Fifteen-year follow-up of arthroscopic partial meniscectomy

From an original pool of 283 patients, 146 patients who had undergone arthroscopic partial meniscectomy an average of 14.7 years before were followed-up. Lysholm score, Tegner activity level, satisfaction index on a scale of 1 to 10, and standing anteroposterior and flexion weight-bearing radiographs of both knees, were obtained. A physical examination was performed on each knee emphasizing motion, swelling, and ligament evaluation. Radiographs were graded for degenerative changes for each knee. Each knee joint space was also measured in millimeters and compared, operative knee with unoperated knee. The unoperated knee had no injuries or surgeries and was used as a control. Patients were 83% male and 17% female; 78% had undergone medial meniscectomies, 19% lateral, and 3% both. There were 88% good and excellent results in anterior cruciate liagment—stable knees. The radiographic grade side-to-side difference showed the operative knee to be only a 0.23 grade worse than the nonoperative knee. Age at the time of meniscectomy was not found to be a factor. Male patients had better radiographic results than female patients, but not better functional scores. Medial meniscus and lateral meniscus results were not significantly different. Knees with a femoral-tibial anatomic alignment of >0° valgus compared with ≤0° and that had undergone medial meniscectomy had significantly better radiographic results. Patients with anterior cruciate ligament tears and meniscectomy did significantly poorer than stable knees with meniscectomy in regards to radiographic grade change, Lysholm, satisfaction index, Tegner level, and medial joint space narrowing.     

Reconstruction of the chronically insufficient anterior cruciate ligament with the central third of the patellar ligament

The results of reconstruction of the anterior cruciate ligament with the central third of the patellar ligament as a free, autogenous, non-vascularized graft were retrospectively reviewed at our institution. Eighty reconstructions in seventy-nine patients were evaluated after a minimum of two years. In forty-eight (60 per cent) of the knees, the reconstruction was augmented with an extra-articular lateral sling of iliotibial band. The patients were evaluated with a physical examination, a KT-1000 arthrometer, radiographs, a subjective questionnaire, and a revision of the scale of The Hospital for Special Surgery for rating ligaments. Postoperatively, seventy-six (95 per cent) of the eighty knees no longer gave way, and the pivot-shift test was negative in sixty-seven (84 per cent) of the knees. The average score on the ligament-rating scale was 93 points. All of the patients who had clinical instability at the time of the most recent follow-up had associated ligamentous instability that had not been appreciated or addressed at the time of reconstruction. Arthrometric evaluation revealed that the laxity differed by three millimeters or less from that of the untreated knee in sixty (76 per cent) of the treated knees. In the patient who had bilateral reconstruction, the laxity was the same in both knees. Seventeen patients, who had more than three millimeters of translation, also had additional related ligamentous instability, most commonly posterolateral instability and insufficiency of the medial collateral ligament. We think that major associated ligamentous instability predisposes the reconstruction to failure and should be corrected in conjunction with the reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ultrasonographic findings in knee osteoarthritis: a comparative study with clinical and radiographic assessment

OBJECTIVE: To compare ultrasonographic (US) findings with clinical and radiographic assessment in knee osteoarthritis (OA). METHODS: Fifty patients with primary knee OA were studied. Clinical assessment of both knees was performed by the same rheumatologist who recorded a visual analogue scale (VAS) for pain (VASP). All patients underwent a US examination of their knees by a second blinded rheumatologist. Weight-bearing anteroposterior and lateral knee radiographs were read by a third blinded rheumatologist who assessed the Kellgren and Lawrence (K-L) grade, the femorotibial (FT) space width and the presence of patello-femoral degenerative signs. RESULTS: Forty patients had bilateral symptomatic knee OA and 10 unilateral symptomatic OA. All knees showed radiographic FT degenerative signs. US findings in symptomatic knees were effusion (47%), protrusion of the medial meniscus (MMP) with displacement of the medial collateral ligament (MCLD) (61%) and Baker's cyst (22%). US effusion, MMP and MCLD were associated with a significantly higher VAS score for pain (P<0.05). MMP was associated with medial FT space width (P<0.05). Patients who had a difference between VAS score for pain in each knee greater than 30 (28 patients) showed significantly more unilateral effusion, MMP, MCLD and worse K-L grade in the more symptomatic knee than those with a difference lesser than 30 (22 patients). CONCLUSION: Knee effusion and MMP with MCLD are associated with pain in knee OA. In addition, MMP may contribute to the radiographic medial FT space narrowing. We propose US for assessing periarticular and intraarticular abnormalities involved in the pathophysiology of knee OA.     

