Posterior Cruciate Ligament Resection Research Articles

Retention of the posterior cruciate ligament stabilizes the medial femoral condyle during kneeling using a tibial insert with ball-in-socket medial conformity.

Resecting the posterior cruciate ligament (PCL) increases posterior laxity and increases the flexion gap more than the extension gap in the native (i.e. healthy) knee. These two effects could lead to significant anterior displacement of the medial femoral condyle in kneeling following total knee arthroplasty even when using a tibial insert with a high degree of medial conformity. Using an insert with ball-in-socket medial conformity and a flat lateral articular surface, the primary purpose was to determine whether the medial femoral condyle remained stable with and without PCL retention during kneeling. Two groups of patients were studied, one with PCL retention (22 patients) and the other with PCL resection (25 patients), while kneeling at 90º flexion. Following 3D model-to-2D image registration, A-P displacements of both femoral condyles were determined relative to the dwell point of the medial socket. With PCL resection versus PCL retention, the medial femoral condyle was 5.1 ± 3.7mm versus 0.8 ± 2.1mm anterior of the dwell point (p < 0.0001). Patient-reported function scores were comparable (p ≥ 0.1610) despite a significantly shorter follow-up of 7.8 ± 0.9 months with PCL retention than 19.6 ± 4.9 months with PCL resection (p < 0.0001). Range of motion was 126 ± 8° versus 122 ± 6° with and without PCL retention, respectively (p = 0.057). Surgeons that use a highly conforming tibial insert design can stabilize the medial femoral condyle during kneeling by retaining the PCL. In patients with PCL resection, the 9mm high anterior lip of the insert with ball-in-socket medial conformity was insufficient to prevent significant anterior displacement of the medial femoral condyle when weight-bearing on the anterior tibia.

Effect of Posterior Cruciate Ligament Resection on Gap Balancing in Robot-assisted Total Knee Arthroplasty.

Retention or sacrifice of the posterior cruciate ligament (PCL) is one of the most controversial issues while performing total knee arthroplasty (TKA). This study aimed to evaluate the impact of PCL resection on flexion-extension gaps, femoral component rotation, and bone resection amounts during robot-assisted TKA. This prospective study included 40 patients with knee osteoarthritis who underwent robot-assisted posterior-stabilized (PS) TKA between September 2021 and February 2022. Of the patients, 75% were women (30/40) with a mean age and BMI of 72.6 years and 27.4 kg/m2, respectively. The guidance module and camera stand assembly were used to capture gaps before and after PCL resection. Measurements of femoral component rotation and bone resection amounts were made in cruciate-retaining (CR) TKA mode and PS-TKA mode. After PCL resection, the mean change in the medial and lateral compartments of flexion gaps increased by 2.0 and 0.6 mm, respectively (p < 0.001). Compared with the CR-TKA mode group, the bone resection amounts of the medial posterior condyle and the lateral posterior condyle in the PS-TKA mode group decreased by 2.0 ± 1.1 and 1.1 ± 1.1 mm, respectively, and the external rotation of the femoral prosthesis relative to the posterior condylar axis and trans-epicondylar line was reduced by 1.0° ± 1.3° and 1.2° ± 1.6°, respectively (p < 0.001). The release of the PCL did not affect the extension gap, but significantly increased the flexion gap. Moreover, the increases in the medial flexion gap were greater than those of the lateral flexion gap. After PCL resection, less external rotation of the femoral prosthesis and fewer bone cuts of the posterior femur were needed in PS-TKA.

