Purpose. to evaluate the kinematics of a knee with a polyurethane meniscal scaffold for partial meniscus defect substitution during flexion under weightbearing conditions in an upright MRI. In addition, radial displacement and the surface of the scaffold was compared to the normal meniscus. Materials and Methods. One cadaver with a normal lateral meniscus and medial scaffold in the left knee and with a normal medial meniscus and lateral scaffold in the right knee. The scaffolds were implanted to substitute a 3 cm meniscus defect in the posterior horn. The cadaver was scanned in an 0,7T open MRI with a range of motion from 0-30-60-90 to hyperflexion. Kinematics were evaluated on sagittal images by the following two parameters: the position of the femoral condyle, identified by the centre of its posterior circular surface, which is named the flexion facet centre (FFC), and the point of closest approximation between the femoral and tibial subchondral plates, the contact point (CP). Both were identified in relation to the posterior tibial cortex. The displacement, measured on coronal images, is defined as the distance between the tibial plateau and the outer edge of the meniscus. The surface was also measured on coronal slices and contains the triangular surface of the meniscus. Results. Medially from 0 degrees to hyperflexion the FFC does not move anteroposteriorly. Laterally the FFC moves 12 mm backwards. The CP moves 15 mm backwards both lateral and medial. The lateral femoral condyle does roll-back with flexion but the medial does not, so the femur rotates externally around a medial centre. By contrast, both medial and lateral contact points move back, roughly in parallel, from 0 degrees to hyperflexion. The kinematics of the involved compartment is not influenced by the presence of the scaffold compared to the controlateral normal compartment. The radial displacement remains stable during full flexion: both the normal and scaffold meniscus have no different (p > 0,05) position. Both for the normal and the scaffold meniscus there is no difference (p > 0,05) in surface; there is no compression of the meniscus during flexion. Conclusion. The polyurethane implant, indicated for partial meniscus defect substitution, has no effect on the normal kinematics of the knee. Additionally, the degree of flexion has no effect on the external displacement, the surface and compressibility of both the implanted scaffold and the meniscus

INTRODUCTION. The purpose of this study is to report results from a prospective multicenter study of a bioresorbable type I collagen scaffold used to replace tissue loss following irreparable lateral meniscus injuries. METHODS. 49 non-consecutive patients (33M/16F; mean age 30.5 yrs, range 14.7–54.7 yrs) with irreparable lateral meniscus tears or loss requiring surgical treatment were prospectively enrolled at one of 7 EU centers. 11 patients (22%) had acute injuries of the lateral meniscus, while 38 (78%) had prior surgeries to the involved meniscus. Implantation of the LCMI (now Lateral Menaflex) was performed arthroscopically using an all-inside suturing technique (FASTFIX) combined with inside-out sutures in the more anterior meniscus aspect. Forty-three patients were evaluated with a 2 to 4-year follow-up (FU); mean FU duration was 45 months (range, 33–53 m). Patients were evaluated clinically and by self-assessment using Tegner activity and Lysholm function scores, as well as the Visual Analog Scales (VAS) for pain, and a satisfaction questionnaire. Evaluations were performed pre-operatively, 6 months, 1 year, 2 and 4 years after surgery. X-ray and/or MR-images were taken pre-operatively, and at 1 year and 2 years after surgery. RESULTS. At 3 months after surgery, all patients were able to return to activities of daily living without limitation. Post-op. mean values of all evaluated patients showed statistically significant improvement compared to the preoperative scores. Mean Tegner scores increased from 3.0 to 5.2 at 4 years (0.8 points less than the pre-injury “recall” value); mean Lysholm improved from 63 to 91; mean pain (VAS) decreased from 36 to 8. At the 4-year time point, 86% of the patients stated that they were satisfied with their results (compared to 78% at the one year FU time point). Function and pain scores improved continuously with the highest score at the latest FU evaluation. All data were statistically significant (p<0.001, except for Tegner with p=0.03). MRI examination revealed no changes to the articular cartilage and joint space; however, the newly formed tissue did not present a signal consistent with fully mature native meniscus tissue. Reoperations were necessary in 5 patients (10%) during the FU time period: 3 of the reoperations were for persistent swelling and pain, which were classified as related to the device (6%) and were treated by synovectomy and debridement. Patients recovered without sequelae. The re-op. rate in this series is comparable to re-op. rates reported after lateral meniscal repair. DISCUSSION. Based on available results with a minimum 2 year FU, 90% of the patients benefited from the Lateral Menaflex as evidenced by improved clinical outcomes associated with gains in activity and function. Longer-term FU continues to determine the extent and duration of the benefits observed