Bone-patellar ligament-bone and fascia lata allografts for reconstruction of the anterior cruciate ligament

A prospective study was performed of the first forty-seven consecutive patients who had repair of a ruptured anterior cruciate ligament and replacement with an allograft. Patients who had a rupture of another ligament were excluded, to provide a homogeneous group. Twenty-two patients received a fascia lata allograft and twenty-five patients received a bone-patellar ligament-bone allograft. All patients were enrolled in an exercise program to facilitate motion of the knee immediately after the operation, and all patients returned for postoperative evaluation (mean, forty months; range, twenty-five to sixty-seven months). The results were based on a comprehensive subjective and objective rating system, which assessed twenty factors. On testing with the KT-1000 arthrometer, 69 per cent of the patients had less than three millimeters of increased anterior-posterior displacement of the knee that had been operated on compared with the contralateral knee, 26 per cent had three to five millimeters, and 5 per cent had more than five millimeters. The knees that had a bone-patellar ligament-bone allograft had significantly lower values for anterior-posterior displacement than did those that had a fascia lata allograft (p less than 0.05). Just one patient, the only one in whom the fascia lata graft failed, had giving-way. There were no infections, and there was no evidence of rejection of the allograft or documented transmission of disease at the time of writing. A strict rating system was used. Eighteen patients (38 per cent) had an excellent result, twenty-four (51 per cent) had a good result, and five (11 per cent) had a fair or poor result. Motion of the knee immediately postoperatively was not deleterious to the allograft, and, because limitations of motion were identified and treated in the early postoperative period, full motion (0 to 135 degrees) was restored in all knees.     

Comparison of Kneelax and KT-1000 knee ligament arthrometers

Two commercially available knee ligament arthrometers (KT-1000 MEDmetric Corporation, San Diego, California and Kneelax MR Systems, Haarlem, The Netherlands) were used to measure anterior tibial translation. In this study 91 subjects with no history of knee pathology were tested using both devices. Both normal knees were tested and comparison of recorded anterior translation (millimeters) was performed. Absolute numbers at forces of 67N, 89N, 134N, and manual maximum displacements were recorded. Side-to-side differences were calculated and data were compared. There was a significant difference found between the absolute values of each device. The KT-1000 was found to record greater values in millimeters of translation. Although the absolute values were significantly different, the side-to-side differences were not significantly different between devices.     

Evaluation of an electrogoniometric instrument for measurement of laxity of the knee

Eight lower extremities from cadavera were tested for anterior-posterior laxity in two positions before and after transection of the anterior cruciate ligament. At critical points in the tests, electrogoniometric and radiographic measurements of tibiofemoral translation were compared. By direct measurement, we determined the accuracy of the radiographic method to +/- 0.4 millimeter (95 per cent) in measuring anterior-posterior translations of the tibia with respect to the femur. The electrogoniometer estimated displacement of the tibia with respect to the femur during the anterior drawer test to be 3.5 +/- 8.2 millimeters at 90 degrees of flexion of the knee and 11.1 +/- 16.1 millimeters at 30 degrees of flexion. Direct comparison of these measurements with those obtained by means of the radiographic technique showed that the electrogoniometer tended, on average, to overestimate the tibial translation. The amount of overestimation was 0.7 millimeter for intact knees and 1.9 millimeters after sacrifice of the anterior cruciate ligament. Despite this small average error in measurement of tibial translation, the difference between individual electrogoniometric and radiographic measurements varied greatly, with a 95 per cent confidence limit of +/- 5.5 millimeters. The error of the electrogoniometric measurements varied with the angle of flexion of the knee during testing, both the accuracy and the reliability of the electrogoniometric measurements being greatly diminished at 30 degrees of flexion. The electrogoniometric method also tended to overestimate tibial internal rotation (by an average of 10.5 degrees) and external rotation (by an average of 9.3 degrees); the reliability of these measurements was +/- 6.9 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)     

