the side of meniscectomy by the bone radiologist. Fauno et al followed 136 patients after unilateral arthroscopic meniscus resection of isolated mensical tears 8 to 11 years postop not excluding patients with chondral damage. 15 of 19 (79 %) knees showed Grade 1 or more Fairbank changes. They emphasized that malalignment increased the risk for subsequent degenerative changes dramatically. Some studies tried to identify risk factors. Maletius et al stated that age was a major predictor for the outcome. Over 40 year old patients had much worse results. We also could find that the age influences the results but not such a great extent. In conclusion we state that we have to accept a high incidence of osteoarthritis after arthroscopic partial lateral meniscectomy in the long run. Suturing the ruptured meniscus should therefore always be done if possible.

BIBLIOGRAPHY
ALLEN P.R., DENHAM, R.A., SWAN A.V. Late degenerative changes after meniscectomy. J. Bone Joint Surg. [Br] 66-B : 666-671, 1984. COX J.S., CORDELL L.D. The degenerative effects of medial meniscus tears in dogs`knees. Clin. Orthop. 125 : 236-242,1977. COX J.S., NYE C.E., SCHAEFER W.W., WOODSTEIN I.J. The degenerative effects of partial and total resection of the medial meniscus in dogs knees. Clin. Orthop. 109 : 178-183, 1975. FAUNO P., NIELSEN A.B. Arthroscopic partial meniscectomy : A long-term follow-up. Arthroscopy 8(3) : 345-349, 1992. JAUREGUITO J.W., ELLIOTT, J.S., et al. The effect of partial lateral meniscectomy in an otherwise normal knee : A retrospective review of functionla, clinical, and radiographic results. Arthroscopy 11 : 29-36, 1995.	JOHNSON R.J., KETTELKAMP D.B., CLARK W., LEAVERTON P. Factors affecting late results after meniscectomy. J. Bone Joint Surg. [Am] 56 : 719-729, 1974. KUROSAWA H., FUKUBAYASHI T., NAKAJIMA H. Load-bearing mode of the knee joint. Clin. Orthop. 149 : 283-290, 1980. MALETIUS W., MESSNER K. The effect of partial meniscectomy on the long term prognosis of knees with localized, severe chondral damage. A Twelve to fifteen-year followup. Am J. Sports Med. 24 : 258-262, 1996. MORRISON, J.B. Bioengineering analysis of force actions transmitted by the knee joint. Med. Biol. Eng. 4 : 573, 1969.		Rangger, C., Klestil, T., Glötzer W., et al. Osteoarthritis after arthroscopic partial meniscectomy. Am J. Sports Med. 23 : 240-244,1995. STRELI R. Spaetergebnisse nach partieller Meniscusresektion in 82 Faellen (Nachuntersuchung nach 18-25 Jahren.). Der Unfallchirurg 26 : 97-103, 1955. TAPPER E.M., HOOVER N.W. Late results after meniscectomy. J. Bone Joint Surg. [Am] 51 : 517-526, 1969. WALKER, P.S., HAJEK,J.V. The load bearing areas in the knee joint. J. Biomech. 5 : 581,1972. WALKER, P.S., ERKMAN M.J. The role of the menisci in force transmission across the knee joint. Clin. Orthop. 109 :184-192, 1975.

TEN YEAR FOLLOW UP OF ARTHROSCOPIC PARTIAL LATERAL MENISCECTOMY Christian Hoser, Clayton Brown, John Bartlett, Christian Fink Univ.-Klinik für Unfallchirurgie, Universität Innsbruck, Anichstr. 35, A-6020 INNSBRUCK, AUTRICHE
I. Introduction The function of the menisci in load transmission, stability and articular cartilage nutrition has been established in the 1970s and earlier. Although it has been suspected for a long time Walker et al were able to prove that the menisci transmit load across the joint. It has been stated that the meniscus transmits between 30 and 70 % of weightbearing load. Kurosawa showed that total meniscectomy reduced the surface contact area by a third to a half in full extension which supports the study of Walker. He stated that total medial meniscectomy reduces the contact area from 6 to 2 cm2. Kurosawa reports that the peak contact stress at the center of the load bearing area rises from 30 or 40 kg/cm2 (10 kg/cm2 equal 1 MegaPascal.) in the intact knee to 70 or 80 kg/cm2 in the meniscectomized knee at a load of 1500 Newton. Morrison determined the mean maximum joint force during level walking to be 3 times body weight, which results in a force of 2100 N for a person of 70 kg. Cox and Cordell established the relationship between meniscectomy and consequential osteoarthritis in a dog model. He found the worst changes in meniscectomized knee joints followed by displaced bucket handle and flap tears, which got trapped in between the condyles. No or minimal changes were found in joints with healed menisci and those tears not interfering with joint motion.
		Many reports have been written about results after open or arthroscopic, partial or total meniscectomies. The convex shape of the lateral tibial plateau leads to poor congrueny of tibia and femur as soon as the meniscus is lost, which is a major difference between medial and lateral comparment. Furthermore Walker stated that the lateral meniscus carried most of the load in the lateral compartment wheras the load was shared between exposed cartilage and meniscus on the medial side. There is evidence in the literature that the lateral compartment is more susceptible to degenerative changes than the medial compartment. Johnson states in his conclusion in 1974 that results are better after medial than after lateral meniscectomy. Based on the above information we designed a study with a homogenous patient population to be able to answer the following question : What is the long term outcome of patients who had undergone partial lateral arthroscopic meniscectomy with no other pathology detected in the knee. II. Material and Methods In the years 1983-1985 the senior author (JB) performed 85 arthroscopic partial lateral meniscectomies in the otherwise normal knee. 65 of these patients could be located and 43 were still living in the greater Melbourne area with less than two hours travel time to the examination site.