Purpose. to evaluate the radial displacement of meniscal allograft transplants (MATs) in patients operated with an open technique vs. an arthroscopic technique at 1 year postoperatively. Radial displacement or extrusion of the graft is frequently observed after meniscus transplantation. The hypothesis is that arthroscopically inserted MATs extrude less than open MATs and therefore have a more intra-articular position than open surgery transplants. Materials and Methods. 39 patients were included in the study: the first group of open surgery transplants consisted of 16 patients (10 lateral, 6 medial). The second group of arthroscopic transplants consisted of 21 patients (14 lateral, 7 medial). MR-images were taken one year post-surgery. The displacement, evaluated on 1,5T MR coronal images, was defined as the distance between the tibial plateau and the outer edge of the meniscus. Results. The radial displacement of lateral open surgery transplants (mean = 4,04 mm; SD = 1,46) is significantly larger (p < 0,05) than the displacement of arthroscopically implanted MATs (mean = 3,38 mm; SD = 0,85). The external displacement of medial open surgery transplants (mean = 4,71 mm; SD = 0,97) is significantly larger (p < 0,05) than the displacement of arthroscopically implanted MATs (mean = 2,36 mm; SD = 0,89). Conclusion. Graft position is influenced by the surgical technique; the radial displacement of arthroscopically implanted MATs is, both lateral and medial, significantly less than meniscal transplants implanted by open surgery. The clinical relevance remains to be determined

Purpouse. We hypothesized that patients receiving a medial collagen meniscus implant (MCMI) would show better clinical, radiograpich and Magnetic Resonanace Imaging (MRI) outcomes than patients treated with partial medial meniscectomy (PMM) at minimum 10 year FU. Material and Methods. Thirty-three non-randomized patients (males, mean age 40 years) were enrolled in the study to receive a MCMI (17 patients) or as control treated with a PMM (16 patients). All of them were clinically evaluated at time zero, 5 and minimum 10 years after surgery (mean FU 133 months, range 120–145) by Lysholm, VAS for pain, objective IKDC knee form and Tegner activity level. SF-36 score was performed pre-operatively and at final FU. Bilateral weight-bearing XRays were executed at time zero and at final FU. Minimum 10 years FU MRI images were compared with collected pre-operative MRI images by means of Yulish score. Genovese score was also used to evalute MCMI MRI survivorship. Results. MCMI group showed significantly lower VAS for pain (p = 0.0091), higher objective IKDC (p = 0.0026), Teger index (p = 0.0259) and SF-36 (p = 0.0259 for PHI and p = 0.0036 for MHI) scores compared with PMM group at minimum 10 year FU. Radiographic evaluation showed a significantly lower medial joint line height (p = 0.0002) and side-to-side difference (p = 0.0003) narrowing in MCMI group respect to PMM group at final FU. Discussion. Improvements in pain relief, activity level, objective IKDC score and joint-line preservation are detectable with the use of MCMI at a minimum 10 year FU. On the authors knowledge this is the first long-term controlled trial regarding this device, and our findings confirmed the mid-term good results achieved by Rodkey et al (1). Conclusions. This data support the use of meniscal scaffolds to treat irreparable partial meniscal lesions. Long-term prospective randomized controlled trials on a larger population are necessary to determine the extent and duration of the benefits observed

The median nerve compression in the carpal tunnel is the most common compression syndrome of the upper limb. In most cases it is idiopathic but may also occur from anatomical, traumatic, endocrine, rheumatic or tumoral causes. Chow's endoscopic technique was initially used to treat this disease and then modified to a mini-open approach through a single palmar incision. This incision is similar to the one used in endoscopic release by Agee. After exposing the proximal part of the transverse carpal ligament a meniscus knife is advanced until there is a complete section of the ligament, without endoscopic equipment. Between 2004 and 2006, 200 hands in 179 patients with a diagnosis based on clinical and electromyographic criteria were operated by this mini-open technique. The mean follow-up was 49 months (minimum of 34 months and a maximum of 70 months). 50 randomly selected patients were submitted to the self-administered Boston questionnaire. 50 patients treated by the minimal-incision decompression during the same period were also given the questionnaire. The aesthetic satisfaction was registered as well as if they would have surgery on the other hand or would recommend the procedure. This mini-open technique is another technique available to the surgeon that allows very similar functional results to endoscopic surgery, without use of specific material and with a shorter surgical time