Arthrometric evaluation of knees that have a torn anterior cruciate ligament

We used the KT-1000 arthrometer to test the knees of 107 patients who had an acute tear of the anterior cruciate ligament, 153 patients who had a chronic tear, and 141 control subjects, for a total of 401 individuals. The three testing parameters were the extent of anterior translation at eighty-nine newtons of force and at maximum manual force, and the compliance index. The differences between the involved and the uninvolved knees were calculated. At eighty-nine newtons, all but one of the control subjects had anterior translation of ten millimeters or less, compared with 58 per cent of the patients who had a chronic tear. At maximum manual force, all but two of the control subjects had translation of ten millimeters or less, compared with 20 per cent of the patients who had an acute or a chronic tear. Analysis of variance showed that the clinical diagnosis correlated well with the results for all tests (p less than 0.001). However, when the uninjured knees of patients who had an acute or a chronic tear were compared with the knees of the control subjects, significant differences were noted (p less than 0.001 to 0.006). In the patients who had a chronic tear, there was no relationship between the time from injury to operation and the extent of anterior translation. The arthrometric test at maximum manual force was the strongest discriminant; it differentiated normal from abnormal knees (p less than 0.001) with high sensitivity (92 per cent), high specificity (95 per cent), and high positive predictive accuracy; the cut-off point was eleven millimeters or less.(ABSTRACT TRUNCATED AT 250 WORDS)     

Posterior cruciate ligament replacement with a two-strand quadriceps tendon-patellar bone autograft and a tibial inlay technique

BACKGROUND: Complete ruptures of the posterior cruciate ligament alter knee kinematics and may result in functional limitations with sports and daily activities. We prospectively evaluated the functional results and knee stability after posterior cruciate ligament replacement with use of a two-strand quadriceps tendon-patellar bone autograft and a tibial inlay technique. METHODS: Nineteen patients were followed for a mean of thirty-five months postoperatively. All had a chronic knee injury, and eight had additional ligament reconstructions. The results were measured with stress radiography, arthrometric testing, and two validated knee-rating instruments. RESULTS: Eighteen patients rated the knee condition as improved. Before surgery, eleven patients had pain with daily activities, but only one had such pain at the time of the latest follow-up. Significant improvements were noted for pain, swelling, giving-way, walking, climbing stairs, squatting, running, jumping, and twisting and turning (all p < or = 0.05). Eleven patients returned to low-impact sports, and two patients were able to participate in strenuous sports without problems. At the time of the latest follow-up, stress radiography revealed that fourteen knees had < or =5 mm of increased posterior tibial translation between the reconstructed and the contralateral side, three knees had 6 to 10 mm, and two knees had >10 mm. No knee had an infection, permanent limitation of knee motion, or patellar fracture. CONCLUSIONS: Posterior cruciate ligament replacement produced reasonable subjective, functional, and objective results in this group of complex, chronic knee injuries. The tibial inlay approach was useful in nine revisions in which prior tibial tunnels had to be avoided.     

Medical restraints to anterior-posterior motion of the knee

We investigated the motion of cadaver knees before and after section of the medial structures and anterior cruciate ligament. The knees were tested using a 5-degrees-of-freedom in vitro knee-testing apparatus that measured anterior-posterior, medial-lateral, and axial displacement as well as internal-external and valgus-varus rotation. The flexion angle could be varied but was fixed for each individual test. A 125-newton anterior-posterior force was applied perpendicular to the tibial shaft and the resulting motion of the knee was measured. In five knees the anterior cruciate ligament was cut first, followed by progressive cuts of the structures on the medial side (superficial medial collateral ligament, deep medial ligament, oblique fibers of the superficial medial ligament, and the posteromedial part of the capsule). Conversely, in five knees the medial structures were progressively cut first, followed by section of the anterior cruciate ligament. Tests were performed after each cut. With an intact anterior cruciate ligament, progressive cutting of the medial side had no effect on anterior and posterior displacements. When section of the medial structures followed cutting of the anterior cruciate ligament, anterior displacement exceeded that seen after isolated section of the anterior cruciate ligament. The anterior and posterior load-tests were repeated with the tibia fixed in 5 degrees of internal and 5 degrees of external rotation. Fixed external rotation had no effect on anterior and posterior displacements. Fixed internal rotation significantly decreased anterior displacement only when both the anterior cruciate ligament and the medial structures were cut.(ABSTRACT TRUNCATED AT 250 WORDS)     

