Posterior instability near extension is related to clinical disability in isolated posterior cruciate ligament deficient patients

The purpose of this study is to evaluate the relationship between the magnitude of knee laxity and posterior instability at different knee flexion angles and clinical disability in isolated posterior cruciate ligament (PCL) deficient patients. Knee laxity at 20° and 70° of knee flexion were evaluated using KT-2000 arthrometer, and the posterior instability at 20°, 45° and 90° of flexion were evaluated using stress radiography. We assessed the differences in the knee laxity and the tibial translation between isolated PCL deficient knees and normal knees, and between the patients with giving-way during activities of daily living (ADL) and without giving-way. There were statistical differences in the knee laxity and the tibial translation at all knee flexion angles between the PCL deficient knees and normal knees. The magnitude of the knee laxity at 20° of flexion measured with KT-2000 arthrometer was significantly larger in the patients with giving-way than those in the patients without giving-way although there was no significant difference in the tibial translation at 70° between the two groups. The tibial translation in both medial and lateral compartments at 20° and 45° measured with stress radiography were significantly larger in the patients with giving-way than those in the patients without giving-way although there was not significant difference at 90° between the two groups. These results suggested that the magnitude of the knee laxity and the posterior tibial translation at shallow knee flexion angles would be related to giving-way during ADL in isolated PCL deficient patients.     

Effects of sectioning the posterolateral structures on knee kinematics and in situ forces in the posterior cruciate ligament

The objective of this study was to determine the effects of sectioning the posterolateral structures (PLS) on knee kinematics and in situ forces in the posterior cruciate ligament (PCL) in response to external and simulated muscle loads. Ten human cadaveric knees were tested using a robotic/universal force-moment sensor testing system. The knees were subjected to three loading conditions: (a) 134-N posterior tibial load, (b) 5-Nm external tibial torque, and (c) isolated hamstring load (40 N biceps/40 N semimembranosus). The knee kinematics and in situ forces in the PCL for the intact and PLS-deficient knee conditions were determined at full extension, 30°, 60°, 90°, and 120° of knee flexion. Under posterior tibial loading posterior tibial translation with PLS deficiency increased significantly at all flexion angles by 5.5 ± 1.5 mm to 0.8 ± 1.2 mm at full extension and 90°, respectively. The corresponding in situ forces in the PCL increased by 17–¶19 N at full extension and 30° of knee flexion. Under the external tibial torque, external tibial rotation increased significantly with PLS deficiency by 15.1 ± 1.6° at 30° of flexion to 7.7 ± 3.5° at 90°, with the in situ forces in the PCL increasing by 15–90 N. The largest increase occurred at 60° to 120° of knee flexion, representing forces two to six times of those in the intact knee. Under the simulated hamstring load, posterior tibial translation and external tibial and varus rotations also increased significantly at all knee flexion angles with PLS deficiency, but this was not so for the in situ forces in the PCL. Our data suggest that injuries to the PLS put the PCL and other soft tissue structures at increased risk of injury due to increased knee motion and the elevated in situ forces in the PCL.     

Clinical results of posterior cruciate ligament retaining TKA with alumina ceramic condylar prosthesis: comparison to Co–Cr alloy prosthesis

In a prospective study, 194 knees undergoing total knee arthroplasty (110 knees with alumina ceramic prostheses; 84 knees with Co–Cr alloy prostheses) were clinically and radiologically evaluated. Average follow-up period was 66 months (36–124 months). Average age at the time of surgery was 66 years. In the ceramic prostheses, two revision surgeries were performed because of breakage of the tibial tray and late infection, whereas two revisions of the Co–Cr alloy prostheses were carried out due to loosening and late infection. In the other patients, there were no significant differences in clinical parameters (HSS knee score and range of motion) between the two prostheses. In radiological evaluation, we could not find any radiolucent lines around the femoral ceramic component while radiolucency was present in three knees (3.6%) around the Co–Cr femoral component. Beneath the tibial tray, three knees (2.7%) showed a radiolucent line around the former prosthesis while eight knees (9.5%) demonstrated a radiolucent line around the latter prosthesis. Chi-square tests showed a significant difference in the occurrence of radiolucent line around both of the femoral and tibial prosthesis. This study demonstrated that clinical results of the alumina ceramic PCL retaining total knee prosthesis are comparable to the standard Co–Cr alloy PCL retaining total knee prosthesis. Although we could not draw any conclusions regarding the superiority of the ceramic prosthesis with respect to UHMWPE wear and long-term survivorship, this report encouraged a long-term follow-up study on ceramic prostheses. Presented in part at the meeting of the International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine, New Zealand, 2003.     

