Time-Dependent Clinical Results of Rotating-Platform Total Knee Arthroplasty According to Mechanical Axis Deviation

PURPOSE: We hypothesized that the low contact stress (LCS) posterior stabilization system in knees with 3degrees deviation). The clinical assessments were performed using the Knee Society score and Hospital for Special Surgery systems and Western Ontario and McMaster Universities index. RESULTS: The survival rate was 97.4% in Group 1 and 96.8% in Group 2. No statistically significant intergroup difference was observed in the clinical scores before surgery and since 1 year after surgery (p>0.05). However, a significant intergroup difference was noted between 6 months to 1 year after surgery (p<0.001). Less than 2 mm radiolucent lines were found more frequently in Group 2. Time-dependent improvement was noted within one year after TKA in both groups. CONCLUSIONS: Most of the expected improvements were achieved at 6 months after surgery in Group 1 and at 1 year after surgery in Group 2. The present study suggests that the LCS system yields time-dependent improvement regardless of coronal alignment deviation.

Posterior Cruciate Ligament: Focus on Conflicting Issues

There is little consensus on how to optimally reconstruct the posterior cruciate ligament (PCL) and the natural history of injured PCL is also unclear. The graft material (autograft vs. allograft), the type of tibial fixation (tibial inlay vs. transtibial tunnel), the femoral tunnel position within the femoral footprint (isometric, central, or eccentric), and the number of bundles in the reconstruction (1 bundle vs. 2 bundles) are among the many decisions that a surgeon must make in a PCL reconstruction. In addition, there is a paucity of information on rehabilitation after reconstruction of the PCL and posterolateral structures. This article focused on the conflicting issues regarding the PCL, and the scientific rationales behind some critical points are discussed.

Remnant Preservation is Helpful to Obtain Good Clinical Results in Posterior Cruciate Ligament Reconstruction: Comparison of Clinical Results of Three Techniques

BACKGROUND: The purpose of the present study was to compare the clinical results of 3 posterior cruciate ligament reconstruction techniques according to the time from injury to surgery and remnant PCL status and to evaluate the efficiency of each technique. METHODS: The records of 89 patients who underwent primary PCL reconstructions with a posterolateral corner sling were analyzed retrospectively. Thirty-four patients were treated by anterolateral bundle (ALB) reconstruction with preservation of the remnant PCL using a transtibial tunnel technique in the acute and subacute stages of injury (group 1). Forty patients were treated with remnant PCL tensioning and an ALB reconstruction using the modified inlay technique in the chronic stage (group 2), and fifteen patients were treated with double-bundle reconstruction using the modified inlay technique (group 3). The double-bundle reconstruction was performed if there was a very weak or no PCL remnant. RESULTS: The mean side-to-side differences in posterior tibial translation on the stress radiographs were reduced from 10.1 +/- 2.5 mm in group 1, 10.6 +/- 2.4 mm in group 2, and 12.8 +/- 3.2 mm in group 3 preoperatively to 2.3 +/- 1.4 mm in group 1, 2.3 +/- 1.5 mm in group 2, and 4.0 +/- 2.5 mm in group 3 at the last follow-up (p < 0.001, p < 0.001, and p < 0.001, respectively). Statistical analyses revealed that group 1 and group 2 were similar in terms of side-to-side difference changes in posterior tibial translation on the stress radiographs; however, group 3 was inferior to group 1 and group 2 at the last follow-up (p = 0.022). The clinical results were not significantly different among the three groups. CONCLUSIONS: Excellent posterior stability and good clinical results were achieved with ALB reconstruction preserving the injured remnant PCL in the acute and subacute stages and remnant PCL tensioning with ALB reconstruction in the chronic stage. The PCL injuries could be surgically corrected with different techniques depending on both the remnant PCL status and the interval between the knee trauma and operation.