应力后沉征诊断单纯后交叉韧带损伤

目的　对 18例经手术证实为急性单纯后交叉韧带损伤行应力下胫骨后移的定量分析 ,以评价应力后沉征在诊断后交叉韧带损伤中的作用。方法　术前在麻醉和屈膝 90°行双膝应力 (15kg)下的摄片并定量分析 ,得出双膝应力前后的胫骨后移情况。结果　患膝较健侧有明显的胫骨后移 ,患膝应力下平均胫骨后移较非应力下提高 1+级。结论　在诊断急性后交叉韧带损伤时 ,麻醉下和屈膝 90°位应力后沉征较后沉征和后抽屉试验准确和灵敏 ,应力摄片示胫骨后移有明显意义的升高。要理解屈膝 90°位和麻醉下行后沉征和后抽屈试验的重要性     

Acute hemarthrosis of the knee: indications for diagnostic arthroscopy

The objective of this study was to define the role of early diagnostic knee arthroscopy for patients with an acute knee injury and hemarthrosis. Forty-five patients with an acute knee injury followed by a posttraumatic hemarthrosis during a 1-year period were prospectively reviewed. All patients were evaluated preoperatively followed by examination under anesthesia and arthroscopy of the knee. The majority of patients, 32 (71%), had an anterior cruciate ligament tear. Meniscal tears occurred in 21 patients (47%). Meniscal tears requiring surgery occurred in only 10 of 25 meniscal tears (40%). Seven patients (16%) had medial collateral ligament and/or posteromedial capsular sprain. Eight patients (18%) had an osteochondral fracture or patellar dislocation associated with an osteochondral fracture. The majority of knees with a torn meniscus or osteochondral fracture had an anterior cruciate ligament tear. Clinically, 18 of 21 knees (86%) with an acute complete anterior cruciate ligament tear were diagnosed preoperatively with the Lachman test. The Lachman test conducted with patients under anesthesia was positive for 19 of 21 knees (90%) with an acute complete anterior cruciate ligament tear. The preoperative examination correctly identified six of seven knees (86%) with a medial collateral ligament sprain. The preoperative Lachman test was positive in only two of five knees (40%) with a partial anterior cruciate ligament tear. The Lachman test with patients under anesthesia was positive for four of five knees (80%) with an acute partial anterior cruciate ligament tear. Preoperative examination yielded the correct diagnosis in only 9 of 21 knees (43%) with a meniscal tear and 1 of 6 knees (17%) with an osteochondral fracture.(ABSTRACT TRUNCATED AT 250 WORDS)     

Kinematics after tear in the anterior cruciate ligament: dynamic bilateral radiostereometric studies in 11 patients

We studied the kinematics of both knees using radiostereometry in 11 patients with unilateral injury of the anterior cruciate ligament and normal contralateral knee. Continuous radiostereometric exposures at a speed of 24 exposures a second were performed, when the patients ascended an 8 cm high platform. The tibial center was more dorsally displaced and the tibia more externally rotated on the injured side. This increasing external tibial rotation was associated with increased anterior displacement of the lateral femoral condyle. The latter also displayed less anterior-posterior translations during continuous extension. The anterior-posterior translation of the medial condyle was about the same as on the uninjured side. Changes in the kinematics of the knee joint due to rupture of the anterior cruciate ligament can result in an abnormal joint load, which may increase the risk of damage to the cartilage and the menisci.     

Early expression of marker genes in the rabbit medial collateral and anterior cruciate ligaments: the use of different viral vectors and the effects of injury.