Patellofemoral kinematics during deep knee flexion after total knee replacement: a computational simulation

Purpose

Actions requiring deep knee flexion, such as kneeling and squatting, are challenging to perform after total knee replacement (TKR), though many manufactures emphasize that their knee prostheses could safely achieve high flexion. Little is known about the patellofemoral kinematics during deep flexion. This study aimed to track the movement of the patella during kneeling and squatting through dynamic computational simulation.

Methods

A validated knee model was used to analyse the patellar kinematics after TKR, including shifting, tilting and rotation. The data were captured from full extension to 135° of knee flexion. For kneeling, an anterior force of 500 N was applied perpendicularly on the tibial tubercle as the knee flexed from 90° to 135°. For squatting, a ground reaction force was applied through the tibia from full extension to 135° of flexion.

Results

This study found that patellar shifting and rotation in kneeling were similar to those while squatting. However, during kneeling, the patella had a greater medial tilt and showed signs of abrupt patellar tilt owning to an external force being concentrated on the tibial tubercle.

Conclusions

In terms of squatting and kneeling movements, the latter is a more strenuous action for the patellofemoral joint after TKR due to the high forces acting on the tibial tubercle. It is suggested that overweight patients or those requiring high flexion should try to avoid kneeling to reduce the risk of the polyethylene wear. Further modification of trochlear geometry may be required to accommodate abrupt changes in patellar tilting.

Level of evidence

II.     

Comparing in vivo kinematics of anterior cruciate-retaining and posterior cruciate-retaining total knee arthroplasty

The purpose of this study was to compare knee kinematics in patients with bi-cruciate preserving total knee arthroplasty and posterior cruciate ligament (PCL) preserving total knee arthroplasty. Five knees received PCL-retaining arthroplasty and nine knees received both cruciate-retaining arthroplasty (ACL/PCL knees). We studied treadmill gait, stair stepping, and maximum flexion activities using lateral fluoroscopy and shape matching. For maximum flexion, the ACL/PCL knees showed 6 mm more posterior translation of the lateral condyle (p < 0.05). For the stair activity, posterior translations of the lateral condyle were significantly greater in the ACL/PCL knees from 30° to 70° flexion (p < 0.05). Both condyles in the ACL/PCL knees showed greater posterior translation in the stance and swing phases of gait than in the PCL knees (p < 0.05). Preserving both cruciate ligaments in total knee arthroplasty appears to maintain some basic features of normal knee kinematics in these activities.     

Contribution of the meniscofemoral ligament as a restraint to the posterior tibial translation in a porcine knee

The meniscofemoral ligament (MFL) is a major structure in the posterior aspect of the porcine knee together with the posterior cruciate ligament (PCL). While the porcine knee is a frequently used animal model for biomechanical evaluation of PCL reconstruction techniques, the contribution of the MFL to stability of the porcine knee is not well understood. The purpose of this study is (1) to evaluate the kinematics of the knee after sequential cutting of the PCL and MFL and (2) to determine the in situ forces of the PCL and MFL in response to a posterior tibial load of 89 N using the robotic/universal force-moment sensor system from 15° to 90° of knee flexion. Ten porcine knees were used in this study. The magnitude of posterior tibial translation under a posterior tibial load was significantly increased (P < 0.01) after sequential transection of the PCL and the MFL at each testing angle compared to the intact condition. The in situ force of the PCL was highest at 60° of flexion (82.3 ± 8.6 N) and lowest at 15° of flexion (45.1 ± 15.9 N). The in situ force of the MFL was highest at 15° of flexion (24.3 ± 6.5 N) and lowest at 90° of flexion (12.9 ± 10.5 N). The findings in this study revealed a biomechanical contribution of the MFL as the secondary restraint to the posterior tibial translation in conjunction with the PCL especially near full extension.     