Comparison of the Clinical Outcomes after Total Knee Arthroplasty with the LCS Rotating Platform Mobile Bearing Knee System and the PFC Sigma RP-F Mobile Bearing Knee System

BACKGROUND: We compared clinical outcomes after total knee arthroplasty with the Low Contact Stress (LCS) rotating platform mobile bearing knee system and the Press Fit Condylar Sigma rotating platform high flexion (PFC Sigma RP-F) mobile bearing knee system. METHODS: Fifty cases of total knee arthroplasty were performed with the PFC Sigma RP-F mobile bearing knee system and sixty-one cases were performed with the LCS mobile bearing total knee arthroplasty. The average duration of follow-up was 2.9 years. RESULTS: The mean Hospital for Special Surgery (HSS) knee score was 62.1 (range, 52 to 75) in the LCS group and 61.9 (range, 50 to 74) in the Sigma RP-F group preoperatively, and 90.1 (range, 84 to 100) in the LCS group and 89.8 (range, 83 to 100) in the Sigma RP-F group at the final follow-up. The mean preoperative flexion contracture was 6.7degrees (range, 0degrees to 10degrees) in the LCS group and 9.3degrees (range, 0degrees to 15degrees) in the Sigma RP-F group preoperatively. The mean range of motion was 124.6degrees (range, 105degrees to 150degrees) in the LCS group and 126.1degrees (range, 104degrees to 145degrees) in the Sigma RP-F group at the final follow-up. CONCLUSIONS: After a minimum duration of follow-up of two years, we found no significant differences between the two groups with regard to the range of knee motion or the clinical or radiographic results.

Recent Evolution of Cruciate Ligament Surgery of the Knee

No abstract available.

Cementless Total Hip Arthroplasty Using a Modular Femoral Component in Patients with Femoral Head Osteonecrosis: Comparison of Metal-on-Metal and Ceramic-on-Ceramic Articulation

PURPOSE: The purpose of this study was to evaluate the clinical and radiological outcomes after total hip arthroplasty using the S-ROM modular system for osteonecrosis of the femoral head, and to compare the results between the groups using metal-on-metal articulation and ceramic-on-ceramic articulation. MATERIALS AND METHODS: Sixty-six patients (78 hips) with osteonecrosis of the femoral head were evaluated after primary total hip arthroplasty between January 2001 and December 2004, using an S-ROM proximal modular femoral stem. The average follow-up was 77 months (range, 60 to 122 months) and all patients were followed for more than five years. RESULTS: The average Harris hip score improved from 53 points to 88.5 points at the final follow-up. At the latest radiologic evaluation, sixty-seven stems had bony ingrowth stability, and 10 stems had stable fibrous ingrowth. However, one stem had diffuse extensive osteolysis and loosening, which was revised at 9 years. Postoperative complications included 4 cases of heterotrophic ossificiation, 1 case of linear fracture after insertion of the femoral stem, 1 case of dislocation, 2 cases of infection, and 1 case of extensive osteolysis and loosening. There were 3 cases of revision and Kaplan-Meier survivorship analysis with revision estimated at a 95.7% chance of survival for the femoral component during 122 months. CONCLUSION: Our study showed that total hip arthroplasty using the S-ROM modular system with metal-on-metal articulation or ceramic-on-ceramic articulation had favorable clinical and radiological mid- to long-term results.

The Influence of Tibial Positioning on the Diagnostic Accuracy of Combined Posterior Cruciate Ligament and Posterolateral Rotatory Instability of the Knee

BACKGROUND: To determine if tibial positioning affects the external rotation of the tibia in a dial test for posterolateral rotatory instability combined with posterior cruciate ligament (PCL) injuries. METHODS: Between April 2007 and October 2007, 16 patients with a PCL tear and posterolateral rotatory instability were diagnosed using a dial test. The thigh-foot angle was measured at both 30degrees and 90degrees of knee flexion with an external rotation stress applied to the tibia in 2 different positions (reduction and posterior subluxation). The measurements were performed twice by 2 orthopedic surgeons. RESULTS: In posterior subluxation, the mean side-to-side difference in the thigh-foot angle was 11.56 +/- 3.01degrees at 30degrees of knee flexion and 11.88 +/- 4.03degrees at 90degrees of knee flexion. In the sequential dial test performed with the tibia reduced, the mean side-to-side difference was 15.94 +/- 4.17degrees (p < 0.05) at 30degrees of knee flexion and 16.88 +/- 4.42degrees (p = 0.001) at 90degrees of knee flexion. The mean tibial external rotation was 5.31 +/- 2.86degrees and 6.87 +/- 3.59degrees higher in the reduced position than in the posterior subluxation at both 30degrees and 90degrees of knee flexion. CONCLUSIONS: In the dial test, reducing the tibia with an anterior force increases the ability of an examiner to detect posterolateral rotary instability of the knee combined with PCL injuries.