Gene therapy is a technique that may offer advantages over current methods of cytokine delivery to ligaments. To determine if implanted genes could be expressed in normal and injured knee ligaments, the medial collateral ligament and anterior cruciate ligament were studied in 18 rabbits. A retroviral ex vivo technique using allograft medial collateral ligament and anterior cruciate ligament fibroblasts and an adenoviral in vivo technique were compared as methods for delivering the LacZ marker gene to knee ligaments. Bilateral knee surgeries were performed, and the rabbits were equally divided into three groups. Group 1 received the retrovirus and the medial collateral ligament was ruptured, Group 2 received the adenovirus and the medial collateral ligament was ruptured, and Group 3 received the adenovirus and the medial collateral ligament was not injured. The anterior cruciate ligament was not injured in any group. The medial collateral and anterior cruciate ligaments of the right knees received 10(6) allografted, transduced ligament fibroblasts or 10(9) adenovirus particles, whereas the ligaments of the left knee received a similar volume of saline solution only. Equal numbers of rabbits were killed at 10 days, 3 weeks, and 6 weeks following the procedure. Ligament samples were stained with X-gal to detect the expression of the LacZ gene product, beta-galactosidase. LacZ gene expression was evident in ruptured and uninjured medial collateral ligaments as well as in the anterior cruciate ligament. The expression lasted between 10 days and 3 weeks in the medial collateral and anterior cruciate ligaments with use of the retrovirus and between 3 and 6 weeks in the medial collateral ligament and at least 6 weeks in the anterior cruciate ligament with the adenovirus. The length of gene expression in the ruptured and uninjured medial collateral ligaments did not differ. These preliminary studies indicate that gene transfer to normal and injured knee ligaments is possible.     

Kinematics after tear in the anterior cruciate ligament: Dynamic bilateral radiostereometric studies in 11 patients

We studied the kinematics of both knees using radiostereometry in 11 patients with unilateral injury of the anterior cruciate ligament and normal contralateral knee. Continuous radiostereometric exposures at a speed of 2-4 exposures a second were performed, when the patients ascended an 8 cm high platform. The tibial center was more dorsally displaced and the tibia more externally rotated on the injured side. This increasing external tibial rotation was associated with increased anterior displacement of the lateral femoral condyle. The latter also displayed less anterior-posterior translations during continuous extension. The anterior-posterior translation of the medial condyle was about the same as on the uninjured side. Changes in the kinematics of the knee joint due to rupture of the anterior cruciate ligament can result in an abnormal joint load, which may increase the risk of damage to the cartilage and the menisci.     

Kinematics after tear in the anterior cruciate ligament: Dynamic bilateral radiostereometric studies in 11 patients

We studied the kinematics of both knees using radiostereometry in 11 patients with unilateral injury of the anterior cruciate ligament and normal contralateral knee. Continuous radiostereometric exposures at a speed of 2-4 exposures a second were performed, when the patients ascended an 8 cm high platform. The tibial center was more dorsally displaced and the tibia more externally rotated on the injured side. This increasing external tibial rotation was associated with increased anterior displacement of the lateral femoral condyle. The latter also displayed less anterior-posterior translations during continuous extension. The anterior-posterior translation of the medial condyle was about the same as on the uninjured side. Changes in the kinematics of the knee joint due to rupture of the anterior cruciate ligament can result in an abnormal joint load, which may increase the risk of damage to the cartilage and the menisci.     

Non-operative management of acute grade III medial collateral ligament injury of the knee: a prospective study

In a prospective study, 25 patients who had acute complete rupture of the medial collateral ligament of the knee with associated anterior cruciate ligament injury were treated by cast bracing and physiotherapy. Their average age was 27.6 years (range 15-53 years) with average follow-up of 24.2 months (range 12-48 months). All 25 patients had good or excellent results, with return to the pre-injury level of sporting activities by 1 year and with restoration of medial stability. This study shows that conservation treatment of this injury can restore stability to the medial side of the knee, even in the presence of anterior cruciate ligament damage.     

Instrumented measurement of in vivo anterior-posterior translation in the canine knee to assess anterior cruciate integrity.

This study was designed to objectively quantify in vivo anterior-posterior canine knee translation relative to anterior cruciate ligament (ACL) integrity. Tibial translation was determined in one knee of 43 crossbreed hounds from radiographs performed while a set anterior and then posterior force was applied to the tibia using a custom designed device. The total (TTT), anterior (ATT), and posterior (PTT) tibial translation were measured (absolute) and normalized to the width of the tibia (normalized). Absolute and normalized TTT was significantly greater in ruptured ACL knees than in partially disrupted (PD) ACL knees, which were significantly greater than in intact ACL knees. ATT and PTT was significantly greater in ruptured ACL knees than in PD or intact ACL knees, which were not significantly different. The sensitivity and specificity of normalized TTT to distinguish knees with intact from PD ACLs were both 100%. Normalized TTT to distinguish knees with PD from ruptured ACLs had a sensitivity and specificity of 100% and 92%, respectively. Intra- and inter-observer intra-class correlation coefficients were 0.84 or higher for all translations. This precise non-invasive technique to assess canine knee translational stability and ACL integrity permits repetitive, objective measurements for diagnostic use and to assess therapeutic intervention efficacy.     