Background. The mechanical disadvantage and detrimental effect to articular cartilage following meniscectomy has been well documented in the literature. Meniscal repair in the avascular (white on white zone) is controversial and would be deemed inappropriate by many. Methods. Prospective data collection on all meniscal repairs between 1999 and 2008. 423 patients underwent meniscal repair at our unit during this time. We identified 88 patients who underwent a meniscal repair of a non peripheral tear (white on white zone) where there was no co-existent ACL injury or instability. There were 74 males and 14 females with a mean age of 26 years (13-54). There were 50 medial meniscal tears and 38 lateral tears, all in the non peripheral area of the meniscus. The criterion for failure was any reoperation on the same meniscus requiring excision or re fixation. Results. The mean follow up was 44 months (5–106). Twenty nine patients required further surgery on their repaired meniscus. There were nine re-repairs and twenty partial menisectomies. Of the nine re-repairs only one has gone on to have a further procedure with meniscectomy. This represents a success rate of 67% (59/88). The mean pre-operative Lysholm score was 61 (4-88) which rose to 75 (12-100) postoperatively, (p=0.002). The mean pre-operative Tegner score was 6 (3-10) and this did not change significantly post operatively, mean 6 (0-10) (p=0.4). Conclusions. Isolated white on white avascular meniscal tears can be successfully repaired in the majority of cases with a good clinical and functional result

Introduction. Unicompartmental arthroplasty is still a controversial issue in knee replacement, mainly due to a marked variation in published survival rates of the implants. The aim of this study was to analyse possible risk factors for revision following Oxford unicompartmental knee arthroplasties (OUKA). Material and methods. Since 1997 data for all patients with primary and revision knee arthroplasties performed in our department have been stored in a database. Selected for the present study was all primary OUKA performed in the period 1997–2006 as well as any revision following these operations until the end of 2008. We got information from The National Health Register and the CPR register about any revision performed at other institutions and date in case of death. Primary OUKA were grouped in three categories according to the experience of the surgeon: 1 for operation done by a surgeon who had performed less than 20 OUKA, 2 for operation by a surgeon who had performed 20–40, and 3 for operation by a surgeon who had performed more than 40. Risk of revision was analysed by Cox regression. Revisions due to pain as the only reason were excluded from the analyses. Age and gender of the patients, previous surgical intervention, operation time, and the experience of the surgeon were included as possible risk factors in the analysis. Results. 445 primary Oxford knee arthroplasties were included. These were followed by 46 revisions. The indications for the revisions were: aseptic loosening 16 knees, progression of the osteoarthritis to the lateral compartment 7 knees, dislocation of the polyethylene meniscus 5 knees, varus-valgus instability 3 knees, fracture of the medial tibia condyle 3 knees, collision of the polyethylene meniscus and the femur condyle 1 knee, and pain as the only reason 11 knees. Age and gender of the patients as well as previous surgical intervention in the knee in question were not correlated to the risk of revision. Operation time was correlated to risk of revision with decreasing risk with increasing operation time (p=0,001). The experience of the surgeon was also correlated to risk of revision with decreasing risk with increasing experience (p=0,02). The 6 years survival rate for an experienced surgeon using an operation time at 90 min. or more was 97,5 % compared to a survival rate at 78,7 % for an inexperienced surgeon with an operation time less than 90 min. Conclusion. OUKA performed by an inexperienced surgeon and OUKA performed with short operation time had marked reduced survival rates. This seems to be an essential information to institutions performing OUKA