Comparative Study of ACL Double-bundle Reconstruction with and without Functional Knee Brace: Minimum 1-year Follow-up Results / 대한정형외과학회잡지

PURPOSE: To compare the clinical efficacy after an arthroscopic ACL double-bundle reconstruction with and without functional knee brace. MATERIALS AND METHODS: Between July 2004 and May 2006, fifty patients who underwent an ACL double-bundle reconstruction with and without a functional knee brace for more than a 1-year follow-up were evaluated. The patients were treated with brace (Group 1, 22 cases) or without (Group 2, 28 cases) a brace after surgrey. Stability was assessed by maximal manual testing with a KT-1000 arthrometer, anterior stress radiographs using the Telos device and a lateral pivot shift test. The clinical results were assessed by the OAK (Orthopadische Arbeitsgruppe Knie) score, IKDC (International Knee Documentation Committee) score, mid thigh circumference and the range of motion. RESULTS: More than one year after surgery, average of OAK score, IKDC score, lateral pivot shift test of the stability results and maximal manual testing with the KT-1000 arthrometer, stress radiographs with the Telos device, mid thigh circumference difference, range of motion of the clinical results were similar in both groups. CONCLUSION: An ACL double-bundle reconstruction produces similar stability and clinical results regardlness of whether or not a functional knee brace is used.

Matrix Metalloproteinase-1 and Transforming Growth Factor-beta1 Expression during Distraction Osteogenesis and Fracture Healing of the Rat / 대한정형외과학회잡지

PURPOSE: To evaluate the temporal and spatial expression of Transforming Growth Factor-beta1 and Matrix Metalloproteinase-1 in distraction osteogenesis and fracture healing models. MATERIALS AND METHODS: Distraction osteogenesis was performed on the tibial diaphyses of Sprague- Dawley rats (latent period for 1 week, distraction for 2 weeks). The rats were euthanized at each week and the level of mRNA expression was assessed by real-time RT PCR and immunohistochemical staining. RESULTS: Although the level of TGF-beta1 mRNA and MMP-1 mRNA expression was increased during distraction osteogenesis and fracture healing, the level of mRNA expression was significantly higher in the distraction phase in the distraction group than in the fracture healing group at the same phase. After the distraction phase, the level of mRNA expression in both groups decreased to the base line. The peak expression of mRNA was followed by that of TGF-beta1 mRNA. Immunohistochemical staining revealed that TGF-beta1 was expressed mainly in the osteoblast and endothelial cells, and MMP-1 was expressed mainly in the endothelial cells of the vessel. CONCLUSION: There is specific time sequence in the expression of TGF-beta1 and MMP-1 during fracture healing and distraction osteogenesis. These results suggest that TGF-beta1 expression might be associated with the angiogenesis induced by MMP-1 expression during new bone formation.

A Comparison of Patella Retention versus Resurfacing in Total Knee Arthroplasty: A Minimum 7 Year Follow-up / 대한정형외과학회잡지