Dysfunction of the posterior cruciate ligament in total knee arthroplasty

Purpose  

Total knee arthroplasty (TKA) is typically carried out either with retention (CR) of the posterior cruciate ligament (PCL) or with sacrifice of this ligament and implantation of a posterior stabilised (PS) prosthesis. This paper investigates a comparison of PCL function in knees treated for osteoarthritis with TKA where the PCL is preserved to those knees treated with TKA and posterior stabilisation.     

Posterior cruciate ligament reconstruction with the quadriceps tendon in chronic injuries

We reviewed 18 patients (knees) operated on because of chronic PCL insufficiency. Preoperatively all the patients were severely disabled and showed a posterior drawer of 10 mm or more. A quadriceps tendon autograft was implanted using an open technique, direct posterior approach, and fixation to the tibia. A free semitendinosus graft was used to reconstruct the lateral collateral ligament in six knees and the medial collateral ligament in two. The patients were reviewed with a mean follow-up of 3.5 years (range 2-5.5) using the IKDC form. Stability was evaluated by stress radiography using the Telos device. The mean side-to-side difference in posterior tibial displacement at 70 degrees of knee flexion at follow-up was 4.8 mm; the side-to-side difference was less than 5 mm in 77% of cases. A side-to-side difference less than 2 mm in lateral joint line opening was found in five of six knees with a lateral collateral ligament reconstruction. Posterior tibial translation was similar in the knees with and those without collateral ligament reconstruction. Only one patient complained of significant pain and giving-way at follow-up. Patellofemoral crepitation was present in nine knees at follow-up although it was symptomatic only in one. The results of this series suggest that posterior cruciate ligament reconstruction using an autologous quadriceps tendon is a valuable option to reconstruct these severe injuries.     

Three different cruciate-sacrificing TKA designs: minor intraoperative kinematic differences and negligible clinical differences

Purpose

The goal of this study was to compare three types of mobile-bearing posterior cruciate ligament (PCL)-sacrificing TKA. The hypothesis was that the three designs provide differences in flexion stability and femoral rollback and improved clinical score at 2-year follow-up.

Methods

Three groups of patients, divided according to implant design, were analysed retrospectively. All operations were guided by a non-image-based navigation system that recorded relative femoral and tibial positions in native and implanted knees during: passive range of motion and anterior drawer test at 90° flexion. WOMAC, KSS and SF36 scores were collected pre-operatively and at 2-year follow-up.

Results

There are no differences in kinematic or clinical performance of the three implants, except for the antero-posterior translation during stress test in flexion: only Cohort B had comparable pre- and post-operative laxity test values (p < 0.001). All three TKA designs allowed to maintain pre-operative tibial rotation pattern through all range of knee flexion. All clinical scores of the three patient cohorts were significantly improved post-operatively compared to the pre-operative values (p < 0.001). Moreover, we found no differences among post-operative results of the three designs.

Conclusion

Despite design variations, mobile-bearing PCL-sacrificing TKA reproduces femoral rollback and screw-home with little or no difference in clinical or functional scores at a follow-up of 2 years.

Level of evidence

III.     

后交叉韧带止点形态学测量及其重建骨道直径探讨

目的:在膝关节尸体标本上测量后交叉韧带(PCL)止点的形态大小,探讨重建PCL时骨道直径的选择。方法:解剖20具新鲜冷冻的膝关节尸体标本,标记PCL股骨和胫骨止点边界和前外束(AL)与后内束(PM)的分界。确定PCL、AL和PM纵轴并测量其长度,经过纵轴中点做其垂线,沿垂线测量其止点宽度,该宽度则为骨道最大直径。测量值用均数(第25百分位数~第75百分位数)表示。结果:PCL、AL和PM胫骨止点的纵轴宽度分别为10.64(9.52~11.51)mm,6.54(5.50~7.58)mm和5.85(5.37~6.56)mm。股骨止点纵轴宽度分别为11.01(10.27~12.04)mm,9.56(8.91~10.52)mm和9.47(8.85~10.28)mm。结论:根据解剖重建和胫骨、股骨骨道一致的原则,PCL单束重建的骨道直径可从9.5 mm到11.5 mm,均值10.5 mm;双束重建AL骨道直径可从6.5 mm到8.5 mm,均值7.5 mm;PL骨道直径可从6.0 mm到7.5 mm,均值6.5mm。     

Partial restoration of knee kinematics in severe valgus deformity using the medial-pivot total knee arthroplasty

Purpose

The objectives of the study were to examine knee kinematics in knees with severe valgus deformities and to compare pre- and post-operative knee kinematics for the same subjects implanted with medial-pivot total knee arthroplasty (TKA).