PCL retained is safe in medial pivot TKA—a prospective randomized trial

PurposeMedial pivot (MP) designs resemble native knee kinematics and restore the “natural” kinematics of a knee after total knee arthroplasty (TKA). However, whether to preserve or resect the posterior cruciate ligament (PCL) is still under debate. We inquired whether sacrificing the PCL would improve range of motion, functional outcomes, and limb alignment compared to preserving the PCL in TKA using medial pivot implants (MP-TKA).MethodsThis prospective, double-blinded, randomized controlled trial consisted of 33 patients (66 knees) undergoing bilateral simultaneous MP-TKA. In one knee, a PCL preservation technique was performed, and in the contralateral knee, the PCL was resected. The primary outcome was postoperative range of motion (ROM). The secondary outcomes were visual analogue scale (VAS) score for knee pain at walking, Knee Injury and Osteoarthritis Outcome Score for symptoms (KOOS-S) and quality of life (KOOS-QoL), Oxford knee score (OKS), and Forgotten Joint Score (FJS), and measurement of the mechanical femoral-tibial axis (mFTA) on X-ray images. All patients were followed up for a minimum of 2 years after surgery.ResultsPatients who underwent MP-TKA with PCL preservation had a similar ROM at 2 years (125.45 ± 7.00 vs. 126.21 ± 6.73, p = 0.65) as those who underwent MP-TKAs with PCL resection. There was also no difference in VAS score (1.94 ± 0.79 vs. 2.00 ± 0.71, respectively, p = 0.51), OKS (39.97 ± 2.01 vs. 39.67 ± 2.03, respectively, p = 0.52), KOOS-S (84.41 ± 3.77 vs. 84.19 ± 3.57, respectively, p = 0.92), KOOS-QoL (82.94 ± 4.76 vs. 82.75 ± 4.70, respectively, p = 0.84), or FJS (72.66 ± 8.99 vs. 72.35 ± 8.64, respectively, p = 0.76) at the 2-year follow-up. No difference in the measurement of the mFTA was found between the two groups (180.27 ± 2.25 vs. 181.30 ± 2.13, respectively, p = 0.59).ConclusionThis study demonstrated that both medial pivot TKA with PCL preservation and PCL resection achieved excellent results. There was no difference at the 2-year follow-up in terms of postoperative ROM, patient-reported outcomes, or radiographic evaluation.Level of EvidenceTherapeutic study, Level I.

Optimizing Asymmetric Native Knee Flexion Gap Balance Promotes Superior Outcomes in Primary Total Knee Arthroplasty.

Replicating native knee kinematics remains the ultimate goal of total knee arthroplasty (TKA). Technology, such as robotics, provides robust intraoperative data; however, no evidence-based targets currently exist for improved clinical outcomes. Furthermore, some surgeons target a rectangular flexion space in TKA unlike the native knee. This study evaluated the effect of in vivo flexion gap asymmetry on patient-reported outcome measures (PROMs) in contemporary TKA. In vivo tibiofemoral joint space dimensions were measured during 129 TKAs using a calibrated tension device before and after complete posterior cruciate ligament resection. PROMs were compared based on the final dimensions and the change in flexion gap dimensions at 90° of flexion: (1) equal laxity, (2) lateral laxity, and (3) medial laxity. Groups did not differ by demographics ( P ≥ 0.347), clinical follow-up ( P = 0.134), tibiofemoral alignment ( P = 0.498), or preoperative PROMs ( P ≥ 0.093). Mean follow-up for the cohort was 1.5 years (range, 1-3). Pain with climbing stairs, pain while standing upright, and knees "always feeling normal" scores were superior for patients with equal or lateral laxity compared with medial laxity ( P ≤ 0.064). Pain with level walking, University of California Los Angeles activity level, KOOS JR, and satisfaction scores also tended to be superior for patients with equal or lateral laxity, although it lacked statistical significance ( P ≥ 0.111). Results of this study suggest that patients with either an equally tensioned rectangular flexion space or with later-flexion lateral laxity after posterior cruciate ligament resection may achieve superior PROMs. Findings support the clinical benefit of facilitating posterolateral femoral roll back in flexion, which mimics native knee kinematics and further helps define targets for advanced technology.

Modern Total Knee Arthroplasty Bearing Designs and the Role of the Posterior Cruciate Ligament.

The role of the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) surgery continues to be a source of debate among the adult reconstruction community. In native knee flexion, the PCL is comprised of an anterolateral and posteromedial bundle that work together to limit posterior tibial translation and allow adequate femoral rollback for deep flexion. In the arthritic knee, the PCL can often become dysfunctional and attenuated, which led to the development of posterior stabilized (PS) TKA bearing options. PS TKAs implement a cam-post construct to functionally replace a resected PCL. While PS designs may facilitate balancing knees with significant deformity, they are associated with complications such as postfracture, increased wear, and patellar clunk/crepitus. In recent years, newer designs have been popularized with greater degrees of congruency and incorporation of medial and lateral pivoting to better recreate native knee kinematics. The American Joint Registry has confirmed the recent predilection for ultra-congruent and cruciate-retaining TKA inserts over PS TKAs during the last decade. Studies have failed to identify an overall clinical superiority between the cruciate substituting and sacrificing designs. The literature has also failed to identify clinical consequences from PCL resection with modern, more conforming TKA designs. In this article, we review modern PCL sacrificing designs and discuss the impact of each on the kinematics after TKA. We also will delineate the role of the PCL in modern TKA in the hopes to better understand the recent surge in sacrificing but not substituting knee implants.