PURPOSE: To evaluate and report the clinical and radiological results of patients that had undergone patellar retention and resurfacing during total knee arthroplasty. MATERIALS AND METHODS: From July 1993 to December 1999, 54 patients (73 cases) underwent total knee arthroplasty by one surgeon. We divided these patients into the patellar retention group and patellar resurfacing group, and compared the clinical and radiological results of the two groups. The indications of patellar retention were a small patella, nearly normal articular cartilage, minimal preoperative patellofemoral pain, poor patellar bone quality, and young patient age. In these cases, osteophytes of the patella were removed and marginal electrocauterization was performed. There were 32 patients (41 cases) in the patellar retention group and 22 patients (32 cases) in the patellar resurfacing group. The mean follow-up period was 106.7 months in the patellar retention group and 93.6 months in the patellar resurfacing group. We evaluated the patients using the knee rating system of the American Knee Society (knee score and functional score), knee arthroplasty rating system of the Hospital for Special Surgery (HSS score), patellofemoral score, range of motion of the knee joint, and performed a radiological evaluation by use of the radiographical evaluation system of the Knee Society at the last follow-up period. Also, to evaluate patellofemoral congruence, we used Keblish's method. RESULTS: At the last follow-up, the mean knee score and functional score were 90.4 and 75.5 for the patellar retention group, and 86.1 and 70.0 for the patellar resurfacing group, respectively (p=0.29, p=0.27). The HSS score was 85.2 for the patellar retention group and 84.8 for the patellar resurfacing group (p=0.30). The Bristol patellar score and Lonner Patellofemoral score were 8.7 and 82.0 for the patellar retention group and 8.8 and 85.6 for the patellar resurfacing group, repectively (p=0.86, p=0.86). The mean value of the patellofemoral score was slightly higher in the patellar resurfacing group, but statistically there was no difference between the two groups. There were also no statistically differences in the others parameters. CONCLUSION: We obtained favorable results by selective patellar resurfacing total knee arthroplasty, although there were no significant differences for both the patellar retention and resurfacing group. We believe that it may be better to select a proper indication than to just follow the preference of the surgeon for patellar resurfacing.

Heterotopic Bone Formation in Patient who Underwent a Posterior Cruciate Ligament Reconstruction using the Inlay Method and Posterolateral Corner Sling with a Tibia Tunnel: A Case Report / 대한정형외과학회잡지

We describe a case of posterolateral capsular heterotopic ossification requiring a surgical excision after a PCL (Posterior Cruciate Ligament) reconstruction using the modified inlay method and PLCS (posterolateral corner sling) with a tibia tunnel. A 21-year-old female patient had suffered a blunt proximal tibial direct trauma 6 months earlier. She did not experience limb ischemia or a pulse deficit before she visited our out patient clinic. She had not suffered any trauma in other sites, and showed a range of motion of 0 to 30degrees at 4 months after surgery. There was no specific finding on the X-ray images. Arthroscopic adhesiolysis was performed and her range of motion increased to 0 to 120degrees. However, 6 months after the initial operation, she showed ankylosis and heterotopic ossification at the posterior aspect, which was surgically removed at 12 months postoperatively. After the second surgery, there was no recurrence and she showed a 0 to 140degrees range of motion at postoperative 42 months.

Neurolymphomatosis Involving Sciatic Nerve: A Case Report / 대한정형외과학회잡지

The term "Neurolymphomatosis" includes the infiltration of the peripheral nervous system by lymphoma and nontumor lymphocytes. A neurolymphomatosis has not been classified as a distinct entity. Hence, its characteristic symptoms are often missed, and oncologists or neurological consultants fail to obtain an accurate diagnoses. We encountered a case of non-Hodgkins lymphoma involving the sciatic nerve, which has never been reported in the orthopedic literature in Korea. We report a case of neurolymphomatosis with a brief review of the literature.

Tensioning of Lax Anterior Cruciate Ligament and Augmentation with Double Hamstring Tendon : A Report of Surgical Technique / 대한정형외과학회잡지

PURPOSE: To introduce a new surgical technique for tensioning a lax ruptured anterior cruciate ligament (ACL) with good continuity and augmenting it using the double hamstring tendon. MATERIALS AND METHODS: The clinical results were obtained from 5 cases that had been followed up for more than 1 year. Most were sports injuries but one case was the result of a traffic accident. The parameters used for examining the clinical results were the Lachman test, a pivot shift test, KT-1000 arthrometer, pull stress view, IKDC and OAK score before surgery and at the last follow-up. Three cases were checked preoperatively by MRI. Three cases who had an associated posterolateral rotatory instability underwent a reconstruction using a posterolateral corner sling through the fibular head. RESULTS: The Lachman test and pivot shift test, which were positive preoperatively, were converted to negative in all patients at the last follow-up. Two cases were C grade and two cases were D grade. These patients were converted to A grade, but one C grade case was converted to B grade in the IKDC score. In the OAK score, the average score was 68.5 (57 to 90) before surgery, and 91.2 (79 to 98) after surgery. In the KT-1000 arthrometer and pull stress view, the mean side-to-side difference was 5.6 (5 to 6) mm and 7 (5 to 8) mm before surgery and 1.5 (1 to 3) mm, 0.3 (0 to 1) mm, after surgery, respectively, except for one case who showed laxity of the contralateral side. CONCLUSION: Tensioning of a lax ACL and hamstring tendon augmentation is an effective method for correcting a lax ACL to restore joint stability and preserve the remnant proprioception.