INTRODUCTION. The TFCC injuries are usually diagnosed by a coronal MRI. We have described the Float image for the diagnosis of peripheral injuries of the TFCC. In a sagital image parallel to the ulnar diaphysis and placed lateral to the ulnar fovea, we can observe the radiocubital dorsal and volar ligaments of the TFCC. A distance of more than 4mm between the dorsal edge of the meniscus and the joint capsule suggests the presence of TFCC peripheral rupture. METHOD. 51 pacients were selected from all the patients who underwent wrist arthroscopy between 2006–2009. Inclusion criteria: MRI at our hospital, arthroscopy at our hospital, no presence of radial fracture. We assessed the correlation between the presence of the Float image and a TFCC injury confirmed by arthroscopy. RESULTS. The Float image for the diagnosis of peripheral TFCC injuries has a sensibility of 0.929 [0.774 to 0.98] and a specificity of 0,857 [0.654 to 0.95]. PPV: 0.897 [0.736 to 0.964] and NPV: 0.9 [0.699 to 0.972]. CONCLUSIONS. The Float MRI is a high sensibility and specificity method for the diagnosis of peripheral TFCC. The coronal MRI is useful for diagnosing central ruptures but has less sensibility for the peripheral injuries

Introduction. There has been renewed interest in the unicompartmental knee arthroplasty with reports of good long term outcomes. Advantages over a more extensive knee replacement include: preservation of bone stock, retention of both cruciate ligaments, preservation of other compartments and better knee kinematics. However, a number of authors have commented on the problem of osseous defects requiring technically difficult revision surgery. Furthermore, a number of recent national register studies have shown inferior survivorship when compared to total knee arthroplasty. The purpose of this study was to review the cases of our patients who had a revision total knee arthroplasty for failed unicompartmental knee arthroplasty. To determine the reason for failure, describe the technical difficulties during revision surgery and record the clinical outcomes of the revision arthroplasties. Methods. Between 2003 and 2009 our institute performed thirty three revisions of a unicompartmental knee arthroplasty on thirty two patients. The time to revision surgery ranged from 2 months to 159 months with a median of 19 months. Details of the operations and complications were taken form case notes. Patient assessment included range of motion, need for walking aids and the functional status of the affected knee in the form of the Oxford knee score questionnaire. Results. The reasons for failure were aseptic loosening of tibial component, persistent pain, dislocated meniscus, mal-alignment and osteoarthritis in another compartment. Of the 33 revision knee arthroplasties 18 required additional intra-operative constructs. 11 knees required a long tibial stem while 1 required a long femoral stem. 10 knees required medial wedge augmentation and bone graft was used in 6. Mean 1 year Oxford knee scores for failed unicompartmental knee replacements was 29 compared to 39 for primary total knee replacements performed at the same institute. Of the revision knee replacements 2 required further revision due to infection and loosening. Conclusion. From the evidence of our group of failed unicompartmental knee replacements, revision surgery is technically difficult and often requires intra-operative constructs. Clinical outcome of revision total knee arthroplasty following failed unicompartmental knee arthroplasty is not comparable to primary total knee arthroplasty

Introduction. An accurate and reproducible tibial tunnel placement without danger for the posterior neurovascular structures is a crucial condition for successful arthroscopic reconstruction of the posterior cruciate ligament (PCL). This step is commonly performed under fluoroscopic control. Hypothesis: Performing the tibial tunnel under exclusive arthroscopic control leads to accurate tunnel placement according to recommendations in the literature. Materials and Methods. Between February 2007 and December 2009, 108 arthroscopic single bundle PCL reconstructions in tibial tunnel technique were performed. The routine postoperative radiographs were screened according to defined quality criterions: 1. Overlap of the medial third of the fibular head by the tibial metaphysis on a-p views 2. Overlap of the dorsal femoral condyles within a range of 4 mm on lateral views 3. X-ray beam parallel to tibial plateau in both views. The radiographs of 48 patients (48 knees) were enrolled in the study. 10 patients had simultaneous ACL reconstruction and 7 had PCL revision surgery. The tibial tunnel was placed under direct arthroscopic control through a posteromedial portal using a standard tibial aming device. Key anatomical landmarks were the exposed tibial insertion of the PCL and the posterior horn of the medial meniscus. During digital analysis of the postoperative radiographes, the centre of the posterior tibial outlet was determined. On the a-p view, the horizontal distance of this point to the medial tibial spine was measured. The distance to the medial border of the tibial plateau was related to its total width. On the lateral view the vertical tunnel position was measured perpendicularly to a tangent of the medial tibial plateau. Results. The mean mediolateral tunnel position was 49,3 ± 4,6%, 6,7 ± 3,6 mm lateral to the medial tibial spine. On the lateral view the tunnel centre was 10,1 ± 4,5 mm distal to the bony surface of the medial tibial plateau. Neurovascular damage was observed in none of our patients. Conclusion. The results of this radiological study confirm that exclusive arthroscopic control for tibial tunnel placement in PCL reconstruction yields reproducible and accurate results according to the literature. Our technique avoids radiation, facilitates the operation room setting and enables the surgeon to visualize the key landmarks for tibial tunnel placement