Effect of posterior cruciate ligament on knee pressure and gap measured by an electronic sensor during total knee arthroplasty

PurposeThe purpose of this study was to evaluate the change in posterior cruciate ligament (PCL) tension by directly measuring the pressure changes in the knee joint when the ligament was released or resected during total knee arthroplasty.MethodsWe prospectively analyzed 54 patients who underwent primary total knee arthroplasty (67 knees) from October 2019 to January 2022. An electronic pressure sensor was used to measure the pressure changes in the medial and lateral chambers on PCL retention, recession or resection.ResultsAt 0°, 45°, 90° and 120° of flexion, the total pressure in the knee joint of PCL retention was significantly higher than with PCL recession, and even higher than PCL resection. PCL recession or resection affected knee joint extension, and the medial/lateral pressure in the knee joint decreased. Pressure in the lateral compartment showed no significant change during knee flexion, whereas pressure in the medial compartment was significantly decreased, which also led to a change in the ratios of the medial and lateral pressures in the knee joint. After PCL resection, the flexion gap (90°) increased significantly more than the extension (0°) gap, while 46 cases displayed the same change in the flexion and extension gaps after PCL resection of the 67 cases.ConclusionThe PCL retained partial function after tibial recession. PCL resection affected both the flexion and extension gaps; although the average flexion gap increased more than the extension gap, the change in most cases of these two gaps was the same.

Posterior cruciate ligament resection under minimum medial collateral ligament release changes tibial internal rotation, joint center gap, and varus ligament balance on joint distraction force at flexion in total knee arthroplasty

BackgroundThe purpose of this study was to assess the effect of posterior cruciate ligament resection under minimum medial collateral ligament release on the joint center gap, varus ligament balance, and the rotational change of the femur and tibia. MethodsThis study included 75 knees with varus osteoarthritis that underwent total knee arthroplasty. After minimum medial collateral ligament releases and bone resection of the distal femur and proximal tibia, the joint center gap and varus ligament balance were measured before and after posterior cruciate ligament resection using a digital tensor with a joint distraction force of 89, 133, 178 N. The rotational changes under a distraction force of 200 N were captured using a navigation system. FindingsThe joint center gap and varus ligament balance at 90° and 120° of flexion significantly increased after posterior cruciate ligament resection with distraction forces of 89 N (90°: 0.4 mm / 0.9° and 120°: 0.5 mm / 0.8°), 133 N (90°: 0.9 mm / 1.3° and 120°: 0.9 mm / 1.1°), 178 N (90°: 1.5 mm / 1.9° and 120°: 1.5 mm / 1.5°). Tibial internal rotation significantly increased after posterior cruciate ligament resection at 90° (1.9°) and 120° (2.2°). InterpretationJoint distraction forces after posterior cruciate ligament resection increased the tibial internal rotation, joint center gap, and varus ligament balance at flexion. These findings indicate that posterior cruciate ligament resection should increase the lateral gap more than the medial gap due to tibial internal rotation at flexion. (245 words).

Arthroscopic Lysis of Adhesions for the Stiff Total Knee Arthroplasty.