A Comparison of Fibular Head Tunnel and Tibial Tunnel in the Reconstruction of a Posterolateral Instability of the Knee / 대한정형외과학회잡지

PURPOSE: This study compared the surgical results of various posterolateral corner sling methods performed through either the fibula head tunnel or tibia tunnel in patients with chronic PLRI (PosteroLateral Rotatory Instability). MATERIALS AND METHODS: Between January 1999 and October 2003, 20 and 19 patients who had undergone surgery for PCL (posterior cruciate ligament) tensioning and an ALB (anterolateral bundle) reconstruction through the fibula head tunnel or tibia tunnel, respectively and were followed up more than 1 year were enrolled in this study. RESULTS: The fibular head tunnel was found to be superior compared with the tibia tunnel method in terms of the operation time (36.5+/-7.5 versus 68.4+/-12.8) (p<0.0001), rotational stability (p= 0.0018) and IKDC objective score (p<0.0001). In the fibula head tunnel group, 85% of patients had an equal to normal or tighter than normal rotational stability in the tibial tunnel group with 63% having an equal to normal or tighter than normal side at the last evaluation. In the IKDC objective score, 85% of patients in the fibula head tunnel group had a rating B or higher at the last evaluation compared with 79% in the tibial tunnel group (p<0.0001). However there were no significant differences in anteroposterior stability and OAK score. CONCLUSION: The modified posterolateral corner sling through the fibula head tunnel produces better results in terms of a posterolateral rotational stability of grade II chronic PLRL in a combined PCL injury than that using the tibia tunnel method.

Tensioning of Remnant Posterior Cruciate Ligament with a Reconstruction of the Anterolateral Bundle in Chronic PCL Injuries / 대한정형외과학회잡지

PURPOSE: This report introduces a new method for tensioning the remnant PCL with a reconstruction of the anterolateral (AL) bundle of the PCL using a modified tibial inlay technique with an assessment of the outcome of this method in chronic PCL injury. MATERIALS AND METHODS: From January 1998 to August 2003, eighty six patients was underwent tensioning of a laxed remnant PCL with a reconstruction of the anterolateral bundle of the PCL. Of these, fifty two patients who were followed up for more than 2 years were evaluated. Tensioning was performed using a distal transfer of the tibial attachment with the posteromedial approach in the supine position. The AL bundle of the PCL was reconstructed with 4 bundles of a hamstring autograft or tibialis anterior tendon allograft. The stability was assessed objectively using stress radiographs with the Telos(R) device and the maximal manual test with the KT-1000 arthrometer. The clinical results were assessed by the IKDC (International Knee Documentation Committee) and OAK (Orthopadische Arbeitsgruppe Knie) scores. The posterior drawer test, varus stress test, posterolateral drawer test and dial test in 30 degrees and 90 degrees flexion were performed for a physical examination. RESULTS: The average side to side difference of the posterior tibial translation in stress radiographs with the Telos(R) device decreased from 10.4+/-2.0 mm to 2.2+/-1.0 mm. The average side to side difference in the maximal manual test with the KT-1000 arthrometer also decreased from 8.2+/-1.5 mm to 1.9+/-1.0 mm. The final IKDC score was A in eleven (21.2%), B in thirty-five (67.3%) and C in six (11.5%) patients. The average OAK score improved from 64.3+/-8.9 to 90.8+/-7.2. CONCLUSION: Tensioning of the laxed remnant PCL with a reconstruction of the AL bundle in chronic PCL injuries showed good clinical results and excellent posterior stability.