Healing of the rabbit medial collateral ligament following an o'donoghue triad injury: Effects of anterior cruciate ligament reconstruction

The effects of healing time and anterior cruciate ligament reconstruction on healing of the medial collateral ligament and stability of the knee joint were evaluated in a rabbit model of an O'Donoghue triad injury (rupture of the medial collateral ligament with removal of the anterior cruciate ligament and part of the medial meniscus). At time 0 and at 6 and 12 weeks postoperatively, the anterior-posterior translation and varus-valgus rotation of the knee, the structural properties of the femur-medial collateral ligament-tibia complex, and the mechanical properties of the substance of the medial collateral ligament were evaluated. Although anterior-posterior translation increased significantly with time, we could not demonstrate a significant temporal effect on varus-valgus rotation. The ultimate load, elongation at failure, and energy absorbed to failure improved with time. In addition, with time, failure of the complex occurred more often in the ligament substance than at the osseous insertion. Because healing time did not affect the cross-sectional area or modulus of the medial collateral ligament, the improved structural properties of the complex resulted not from improvements in the mechanical properties of the tissue but rather from healing of the tibial insertion site. By 12 weeks, the reconstructed knees had only minor signs of osteoarthrosis on the tibiofemoral surfaces; this is in contrast to the findings in anterior cruciate ligament-deficient knees in our earlier study. Initially, reconstruction also improved stability of the knee. Additionally, at 12 weeks, the stiffness of the complexes from the reconstructed group was 1.3 times that of the anterior cruciate ligament-deficient group (p < 0.05), and the ultimate load had increased by a factor of 1.6 (p < 0.05). Our findings demonstrate that reconstruction of the anterior cruciate ligament in the rabbit helps to stabilize the joint, improves healing of the medial collateral ligament, and may decrease the incidence of early-onset osteoarthrosis after an O'Donoghue triad injury.     

The use of a modular rotating hinge component in salvage revision total knee arthroplasty

Revision total knee arthroplasty (TKA) using a second-generation modular rotating hinge design was performed on 16 knees in 15 patients over a 5-year period. Follow-up of 2 to 6 years (mean, 51 months) was obtained in 14 knees in 13 patients. Indications for revision were aseptic loosening of a hinged prosthesis (8 knees), loosening and bone loss associated with chronic extensor mechanism disruption (2 knees), component instability with chronic medial collateral ligament disruption (3 knees), and comminuted distal femur fracture (1 knee). Clinical and radiographic results were reviewed and compared with 87 patients who underwent revision TKA using a standard condylar revision design during the same period. Early results showed comparable postoperative knee scores and range of motion between the 2 groups despite the use of the rotating hinge component in more complex revision cases. No patient has exhibited radiographic evidence of definite component loosening. Alignment of 5 degrees to 10 degrees of valgus in the frontal plane and within 2 degrees of neutral in the sagittal plane was achieved consistently. Short-term clinical and radiographic results are encouraging and suggest that a second-generation modular rotating hinge component can be used successfully in selected salvage revision cases.     

Unicompartmental knee replacement: a comparison of constrained and unconstrained designs.

Seventy-six patients who had eighty-seven unicompartmental knee replacements were followed for an average of fifty-three months (range, two to twelve years). The operation was on the medial side in eighty-two knees and on the lateral side in five. Fifty replacements were unconstrained and thirty-seven were constrained. Of the fifty knees that had an unconstrained replacement, forty-nine (98 per cent) had a good or excellent result, compared with only twenty-six (70 per cent) of the knees that had a constrained replacement; the difference is significant (p = 0.0007). No knee that had an unconstrained replacement had a poor result, compared with nine (24 per cent) of the knees that had a constrained replacement (p = 0.0009). Four (8 per cent) of the fifty knees that had an unconstrained replacement later had a revision total knee arthroplasty, compared with ten (27 per cent) of the thirty-seven knees that had a constrained replacement; the difference is significant (p = 0.04). Noteworthy degenerative changes in the opposite compartment occurred in only one of the eighty-seven knees (a knee in which an unconstrained prosthesis had been inserted).