Arthroscopic lysis of adhesions is a treatment option for patients with painful, stiff knees as a result of arthrofibrosis following knee arthroplasty, in whom prior manipulation under anesthesia (MUA) has failed. Typically, nonoperative treatment in these patients has also failed, including aggressive physiotherapy, stretching, dynamic splinting, and various pain-management measures or medications. Range of motion in these patients is often suboptimal, and any gains in flexibility will likely have hit a plateau over many months. The goal of performing lysis of adhesions is to increase the range of motion in patients with knee stiffness following total knee arthroplasty, as well as to reduce pain and restore physiologic function of the knee, enabling activities of daily living. This is a straightforward surgical technique that can be performed in a single stage. The preoperative range of motion is documented after induction of general anesthesia. The procedure begins with the establishment of standard medial and lateral parapatellar arthroscopic portals. A blunt trocar is introduced into the knee, and blunt, manual lysis of adhesions is performed in the suprapatellar pouch and the medial and lateral gutters with use of a sweeping motion after piercing and perforating the scarred adhesive bands or capsular tissue. Next, the arthroscope is inserted into the knee, and a diagnostic arthroscopy is performed. Bands of fibrous tissue are released and resected with use of electrocautery and a 4.0-mm arthroscopic shaver. Next, the posterior cruciate ligament (PCL) is visualized in full flexion. If PCL tightness is observed, the PCL can be released from its femoral origin until the flexion gap is increased. This portion of the procedure can include either partial or full release of the PCL, as indicated. Next, the arthroscope is removed and the ipsilateral hip is flexed to 90° for a standard MUA. Gentle force is applied to the proximal aspect of the tibia, and the knee is flexed. After completing the MUA, immediate post-intervention range of motion of the knee is documented, and the patient is provided with a continuous passive motion (CPM) machine set to the maximum flexion and extension achieved in the operating room. Nonoperative treatment of a stiff knee following total knee arthroplasty is well documented in the current literature. Range of motion has been shown to increase in patients undergoing proper pain management, aggressive physical therapy, and closed MUA in the acute postoperative setting. Additionally, more severe cases of established arthrofibrosis despite prior MUA can be treated with an open lysis of adhesions1-3. Arthroscopic lysis of adhesions with PCL release versus resection has been well described previously. This procedure has been shown to benefit patients in whom initial nonoperative treatment has failed. Additionally, this procedure is not limited to the immediate acute postoperative period like standard MUA3. To our knowledge, no technique video has been published outlining arthroscopic lysis of adhesions for a stiff knee following total knee arthroplasty. This procedure has been shown to provide an immediate and lasting improvement in the flexion and extension arc of the knee, as well as improved functional outcomes. Patients should be educated that improvements gained in the operating room must be sustained through physical therapy. In a study of 32 patients who underwent arthroscopic lysis of adhesions for moderately severe arthrofibrosis following a total knee arthroplasty, Jerosch and Aldawoudy reported a mean postoperative flexion of 119° in the operating room and 97° at the time of the latest follow-up. Eight patients with extensor lag showed improvement from 27° to 4°. Average Knee Society scores improved from 70 points preoperatively to 86 points at the time of the latest follow-up4. Their article showed that arthroscopic treatment of stiffness following total knee arthroplasty is a safe and effective form of treatment. Perform manual lysis of adhesions with a trocar prior to inserting the arthroscope in order to improve visualization and access.Utilize all portals and accessory portals interchangeably in order to improve access.Prescribe physical therapy with or without CPM machine immediately following surgery in order to maintain correction.Utilize pump inflow in order to help distend the tightened capsule.Protect the prosthetic surface from scratches during portal establishment.Loss of flexion implies scarring in the suprapatellar pouch and/or intercondylar notch, or PCL tightness.Loss of extension implies a tight posterior capsule, posterior osteophytes, or scarring of the PCL stump.A motorized shaver is the best tool for treatment of dense fibrous tissue, but be sure not to scratch metal total knee components. TKA = total knee arthroplastyROM = range of motionCT = computed tomographyMRI = magnetic resonance imagingESR = erythrocyte sedimentation rateCRP = C-reactive protein.

Effects of the posterior cruciate ligament and tibia insert thickness on tibiofemoral joint pressure in total knee arthroplasty: a cadaveric study.

BackgroundEmerging knowledge has highlighted the significant role of the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA). However, few studies have reported how the PCL affects tibiofemoral joint pressure (TFP), and differences in the effects of the PCL and the effects of tibial insert thickness on TFP remain unknown. Thus, this study used the sensor technique to analyze and compare the effects of PCL and tibial insert thickness on TFP during knee flexion.MethodsCruciate-retaining total knee arthroplasty (CR-TKA) was performed in 8 cadaveric knees. The PCL was partially released and completely resected sequentially while the tibial insert thickness was increased from 10- to 12-mm at 1-mm intervals. With the optimal tibial insert in place, the effects of PCL release and resection on medial and lateral TFP during knee flexion were analyzed. Medial tibiofemoral joint pressure (MTFP) with PCL retention and a 12-mm tibial insert was set as the baseline. The effects of PCL resection without tibial insert thickness reduction on MTFP were compared to the effects of PCL retention with a 1- or 2-mm thinning of the tibial insert on MTFP during knee flexion.ResultsPCL resection significantly reduced MTFP at 90° and 120° of knee flexion (P=0.01 and P=0.03, respectively). Partial release and complete resection of the PCL did not significantly reduce lateral tibiofemoral joint pressure (LTFP) at 10°, 30°, 60°, 90° and 120° of knee flexion (P=0.68, P=0.60, P=0.62, P=0.21 and P=0.12, respectively). At 10°, 30°, and 60° of knee flexion, a 1-mm reduction in the tibial insert had a greater effect on MTFP than did the resection of the PCL. In contrast, at 90° of knee flexion, MTFP was more affected by PCL resection than by a 2-mm reduction of the tibial insert.ConclusionsThe PCL predominantly affects MTFP at 90° and 120° of knee flexion. The impact of PCL resection on MTFP at 90° flexion was higher than the impact of a 2-mm thinning of the tibial insert.