Background. Injury to the ACL is a significant problem and can cause further damage to the internal structures of the knee. ACL injury is associated with injuries to other structures in the knee such as the meniscus and chondral cartilage. Such intra articular injuries pre-dispose the knee to develop arthritis. This injury is usually seen in young and active people usually related to sporting injuries. There is a paucity of literature on the influence of anthropometric features on the hamstring graft obtained in ACL reconstruction, although there are studies on the sex based differences affecting the hamstring graft. This study was undertaken to assess the influence of anthropometric measurements on the graft thickness obtained at ACL reconstruction surgery within the UK population. Objective. This study was undertaken to assess the influence of anthropometric measurements (body mass index (BMI), height and weight) on the graft thickness obtained at anterior cruciate ligament reconstruction surgery. Materials and methods. Data from 121 consecutive patients who had undergone ACL reconstruction by the same surgeon using quadrupled hamstring grafts were analysed. The body mass index, height and weight of these patients were correlated with the graft thickness obtained during surgery. Regression analysis was undertaken to assess the influence of individual anthropometric variables on the graft thickness. Results. Of the 121 patients there were 108 males and 13 females. Average age of the cohort was 32 years (14–55). There was a statistically significant positive correlation between the height and graft size (r=0.38, p < 0.01) as well as between the body weight and graft size (r=0.29, p < 0.01). However, when body mass index was calculated, the correlation was not statistically significant (r=0.08, p > 0.1). Regression analysis confirmed that BMI was not statistically significant as a predictor of hamstring graft diameter whereas height was statistically the most important predictor (F=20.1; p < 0.01) and yielded the predictive equation from regression analysis. Graft diameter=4.5 + 0.02 × Ht. (in cms) suggesting that people with height less than 125 cms (4′1″) are at greatest risk of a quadrupled graft size of less than 7 mm. Conclusion. Our findings suggest that although body mass index did not significantly correlate, individual anthropometric variables (height and weight) do influence the size of graft thickness in ACL reconstruction and give pre operative information. This may allow surgeons to plan for alternative graft options, if they could predict the possibility of inadequate graft size prior to ACL reconstruction surgery

INTRODUCTION. Computer-aided systems have been developed recently in order to improve the precision of implantation of unicompartmental knee replacement (UKR). Minimal invasive techniques may decrease the surgical trauma related to the prosthesis implantation, but there might be a concern about the potential for a loss of accuracy. Mobile bearing prostheses have been developed to decrease the risk of polyethylene wear, but are technically more demanding. Navigation might help to compensate for these difficulties. We wanted to combine the theoretical advantages of the three different techniques by developing a navigated, minimal invasive, mobile bearing unicompartmental knee prosthesis. MATERIAL AND METHODS. 160 patients have been operated on at our institution with this system. The 81 patients with more than 2 year follow-up have been re-examined. Complications have been recorded. The clinical results have been analyzed according to the Knee Society Scoring System. The subjective results have been analyzed with the Oxford Knee Questionnaire. The accuracy of implantation has been analyzed on post-operative antero-posterior and lateral long leg X-rays. The 2-year survival rate has been calculated. RESULTS. We observed 8 complications related to the implant or the operative technique: 2 cases of meniscus instability (1 revision to TKR, 1 bearing exchange); 2 cases of tibia loosening (revised to TKR), 2 cases of femoral loosening (revised to TKR), 1 case of lateral disease progression (revised to TKR), 1 case of unexplained pain syndrome (revised to TKR). The mean Knee Score was 93 points, 44% had the maximum of 100 points, and only 10% have less than 85 points. The mean pain score was 48 points/50. The mean flexion angle was 128°, and 60% had at least 130° of knee flexion. The mean Function Score was 97 points, 84% have the maximum of 100 points, and only 5% had less than 85 points. The mean Oxford Knee Questionnaire score was 19 points (best result: 12 points, worst result: 60 points). Expected limb axis correction was obtained in 77% of the cases. 62% of the cases had an optimally implanted prosthesis for all studied criteria. The 2-year survival rate was 97%. DISCUSSION. Most of the revision cases were related to technical difficulties during the development phase. Fixation of the implant has been improved, and some imprecise steps of the software have been corrected. Since these changes occurred, no severe early complication related to implant or software has been observed. The current implant is considered reliable, and the current minimal invasive navigated technique is considered reliable as well