Methods

Seven subjects with severe valgus deformities due to osteoarthritis (OA) or rheumatoid arthritis (RA) were enrolled in the prospective study. Prior to TKA, three-dimensional (3D) kinematics were assessed by 3D to 2D registration technique using the image matching software ‘Knee Motion’, under in vivo, weight-bearing conditions. Postoperatively, each subject again performed the same motion under fluoroscopic surveillance.

Results

Preoperative kinematics demonstrated external rotation of tibias from extension to flexion, and small posterior femoral translations dominated in the medial condyle associated with anterior slides during partial range of motion. Postoperatively, these non-physiological tibial rotations were restored, and most subjects exhibited small internal rotations of tibias. On average, preoperative tibial internal rotation was ?4.7° ± 7.6° from full extension to maximum flexion, and the angle was 4.8° ± 3.1° postoperatively (p = 0.01). In addition, small amounts of posterior translation of the lateral condyle and anterior translation of the medial condyle were confirmed in most subjects postoperatively.

Conclusions

The study showed that the preoperative kinematic pattern established in severe valgus deformity was different from the physiological knee pattern. In addition, post-operative results suggest that the non-physiological kinematics were partially restored after TKA by using the prosthesis design even in the absence of the posterior cruciate ligament (PCL) and the cam–post mechanism.

Level of evidence

II.     

Measurement of posterior tibial translation in the posterior cruciate ligament-reconstructed knee: significance of the shift in the reference position

BACKGROUND: The measurement of anterior or posterior tibial translation depends on the existence of a repeatable and accurate reference position of the knee from which the corresponding translation is measured. HYPOTHESIS: Clinical measurements of posterior tibial translation alone do not accurately reflect the laxity of posterior cruciate ligament-reconstructed knees. STUDY DESIGN: Controlled laboratory study. METHODS: Ten human cadaveric knees were tested by using a robotic/universal force-moment sensor testing system. The reference positions and the resulting kinematics in response to a 134-N anterior-posterior tibial load were determined for the intact and reconstructed knees. Posterior cruciate ligament reconstruction was performed with the graft tensioned and fixed at two different positions: 1) 90 degrees of knee flexion with a 134-N anterior tibial load and 2) full extension with no load. RESULTS: Posterior cruciate ligament reconstruction with graft fixation at full extension with no load resulted in anterior shift of the reference position by 1.5 to 3.2 mm. The reconstruction resulted in an overconstrained knee with significantly decreased total anterior-posterior translation of 2.6 to 3.2 mm. However, the posterior tibial translation measured was not significantly different from that of the intact knee. Posterior cruciate ligament reconstruction with graft fixation performed at 90 degrees of flexion with a 134-N anterior tibial load resulted in kinematics similar to those of the intact knee. CONCLUSION: Posterior tibial translations that are measured clinically can be misleading because the reference position of the knee can be shifted significantly after posterior cruciate ligament reconstruction. Clinical Relevance: The measurement of total anterior-posterior translation may be a more accurate way to assess kinematics of the reconstructed knee.     

The Gore-Tex prosthetic ligament as a salvage procedure in deficient knees

The purpose of this study was to evaluate the results of prosthetic ligament replacement of the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) with the Gore-Tex polytetrafluorethyene prosthesis (W.L.Gore and Co., Flagstaff, Ariz.) in 52 patients (54 knees). All patients sustained multiple (failed) knee operations or had knees with gross instability. Twenty-eight (29 knees) of the ¶52 patients (54%) in whom the Goretex prosthesis was still in situ were available at a minimum follow-up of 5 years (mean 9 years, range 5–11 years). The mean age at examination was 39 years (range 30–57 years); there were 15 men and 13 women. The results of the procedure were compared with the results of the same patients at a mean follow-up of 3 years. Eighty-one percent of the patients of the whole group complained about pain. This was 78% for the patients with an ACL reconstruction and 75% for the patients with a PCL reconstruction. The Tegner activity score and the Lysholm knee score showed a statistically significant difference over time. The anterior instability pattern improved in only 43% of the knees and the posterior instability in 41% of the knees. The Lachman test showed also a significant difference over time. In all patients X-ray showed an increase in degenerative changes. In conclusion, the PTFE prosthetic ligament in the reconstruction of the ACL and the PCL in the (chronically) unstable knee seems to deteriorate over time.     