Posterior Cruciate Ligament Resection and Varus Correction in Total Knee Arthroplasty: A Study Using Computer-Assisted Surgery.

BackgroundAlignment correction is crucial for sustaining longevity and function in total knee arthroplasty (TKA). Although the posterior cruciate ligament (PCL) is a secondary stabilizer in the coronal plane, there have been few reports on the effects of PCL resection on varus correction. The study aim was to assess the effect of PCL resection performed using computer-assisted surgery (CAS) on varus correction in TKA.MethodsFrom April 2019 through January 2021, patients with varus deformity of <20° and grossly intact PCLs were included. We used CAS to measure varus correction and gap change after PCL resection during CAS-TKA.ResultsTwenty-four female and eight male patients (40 operated knees) were included. The mean age was 68.7 ± 9.0 years, and the mean BMI was 26.5 ± 3.7 kg/m2. The mean preoperative mechanical alignment was varus 5.7° ± 2.5°. We found that 1.4° ± 0.6° of varus correction occurred after PCL resection (P < .05). The mean extension and flexion medial-side gap increases were 0.4 mm and 2.0 mm, respectively (P < .05). The mean extension and flexion lateral-side gap increases were 0.4 mm and 1.6 mm, respectively (P < .05).ConclusionPCL resection during TKA resulted in a small degree of varus correction. The flexion gap was larger when the PCL was resected. These effects were predictable, so surgeons should be aware of these findings while performing TKA.

Three-Dimensional Effects of Posterior Cruciate Ligament Resection Under Minimal Medial Collateral Ligament Release on the Tibiofemoral Joint Gap in Total Knee Arthroplasty

Three-Dimensional Effects of Posterior Cruciate Ligament Resection Under Minimal Medial Collateral Ligament Release on the Tibiofemoral Joint Gap in Total Knee Arthroplasty

Early outcomes of ultra-congruent insert in cruciate-retaining total knee arthroplasty: A prospective study

Introduction: The exponents of cruciate-retaining (CR) total knee arthroplasty (TKA) assert that the retention of posterior cruciate ligament (PCL) preserves more normal knee kinematics, femoral rollback on the tibia during flexion, greater stabilization of the prosthesis, and improved position sense as compared to PCL resection TKA. However, one has to shift to the posterior stabilized (PS) femoral component with box and accompanying cam postpolyethylene, especially in cases where PCL is too attenuated to be functional or too tight predisposing to accelerated polyethylene wear. To minimize both the cam mechanism polyethylene wear and the bone sacrifice due to the intercondylar box cut, the ultra-congruent (UC) inserts have been developed that are characterized by a high anterior wall and a deep-dished plate, promising good stability without cam mechanism. Materials and Methods: We did a prospective study to clinically evaluate the short-term results of the patients who underwent TKA using cemented posterior CR implants and UC inserts. PCL was required to be released either partially or completely in all the study patients. Thirty patients were evaluated preoperatively and postoperatively after 12 months with the new Knee Society Knee Scoring System (2011) and the findings were statistically analyzed. Results: There was a statistically significant postoperative improvement in flexion (from mean of 87.69° to 111.53°, P = 0.000), objective knee indicators (33.53 ± 8.51–70.84 ± 4.91, P = 0.000), patient satisfaction scores (7.48 ± 2.12–21.53 ± 4.26, P = 0.000), and the functional activities score (32.53 ± 5.12–69.02 ± 6.36, P = 0.000). We did not note any disadvantage of CR TKA with UC insert and no patient underwent an early revision for instability. Conclusion: Using UC insert in CR TKA is a reliable procedure that has decreased the dependence on the PS designs.

Adjusting Insert Thickness and Tibial Slope Do Not Correct Internal Tibial Rotation Loss Caused by PCL Resection: In Vitro Study of a Medial Constraint TKA Implanted with Unrestricted Calipered Kinematic Alignment.