Effects of a Posterior Cruciate Ligament Resection on the Flexion-Extension Gap in Total Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: To assess the effects of a posterior cruciate ligament resection on the tibiofemoral joint gap in total knee arthroplasty. MATERIALS AND METHODS: The effect of a PCL resection on the tibiofemoral joint gap was analyzed prospectively in 58 patients (69 knees) who had undergone TKA between May 2003 and April 2006. The knee was exposed using a modified subvastus approach. The medial soft tissue was released and a tibial cutting was made first. The tibial insertion of a PCL was protected during the tibial resection by inserting a thin osteotome in front of the posterior spine. An extension and flexion gap were measured using a balancer/tensor device (Stryker Howmedica Osteonics(R), Allendale, NJ, USA) under manual maximal stress before and after the PCL resection. The change of the joint line and the posterior inclination on preoperative and postoperative lateral roentgenograms was also assessed. RESULTS: After the PCL resection, the flexion gap and extension gap increased by an average of 3.6+/-1.5 mm and 2.0+/-1.0 mm, respectively. Although the PCL resection resulted in an increasing a flexion gap and extension gap, the increase in the flexion gap was larger than that of the extension gap by 1.6 mm. CONCLUSION: A PCL resection resulted in an increase in the flexion and extension gaps by 3.6 mm and 2.0 mm, respectively. Therefore, a PCL resection would be a good alternative method for controlling the flexion-extension gap in TKA.

Management of Concomitant Posterolateral Rotatory Instability and Anterior Cruciate Ligament Injuries of the Knee / 대한정형외과학회잡지

PURPOSE: Many failures of anterior cruciate ligament (ACL) reconstruction are due to a failure to treat concomitant posterolateral rotatory instability (PLRI). We report the results of reconstruction in cases of combined PLRI and ACL injury. MATERIALS AND METHODS: From January 1998 to December 2002, 24 patients were followed-up for a mean of 25 months (range, 12 to 58), postoperatively. PLRI was treated using a biceps tenodesis or posterolateral corner sling (PLCS), through a proximal tibial or fibular head obliquely anteroinferiorly to posterosuperiorly. ACLs were reconstructed using autogenous hamstring 4 bundles with RIGIDfix(TM) on the femoral side and Intrafix(TM) with additional staple fixation on the tibial side. Clinical results were evaluated using the Orthopadishe Arbeitsgruppe Knie (OAK) and International Knee Documentation Committee (IKDC) knee scoring system. Stability was measured on pull varus stress radiographs using a Telos stress device and by using the manual maximum displacement test using a KT-1000(TM) arthrometer with 30 degrees of knee flexion. RESULTS: The mean side-to-side difference in anterior displacement measured on the pull stress radiographs was reduced from a preoperative 7.9+/-3.4 to 2.1+/-0.8 mm at the last follow-up, from 2.1+/-0.8 to 0.4+/-0.7mm on varus stress radiographs, and from 6.5+/-1.3 mm to 2.3+/-1.3 mm as measured using the KT-1000 arthrometer. The average OAK score improved from 64.1+/-11.9 to 84.4+/-9.2 points over the same period. At the final evaluation, 22 of the 24 patients (92%) had a satisfactory result according to the IKDC system. CONCLUSION: Based on our experience, we recommend arthroscopically assisted ACL reconstruction and the correction of concomitant PLRI in cases of combined ACL and posterolateral rotatory instability.