Comparing in vivo kinematics of unicondylar and bi-unicondylar knee replacements

Preserving both cruciate ligaments in unicondylar knee arthroplasty likely provides more normal knee mechanics and contributes to enhanced patient function. It follows that preserving both cruciate ligaments with total knee arthroplasty should provide functional benefit compared to arthroplasty sacrificing one or both cruciates. The purpose of this study was to compare knee kinematics in patients with optimally functioning cruciate-preserving medial unicondylar and bi-unicondylar arthroplasty to determine if knee motions differed. Eight consenting patients with seven medial unicondylar and five bi-unicondylar arthroplasties were studied using lateral fluoroscopy during treadmill gait, stair stepping, and maximum flexion activities. Patient-specific geometric models based on CT and CAD data were used for shape matching to determine the three-dimensional knee kinematics. Tibiofemoral contact locations were computed for the replaced compartments. Maximum flexion in kneeling was 135°±14° for unicondylar knees and 123°±14° for bi-unicondylar knees (p=0.22). For 0°–30° flexion during the stair activity, the medial condyle translated posterior 3.5±2.5 mm in unicondylar knees and 4.7±1.9 mm in bi-unicondylar knees (p>0.05). Lateral posterior translation was 5.0±2.3 mm in bi-unicondylar knees for 0°–30° flexion. From heel-strike to mid-stance phase, there was little tibial rotation, but unicondylar knees showed 1.5±1.6 mm posterior translation of the medial condyle, while bi-unicondylar knees showed 5.1±2.2 mm (p<<0.05). The bi-unicondylar knees showed 3.8±3.4 mm posterior lateral condylar translation. Preserving both cruciate ligaments in knee arthroplasty appears to maintain some basic features of normal knee kinematics. Knees with bi-unicondylar arthroplasty showed kinematics closer to motions observed in total knee arthroplasty, slightly less weight-bearing flexion, and greater dynamic laxity in gait than unicondylar knees. Despite kinematic differences, knees with unicondylar and bi-unicondylar arthroplasty can provide excellent functional outcomes in appropriately selected patients.     

Total knee arthroplasty following failed high tibial osteotomy: mid-term comparison of posterior cruciate-retaining versus posterior stabilized prosthesis

This study evaluated the mid-term results of total knee arthroplasty (TKA) following high tibial osteotomy (HTO), comparing posterior cruciate-retaining prostheses to posterior stabilized prostheses. The Knee Society score for the entire group (20 knees) improved significantly from 62 (median) preoperatively to 87 at the latest follow-up. The postoperative Knee Society score of 85 in posterior cruciate-retaining prostheses (8 knees) was significantly inferior to the 94 score in posterior stabilized prostheses (12 knees). Of Knee Society score, Stability and ROM scores (17 and 21, respectively) in posterior cruciate-retaining TKA were inferior to those in posterior stabilized TKA (25 and 24, respectively). Since postoperative knee instability due to posterior cruciate ligament (PCL) insufficiency is thought to contribute to the inferior results of posterior cruciate-retaining prostheses after HTO, PCL-substituting TKA would be suitable for use after HTO.     

In vivo measurement of the pivot-shift test in the anterior cruciate ligament-deficient knee using an electromagnetic device