We retrospectively analysed the clinical results of 30 patients with injuries of the sternoclavicular joint at a minimum of 12 months’ follow-up. A closed reduction was attempted in 14 cases. It was successful in only five of ten dislocations, and failed in all four epiphyseal disruptions. A total of 25 patients underwent surgical reduction, in 18 cases in conjunction with a stabilisation procedure.

At a mean follow-up of 60 months, four patients were lost to follow-up. The functional results in the remainder were satisfactory, and 18 patients were able to resume their usual sports activity at the same level. There was no statistically significant difference between epiphyseal disruption and sternoclavicular dislocation (p > 0.05), but the functional scores (Simple Shoulder Test, Disability of Arm, Shoulder, Hand, and Constant scores) were better when an associated stabilisation procedure had been performed rather than reduction alone (p = 0.05, p = 0.04 and p = 0.07, respectively).

We recommend meticulous pre-operative clinical assessment with CT scans. In sternoclavicular dislocation managed within the first 48 hours and with no sign of mediastinal complication, a closed reduction can be attempted, although this was unsuccessful in half of our cases. A control CT scan is mandatory. In all other cases, and particularly if epiphyseal disruption is suspected, we recommend open reduction with a stabilisation procedure by costaclavicular cerclage or tenodesis. The use of a Kirschner wire should be avoided.

Coronal plane fractures of the posterior femoral condyle, also known as Hoffa fractures, are rare. Lateral fractures are three times more common than medial fractures, although the reason for this is not clear. The exact mechanism of injury is likely to be a vertical shear force on the posterior femoral condyle with varying degrees of knee flexion. These fractures are commonly associated with high-energy trauma and are a diagnostic and surgical challenge. Hoffa fractures are often associated with inter- or supracondylar distal femoral fractures and CT scans are useful in delineating the coronal shear component, which can easily be missed. There are few recommendations in the literature regarding the surgical approach and methods of fixation that may be used for this injury. Non-operative treatment has been associated with poor outcomes. The goals of treatment are anatomical reduction of the articular surface with rigid, stable fixation to allow early mobilisation in order to restore function. A surgical approach that allows access to the posterior aspect of the femoral condyle is described and the use of postero-anterior lag screws with or without an additional buttress plate for fixation of these difficult fractures.

Cite this article: Bone Joint J 2013;95-B:1165–71.

The purpose of this study was to review the long-term outcomes of a previously reported prospective series of 46 type III acromioclavicular dislocations. These were treated surgically with temporary fixation of the acromioclavicular joint with wires, repair of the acromioclavicular ligaments, and overlapped suture of the deltoid and trapezius muscles. Of the 46 patients, one had died, four could not be traced, and three declined to return for follow-up, leaving 38 patients in the study. There were 36 men and two women, with a mean age at follow-up of 57.3 years (41 to 71). The mean follow-up was 24.2 years (21 to 26).

Patients were evaluated using the Imatani and University of California, Los Angeles (UCLA) scoring systems. Their subjective status was assessed using the Disabilities of the Arm, Shoulder and Hand and Simple Shoulder Test questionnaires, and a visual analogue scale for patient satisfaction. The examination included radiographs of the shoulder.

At a follow-up of 21 years, the results were satisfactory in 35 (92.1%) patients and unsatisfactory in three (7.9%). In total, 35 patients (92.1%) reported no pain, one slight pain, and two moderate pain. All except two patients had a full range of shoulder movement compared with the opposite side. Unsatisfactory results were the result of early redisplacement in two patients, and osteoarthritis without redisplacement in one. According to the Imatani and UCLA scores, there was no difference between the operated shoulder and the opposite shoulder (p > 0.05). Given the same situation, 35 (92.1%) patients would opt for the same surgical treatment again.

Operative treatment of type III acromioclavicular joint injuries produces satisfactory long-term results.