Most medial stabilized (MS) total knee arthroplasty (TKA) implants recommend excision of the posterior cruciate ligament (PCL), which eliminates the ligament's tension effect on the tibia that drives tibial rotation and compromises passive internal tibial rotation in flexion. Whether increasing the insert thickness and reducing the posterior tibial slope corrects the loss of rotation without extension loss and undesirable anterior lift-off of the insert is unknown. In 10 fresh-frozen cadaveric knees, an MS design with a medial ball-in-socket (i.e., spherical joint) and lateral flat insert was implanted with unrestricted calipered kinematic alignment (KA) and PCL retention. Trial inserts with goniometric markings measured the internal-external orientation relative to the femoral component's medial condyle at maximum extension and 90 degrees of flexion. After PCL excision, these measurements were repeated with the same insert, a 1 mm thicker insert, and a 2- and 4-mm shim under the posterior tibial baseplate to reduce the tibial slope. Internal tibial rotation from maximum extension and 90 degrees of flexion was 15 degrees with PCL retention and 7 degrees with PCL excision (p < 0.000). With a 1 mm thicker insert, internal rotation was 8 degrees (p < 0.000), and four TKAs lost extension. With a 2 mm shim, internal rotation was 9 degrees (p = 0.001) and two TKAs lost extension. With a 4 mm shim, internal rotation was 10 degrees (p = 0.002) and five TKAs lost extension and three had anterior lift-off. The methods of inserting a 1 mm thicker insert and reducing the posterior slope did not correct the loss of internal tibial rotation after PCL excision and caused extension loss and anterior lift-off in several knees. PCL retention should be considered when using unrestricted calipered KA and implanting a medial ball-in-socket and lateral flat insert TKA design, so the progression of internal tibial rotation and coupled reduction in Q-angle throughout flexion matches the native knee, optimizing the retinacular ligaments' tension and patellofemoral tracking.

The Disproportionate Increase of the Intraoperative Flexion and Extension Gap Space after Posterior Cruciate Ligament Resection in Total Knee Arthroplasty.

Purpose: Maintaining gap balance is critical for total knee arthroplasty (TKA). This study aimed to elucidate if the extension–flexion gaps would be changed with posterior cruciate ligament (PCL) intact (PI) and PCL resection (PR) during TKA. The flexion gaps were measured using two methods, open-(Fo) and closed-chain position (Fc), based on the definition of kinetic chain position, respectively. Methods: This retrospective study enrolled a total of 33 patients who underwent posterior-stabilized (PS) TKA for symptomatic advanced osteoarthritis of knees. After bone cuts were completed, the extension–flexion gaps before and after PCL resection during TKA were measured using a calibrated tensioning device set at a 100 Nm distraction force. To further differentiate the effect of thigh weight on the 90° flexion gap, two varied methods of examination, either in closed chain (Fc) or open chain (Fo) were performed. Results: The increases in the 90° knee flexion gap after PCL resection were measured by both methods, i.e., ΔFc (PR-Fc—PI-Fc): 2.04 ± 2.06 mm, p < 0.001; and mean ΔFo (PR-Fo—PI-Fo): 1.64 ± 1.36 mm, p < 0.001. However, there were no differences between ΔFc and ΔFo before and after PCL resection. A greater amount of flexion gap was identified in open chain than in closed chain after PCL resection, and the PR-Fo and PR-Fc were 14.36 ± 3.13 and 11.40 ± 3.47 (p < 0.001), respectively. Conclusions: The resection of PCL during TKA distinctly increased the flexion gap, but not the extension gap. This disproportionate increase of the gap will cause a gap balance mismatch. The tensioning maneuver in open-chain was more effective to detect the gap differences than in closed-chain before and after PCL resection during TKA.

Primary total knee replacement using dished polyethylene with resected posterior cruciate ligament

&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;The choice between preserving, sacrificing or substituting the posterior cruciate ligament (PCL) is always a controversial topic in total knee replacement (TKR). Dished polyethylene insert with PCL resection enables correction of the commonly present fixed flexion and varus deformities. Additionally, the risk of premature wear of polyethylene is less because of the confirming articular geometry between the femoral and tibial component.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;This is a retrospective study in which we studied 120 knees in 95 consecutive patients undergoing primary TKR by the senior author at our institute. We used TKR system with dished metal backed polyethylene tibial component. PCL resection was performed in all cases. Pre-operative and post-operative functional assessment were done using knee society clinical scores and Western Ontario and McMaster universities osteoarthritis index (WOMAC). All radiographs were assessed using the knee society Roentgenographic scoring system (KSRES). Statistical analysis was performed using paired student t tests. Survivorship was determined using Kaplan-Meier survivorship curves. &lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Mean follow-up was 8 years. Range of motion increased from 75 degrees to 110 degrees. The knee society pain score increased from 30 to 94. The knee society function score increased from 35 to 75. WOMAC score increased in terms of pain, stiffness and physical function.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;We conclude that deep dish bearing is a viable option in presence of deficient PCL and provides adequate stability and functional outcome. We need a larger sample size, multicentre trial and longer follow-up to see for complication rate, revision rate and survival.&lt;/p&gt;