BACKGROUND: The pivot-shift test is commonly used for assessing dynamic instability in anterior cruciate ligament-insufficient knees, which is related to subjective knee function, unlike static load-displacement measurement. Conventional measurements of 3-dimensional position displacement cannot assess such dynamic instability in vivo and produce comparable parameters. Not only 3-dimensional position displacement but also its 3-dimensional acceleration should be measured for quantitative evaluation of the pivot-shift test. HYPOTHESIS: Knees with a positive pivot-shift test result have increased tibial anterior translation and acceleration of its subsequent posterior translation, and they are correlated with clinical grading. STUDY DESIGN: Controlled laboratory study. Materials and METHODS: Thirty patients with isolated anterior cruciate ligament injury were included. Pivot-shift tests were evaluated under anesthesia manually and experimentally using an electromagnetic knee 6 degrees of freedom measurement system. From 60 Hz of 6 degrees of freedom data, coupled tibial anterior translation was calculated, and acceleration of posterior translation was computed by secondary derivative. RESULTS: All anterior cruciate ligament-deficient knees demonstrated a positive pivot-shift test result. The coupled tibial anterior translation was 7.7 and 15.6 mm in anterior cruciate ligament-intact and -deficient knees, respectively. The acceleration of posterior translation was -797 and -2001 mm/s(2), respectively. These differences were significant (P < .01). The coupled tibial anterior translation and acceleration of posterior translation in the anterior cruciate ligament-deficient knee were larger in correlation with clinical grading (P = .03 and P < .01, respectively). CONCLUSION: The increase of tibial anterior translation and acceleration of subsequent posterior translation could be detected in knees with a positive pivot-shift result, and this increase was correlated to clinical grading. CLINICAL RELEVANCE: These measurements can be used for quantified evaluation of dynamic instability demonstrated by the pivot-shift test.     

Preservation of the posterior cruciate ligament is not helpful in highly conforming mobile-bearing total knee arthroplasty: a randomized controlled study

Purpose

The purpose of this study is to investigate whether the preservation of the posterior cruciate ligament (PCL) can be helpful for improving kinematics and clinical outcome in highly conforming mobile-bearing total knee arthroplasty (TKA).

Methods

Ninety osteoarthritic knees were randomly allocated to either the PCL-preserving group or the PCL-sacrificing group. Passive kinematics was recorded with a navigation system immediately after implantation. Three parameters (anterior/posterior translation, varus/valgus rotation, and internal/external rotation) were analysed from 0° to 120° flexion.

Results

The PCL-preserving group (42 knees) had more varus rotation over 90° flexion (p < 0.05) and more anterior translation of the femur in all ranges of flexion (p < 0.05) than those in the PCL-sacrificing group (44 knees). There was no difference in the internal/external rotation (p > 0.05). The range of motion, functional scores, and radiographic results did not significantly differ between the two groups at the final follow-up. Three knees in the PCL-preserving group were revised: two presented with instability caused by traumatic attenuation of the PCL and one with subluxation of the insert due to a tight PCL.

Conclusion

The preservation of the PCL was not helpful for improving kinematics and clinical outcome in highly conforming mobile-bearing TKA.

Level of evidence

II.     

A biomechanical comparison of posterior cruciate ligament reconstructions using single- and double-bundle tibial inlay techniques

BACKGROUND: The efficacy of using a double-bundle versus single-bundle graft for posterior cruciate ligament reconstruction has not been demonstrated. HYPOTHESIS: A double-bundle graft restores knee kinematics better than a single-bundle graft does in tibial inlay PCL reconstructions. STUDY DESIGN: Controlled laboratory study. METHODS: Eight cadaveric knees were subjected to 6 cycles from a 40-N anterior reference point to a 100-N posterior translational force at 10 degrees , 30 degrees , 60 degrees , and 90 degrees of flexion. Testing was performed for the intact and posterior cruciate deficient knee as well as for both reconstructed conditions. Achilles tendons, divided into 2 equal sections, were prepared as both single-bundle and double-bundle grafts. Both grafts were employed in the same knee, and the order of graft reconstruction was randomized. RESULTS: There were no statistical differences in translation between the intact state and either of the reconstructions (P > .05) or between either of the reconstructions at any flexion angle (P > .05). CONCLUSION: No differences in translation between the 2 graft options were identified. CLINICAL RELEVANCE: The use of a double-bundle graft may not offer any advantages over a single-bundle graft for tibial inlay posterior cruciate reconstructions.     

Mid-term clinical results of alumina medial pivot total knee arthroplasty

Purpose

The medial pivot total knee prosthesis has been designed to reproduce physiological knee kinematics. It has been reported that alumina ceramic femoral components reduce polyethylene wear. Thus, medial pivot total knee prostheses with alumina ceramic femoral components were introduced. The purpose of this study was to evaluate the clinical results of patients who underwent newly introduced alumina medial pivot total knee arthroplasties (TKA).

