**10. Conclusion**

The most recent literature and National Joint registries confirm that CR-TKR has good clinical results and excellent intermediate and long-term survival.

**Figure 13.** Anteroposterior view of knee radiographs showing successful case of a CR implant.

Cruciate-Retaining Total Knee Arthroplasty http://dx.doi.org/10.5772/intechopen.74024 37

**Figure 14.** Lateral view of knee radiographs showing successful case of a CR implant.

If in the past many studies argued that CR implant lead to paradoxical kinematic, more recent and relevant studies demonstrated that with new design components and well-standardized technique, the native femoral rollback is better restored with a CR-TKR than with a PS implant. International studies also confirm that the stability in all range of movement can successfully be achieved, and care must be paid to joint line position and posterior tibial slope when performing a CR replacement; in fact, they are two of the main factors that affect the tension of the retained PCL. Less femoral distal cut as possible should be executed to not compromise gap balances between extension and flexion: in fact, the retention of the PCL lead to a smaller space in flexion than what obtained with PCL recession, but if more space is needed in flexion (caused by a too thigh PCL), creating a more sloped tibial cut may help to reduce tension on the PCL-facilitating knee flexion.

The main criticism of the surgical technique is that the distal attachment of the PCL is vulnerable to injury during the tibial resection and the creation of a bone island through the use of an osteotome and a pin in front of the ligament can protect it from a damage that could seriously cause difficulties in balancing; balancing a PCL, especially in case of severe deformities, can be difficult but many tests and solution have been successfully proposed to understand and solve different complex combinations (**Figures 13** and **14**).

We think that performing a CR-TKR is difficult and requires a long learning curve, but at the same time with a standardized technique, it is always possible to prefer this type of implant even in those case wherein many surgeon would prefer a PS implant: considering that more and more young high-demanding patients are subjected to this procedure you should preserve

**Figure 13.** Anteroposterior view of knee radiographs showing successful case of a CR implant.

geometry in the sagittal plane. Increasing posterior slope for the tibial resection will relax the PCL. Posterior tibial slope typically should not exceed 10° to avoid risk of injury to the tibial attachment of the PCL. Posterior cruciate recession consists of selective release of the anterior fibers of the PCL from their tibial attachment. Release of the anterior 10–20% of the PCL can often help achieve the correct soft tissue balance. If greater than 75% of the PCL is released, some feel a PCL-substituting prosthesis should be considered. The concern in those cases is that the remaining 25% of the PCL fibers may rupture later with activity, leading to flexion instability. If the PCL is released or absent, the tibial tray should be more conforming because rollback does not occur. Hence, the surgeon should match the constraints of the soft tissue

A knee that is tighter in flexion requires one or a combination of maneuvers that include PCL release, downsloping the tibial resection, downsizing the femoral component, or additional tibial resection with distal advancement of the femoral component. A knee that is tighter in

The most recent literature and National Joint registries confirm that CR-TKR has good clinical

If in the past many studies argued that CR implant lead to paradoxical kinematic, more recent and relevant studies demonstrated that with new design components and well-standardized technique, the native femoral rollback is better restored with a CR-TKR than with a PS implant. International studies also confirm that the stability in all range of movement can successfully be achieved, and care must be paid to joint line position and posterior tibial slope when performing a CR replacement; in fact, they are two of the main factors that affect the tension of the retained PCL. Less femoral distal cut as possible should be executed to not compromise gap balances between extension and flexion: in fact, the retention of the PCL lead to a smaller space in flexion than what obtained with PCL recession, but if more space is needed in flexion (caused by a too thigh PCL), creating a more sloped tibial cut may help to reduce tension on

The main criticism of the surgical technique is that the distal attachment of the PCL is vulnerable to injury during the tibial resection and the creation of a bone island through the use of an osteotome and a pin in front of the ligament can protect it from a damage that could seriously cause difficulties in balancing; balancing a PCL, especially in case of severe deformities, can be difficult but many tests and solution have been successfully proposed to understand and

We think that performing a CR-TKR is difficult and requires a long learning curve, but at the same time with a standardized technique, it is always possible to prefer this type of implant even in those case wherein many surgeon would prefer a PS implant: considering that more and more young high-demanding patients are subjected to this procedure you should preserve

with the inherent constraints of the knee system being used [1].

results and excellent intermediate and long-term survival.

solve different complex combinations (**Figures 13** and **14**).

**10. Conclusion**

36 Primary Total Knee Arthroplasty

the PCL-facilitating knee flexion.

extension is usually corrected merely by added distal femoral resection [1].

**Figure 14.** Lateral view of knee radiographs showing successful case of a CR implant.

as much as possible the ligamentous structures for their physiological function and avoid bone cuts as much as possible (in the CR designs, the creation of the intercondylar notch resection is not required) in the perspective of a possible revision in the future.

[8] Verra WC, van den Boom LGH, Jacobs W, Clement DJ, Wymenga AAB, Nelissen RGHH. Retention versus sacrifice of the posterior cruciate ligament in total knee arthroplasty for treating osteoarthritis. Cochrane Database of Systematic Reviews. 2013;(10. Art. No.:

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[9] Li N, Tan Y, Deng Y, et al. Posterior cruciate-retaining versus posterior stabilized total knee arthroplasty: A meta-analysis of randomized controlled trials. Knee Surgery, Sports

[10] Bercik Michael J et al. Posterior cruciate-retaining versus posterior-stabilized total knee arthroplasty. The Journal of Arthroplasty;**28**(3):439-444. DOI: 10.1016/j.arth.2012.08.008

[11] Stiehl JB, Komistek RD, Dennis DA, Paxson RD, Hoff WA. Fluoroscopic analysis of kinematics after posterior-cruciate-retaining knee arthroplasty. Journal of Bone and Joint

[12] Insall & Scott—Surgery of the Knee, 5th Edition. Edited by W. Norman Scott. Published

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[14] Bertin KC, Komistek RD, Dennis DA, Hoff WA, Anderson DT, Langer T. In vivo determination of posterior femoral rollback for subjects having a NexGen posterior cruciateretaining total knee arthroplasty. The Journal of Arthroplasty. 2002;**17**(8):1040-1048 [15] Sierra RJ, Berry DJ. Surgical technique differences between posterior-substituting and cruciate-retaining total knee arthroplasty. The Journal of Arthroplasty. 2008;**23**(7 Suppl):1

[16] Kang K-T, Koh Y-G, Son J, Kwon O-R, Lee J-S, Kwon S-K. Influence of increased posterior tibial slope in total knee arthroplasty on knee joint biomechanics: A computational simulation study. The Journal of Arthroplasty. 2018 Feb;**33**(2):572-579. DOI: 10.1016/j.

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Finally, for severe deformities associated with ligamentous laxity, the debate about preserve or resect the PCL is out of place: in these cases, the solution should be finding in a CR or PS TKR but in a more constrained implant.