Posterior Cruciate Ligament Resection Does Not Consistently Increase the Flexion Space in Contemporary Total Knee Arthroplasty

IntroductionIt is accepted dogma in total knee arthroplasty (TKA) that resecting the posterior cruciate ligament (PCL) increases the flexion-space by approximately 4mm. Unfortunately, this doctrine is based on historical studies of limited size with variable technique. The aim of this study was to determine the effect of PCL-resection on in vivo tibiofemoral joint space dimensions in a cohort of modern TKAs. MethodsTibiofemoral joint space measurements were made during 129 standardized TKAs by two arthroplasty surgeons. A medial parapatellar approach, computer navigation and provisional bone cuts were performed in all cases with particular attention to preserving PCL integrity. The tibiofemoral gap was measured with a calibrated tension device at extension, 45-degrees, and 90-degrees before and after complete PCL-resection. Results51% of patients were female (66/129) with mean age and BMI of 69.5 years and 34.2 kg/m2, respectively. After PCL-resection, mean change in center joint space dimension increased 0.33mm at extension, 0.95mm at 45-degrees, and 1.71mm at 90-degrees (P < .001). The 90-degree flexion-space opened ≥4mm in only 10% of patients. Dividing the flexion-space change by femoral implant dimension to account for patient size, the flexion-space at 90-degrees significantly increased more in females compared to males (P = .020). ConclusionThe tibiofemoral joint space increased progressively from extension to mid-flexion through deep-flexion after PCL-resection, yet was substantially less than reported in historical studies. However, large variation in flexion-space opening was observed with some patients failing to increase the flexion-space whatsoever with PCL-resection. This runs counter to conventional TKA understanding and should be considered in modern surgical education. Level of EvidenceTherapeutic Level III.

Polyethylene spinout in the Attune\xae Cruciate-Retaining Rotating-Platform (CR RP) total knee arthroplasty performed with a cruciate-sacrificing and measured-resection technique

IntroductionPolyethylene (PE) spinout is a known but uncommon complication when using a mobile-bearing (MB) total knee arthroplasty (TKA) design. Sacrificing the posterior cruciate ligament (PCL) is within the manufacturer’s recommendations for the Attune® Cruciate-Retaining Rotating-Platform (CR RP) knee design.AimTo discuss the potential aetiology and prevention of spinout in the Attune® CR RP knee.MethodsWe used a retrospective radiological review from two centres reporting a higher rate of spinout in the Attune® CR RP knee using a cruciate-sacrificing and measured-resection technique when compared to a gap-balancing technique. Three hundred and thirty-two patients were evaluated over a 3-year period.ResultsThere were 8 out of 279 (2.86%) cases of spinout in our first cohort of patients using a measured-resection technique. There were 0 out of 53 cases of spinout in our second cohort of patients where a gap-balancing technique was used. One spinout was reduced closed, the other seven were initially revised to a thicker RP insert of the same design. Of these seven, three underwent a further revision TKA and one patient required a knee fusion/arthrodesis.ConclusionsThis study reports a higher incidence of PE spinout in the Attune® CR RP TKA when a measured-resection technique in combination with PCL resection is performed. We recommend a gap-balancing technique with conservative soft-tissue release if the surgeon is planning to sacrifice the PCL in the Attune® CR RP.

The Influence of Posterior Cruciate Ligament Resection on Tibiofemoral Joint Gap in Varus Osteoarthritic Knees.