Methods

We evaluated the clinical results of 107 alumina medial pivot TKAs in 80 consecutive patients with a mean follow-up period of 5?years.

Results

Alumina medial pivot TKAs provided significant improvements in the patients’ Knee Society knee scores, function scores and post-operative ranges of motion compared with their pre-operative statuses (each, P?Conclusions This study demonstrates satisfactory mid-term clinical results for patients receiving the alumina medial pivot prosthesis.

Level of evidence

Therapeutic study, Level IV.     

Posterior cruciate ligament reconstruction using single-bundle patella tendon graft with tibial inlay fixation: 2- to 10-year follow-up

PURPOSE: Reconstruction of the posterior cruciate ligament (PCL) using the tibial inlay fixation has been reported as an alternative to the transtibial tunnel technique. Previous failures in PCL reconstruction and early reports raising potential biomechanical and clinical advantages have spurred interest in this technique. The purpose of this study was to evaluate the minimum 2-year results of PCL reconstruction using a single-bundle bone-patellar tendon-bone graft and tibial inlay fixation. METHODS: The authors prospectively studied 44 patients having isolated or combined PCL reconstruction using the direct tibial inlay fixation technique. The study period was from 1991 to 2001. Two-year minimum follow-up was 93% (41/44) and averaged 39.4 months. These 41 patients comprised the study group. Thirty-one patients were male and 10 patients were female; average age was 28 years. There were 35 primary and 6 revision reconstructions. Surgery was performed in the acute or subacute setting (<8 weeks) in 34% (14/41) and chronic setting in 66% (27/41). Combined reconstructions involving the posterolateral corner, anterior cruciate ligament (ACL), or medial collateral ligament (MCL) were done in 85% (35/41). In all patients, preoperative posterior drawer (PD) examination demonstrated greater than 12 mm posterior translation. All PCL reconstructions were performed with bone-patellar tendon-bone graft, which was 12 to 18 mm in width (16 autograft; 25 allograft). Wider tendon grafts were prepared from the allografts and tubularized to fit through an 11-mm tunnel. All patients were evaluated with preoperative and postoperative examination and x-rays. Final follow-up International Knee Documentation Committee (IKDC) subjective evaluation, final follow-up IKDC objective evaluation, and final follow-up Telos stress radiography were performed in all patients. RESULTS: Postoperative PD examination demonstrated the following: 0 (normal) in 9 patients, 1+ in 25 patients, 2+ in 7 patients, and none >2+, as compared to preoperative PD 3+ or greater in all patients in this report. No patient had <12 mm PD preoperatively. Mean improvement in PD was >2 grades of translation as compared to preoperative exam. Forty of forty-one demonstrated a solid endpoint on clinical PD testing. Final follow-up Telos stress radiography with 25 kg posterior load applied at 80 degrees to 90 degrees of flexion demonstrated average side-to-side difference of 4.11 mm (-2 to 10 mm). Average flexion loss was 4 degrees (0-15 degrees ). None lost extension. Preoperative IKDC objective evaluation rated all knees as severely abnormal based on instability. Final follow-up objective IKDC evaluation distribution was as follows: A, 4 knees; B, 24 knees; C, 11 knees; and D, 2 knees, as compared to all 41 D preoperatively. Average final follow-up IKDC subjective score was 75.1 (20-100). When assessing final follow-up stability with Telos stress radiography, primary cases were significantly more stable than revision cases (P <.05). There was no difference in stability when comparing allograft versus autograft, but improved IKDC scores were seen with allograft (P <.05). There was a trend for combined reconstructions to be more stable than isolated reconstructions. All patients evaluated their knee as improved or greatly improved and would repeat the procedure. CONCLUSIONS: Reconstruction of the PCL-deficient knee with severe posterior laxity is a challenging surgical problem, as combined instability patterns frequently coexist (85% in this study). When appropriate combined reconstructions or primary repair is used, PCL reconstruction with autologous or allograft bone-patellar tendon-bone graft using tibial inlay fixation was shown to be a successful technique at 2- to 10-year follow-up. Based on their initial experience with this technique and previous experience with open and arthroscopic techniques using a transtibial tunnel, the authors continue to use the tibial inlay technique as their preferred technique for isolated or combined reconstruction of the PCL.