A Comparison of Modified Subvastus and Medial Parapatellar Approach in Total Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: This study evaluated the difference between the modified subvastus approach in total knee arthroplasty (TKA) and the medial parapatellar approach in terms of the postoperative function of the knees. MATERIALS AND METHODS: From March to December 2002, 40 primary TKAs from 26 patients were divided into two groups by a prospective, randomized, blinded trial. The patients were followed up for more than 1 year. The modified subvastus approach was used in 21 knees, and the medial parapatellar approach was used in the remaining 19 knees. The time of postoperatively active straight-leg raise (SLR), and the range of flexion of the operated knee were assessed at postoperative 10 days, 6 weeks, 3, 6, and 12 months. The degree of the patellar tilt and subluxation was investigated at postoperative 12 months. The data collected was analyzed using a t-test. RESULTS: The patients with the modified subvastus approach performed active straight-leg raise sooner mean, 0.5 day) than the patients operated on using medial parapatellar approach (mean 2.2 days). Knee flexion was better at post-operative 10 days in the modified subvastus approach group than the medial parapatellar approach group. However, there was no statistical difference after 6 weeks, 3 months, 6 months, and 12 months after surgery. The level of patellar tilt and subluxation was similar in the two groups. CONCLUSION: The modified subvastus approach provided the advantage of early postoperative rehabilitation in terms of an earlier active SLR and greater knee flexion at 10 days compared with the medial parapatellar approach. The use of the modified subvastus approach in primary TKA is recommended.

Principles of Unicompartmental Knee Arthroplasty / 대한정형외과학회잡지

Unicompartmental knee arthroplasty has been controversial since its introduction in the early 1970s. Refinements were made in patient selection, surgical technique, and prosthetic design. Ten-year follow up studies were reported that showed survivorship was slightly less than that reported for total knee arthroplasty but acceptable considering the theoretically conservative nature of unicompartmental surgery. Unicondylar knee arthroplasty can be an attractive alternative to osteotomy or total knee arthroplasty especially some middle-aged women. Approximately all studies with followups of 10 years or greater show that unicompartmental knee arthroplasty will have inferior survivorship to total knee arthroplasty whether from loosening, prosthetic wear, or secondary degeneration of the opposite compartment in the second decade. Recently there has been a resurgence of interest in doing unicompartmental knee arthroplasty, which was encouraged by easier recuperation, decreased hospital stays, and good functional results. Before doing a unicompartmental arthroplasty, the surgeon should answer four important questions: Is the disease truly unicompartmental? Can this be determined on a clinical examination and standard radiographs, or are more sophisticated studies such as a bone scan or an arthroscopy required? Second, if the patient does have unicompartmental disease are there any specific contraindications to the surgery? What are the limits of fixed deformity in varus or flexion that can be corrected by a unicompartmental replacement? Overcorrection of angular deformities has in the past led to increased wear of the opposite compartment. Therefore, how much should the knee be corrected? What is the minimal polyethylene thickness that is permissible?

Results of a Mobile Bearing Total Knee Replacement: Comparison of Retention and Sacrifice of the Posterior Cruciate Ligament

PURPOSE: The purpose of this study was to compare the results of posterior cruciate ligament retention and sacrificed total knee arthroplasties with mobile bearing design. MATERIALS AND METHODS: Between January 1992 and October 1997, the study consisted of two types of low contact stress(LCS) implants: a meniscal bearing implant(Group I) that retained the posterior crucaiate ligament(n=31), and a rotating platform implant(Group II) requiring sacrifice of this ligament(n=25). All patients were evaluated with pre-and postoperative range of motion and HSS(Hospital for Special Surgery)knee rating system and radiographic analysis at least five years following the knee replacement. RESULTS: The average active range of knee motion was 4 degrees-113 degrees (Group I), 5 degrees-109 degrees (Group II) preoperatively and 0 degrees-127 degrees (Group I), 0 degrees-118 degrees (Group II) at the final follow-up evaluation. The average HSS score was 61.7(Group I), 56.0(Group II) preoperatively and 90.1(Group I), 88.2(Group II) at the final follow-up evaluation. In group I, one patellar revision for patellar polyethylene breakage and one meniscal bearing change for medial meniscal bearing wear had been performed. In group II, one revision for infection and one rotating platform change had been performed for posterior instability during flexion. we had no dislocation of mobile bearing prosthesis, but 2 cases was required reoperation because of one traumatic periprosthetic fracture(Group 1) and one post. instability(Group 2). There was no significant progressive periprosthetic osteolysis on last follow-up radiographs in both groups. CONCLUSION: After five to ten years of follow-up, we found no signigicant difference between group I and II. However, it might be that subjective symptom is excellent in group I and surgical technique remains an important element of success with mobile bearing implants regardless of posterior cruciate ligament.