Posterior cruciate ligament (PCL) resection during posterior-stabilized total knee arthroplasty (PS-TKA) has been reported to preferentially increase the tibiofemoral joint gap in flexion compared with extension. However, previous assessments of the joint gaps have been performed after bone resection and medial soft tissue release. Thus, these procedural steps may have the potential to influence soft tissue balance. In native knees, soft tissue laxity is generally greater in the lateral compartment than in the medial compartment both with the knee in extension and in flexion. Some surgeons may retain this natural soft tissue balance with less aggressive medial release during TKA. We performed this study to evaluate the impact of the PCL resection on the extension and flexion gaps in the absence of bone resection or medial soft tissue release. Tibiofemoral joint gaps for 41 patients (10 males and 31 females) in full extension and at 90 degrees of flexion both before and after the resections of both the anterior cruciate ligament (ACL) and PCL were assessed using a ligament tensioner device. The statistical analyze was performed using the Mann-Whitney U test. The results showed that medial gap in extension and flexion were 6.7 ± 1.0 and 7.3 ± 0.9 mm, and lateral gap in extension and flexion were 7.6 ± 1.1 and 8.4 ± 1.6 mm, respectively. Thus, physiological tibiofemoral gaps just after knee arthrotomy were trapezoidal and asymmetric shape with the significantly wider gaps in lateral and flexion, compared with the medial and extension, respectively (p < 0.05). However, the increases of the gaps with the ACL and PCL resections were less than 1 mm under the existence of medial soft tissues. As the medial collateral ligament is the primary restraint for the valgus instability, it was also considered to prevent the increase of the flexion gap although the PCL-which is the secondary restraint for the valgus instability-was resected. This finding is critically important for orthopedic surgeons applying PS-TKA implants, particularly for preserving soft tissues to achieve natural knee kinematics postoperatively.

Effect of surgical parameters on the biomechanical behaviour of bicondylar total knee endoprostheses \u2013 A robot-assisted test method based on a musculoskeletal model

The complicated interplay of total knee replacement (TKR) positioning and patient-specific soft tissue conditions still causes a considerable number of unsatisfactory outcomes. Therefore, we deployed a robot-assisted test method, in which a six-axis robot moved and loaded a bicondylar cruciate-retaining (CR)-TKR in a virtual lower extremity emulated by a musculoskeletal multibody model. This enabled us to systematically analyse the impact of the posterior cruciate ligament (PCL), tibial slope, and tibial component rotation on TKR function while considering the physical implant components and physiological-like conditions during dynamic motions. The PCL resection yielded a decrease of femoral rollback by 4.5 mm and a reduction of tibiofemoral contact force by 50 N. A reduced tibial slope led to an increase of tibiofemoral contact force by about 170 N and a decrease of femoral rollback up to 1.7 mm. Although a higher tibial slope reduced the contact force, excessive tibial slopes should be avoided to prevent joint instability. Contrary to an external rotation of the tibial component, an internal rotation clearly increased the contact force and lateral femoral rollback. Our data contribute to improved understanding the biomechanics of TKRs and show the capabilities of the robot-assisted test method based on a musculoskeletal multibody model as a preoperative planning tool.

Posterior cruciate ligament resection in total knee arthroplasty: the effect on flexion-extension gaps, mediolateral laxity, and fixed flexion deformity.

The aim of this study was to assess the effect of posterior cruciate ligament (PCL) resection on flexion-extension gaps, mediolateral soft-tissue laxity, fixed flexion deformity (FFD), and limb alignment during posterior-stabilized (PS) total knee arthroplasty (TKA). This prospective study included 110 patients with symptomatic osteoarthritis of the knee undergoing primary robot-assisted PS TKA. All operations were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess gaps before and after PCL resection in extension and 90° knee flexion. Measurements were made after excision of the anterior cruciate ligament and prior to bone resection. There were 54 men (49.1%) and 56 women (50.9%) with a mean age of 68 years (sd 6.2) at the time of surgery. The mean preoperative hip-knee-ankle deformity was 4.1° varus (sd 3.4). PCL resection increased the mean flexion gap significantly more than the extension gap in the medial (2.4 mm (sd 1.5) vs 1.3 mm (sd 1.0); p < 0.001) and lateral (3.3 mm (sd 1.6) vs 1.2 mm (sd 0.9); p < 0.01) compartments. The mean gap differences after PCL resection created significant mediolateral laxity in flexion (gap difference: 1.1 mm (sd 2.5); p < 0.001) but not in extension (gap difference: 0.1 mm (sd 2.1); p = 0.51). PCL resection significantly improved the mean FFD (6.3° (sd 4.4) preoperatively vs 3.1° (sd 1.5) postoperatively; p < 0.001). There was a strong positive correlation between the preoperative FFD and change in FFD following PCL resection (Pearson's correlation coefficient = 0.81; p < 0.001). PCL resection did not significantly affect limb alignment (mean change in alignment: 0.2° valgus (sd 1.2); p = 0.60). PCL resection creates flexion-extension mismatch by increasing the flexion gap more than the extension gap. The increase in the lateral flexion gap is greater than the increase in the medial flexion gap, which creates mediolateral laxity in flexion. Improvements in FFD following PCL resection are dependent on the degree of deformity before PCL resection. Cite this article: Bone Joint J 2019;101-B:1230-1237.