|Year : 2022 | Volume
| Issue : 2 | Page : 61-65
Comparison of the functional outcome of posterior cruciate-retaining versus posterior cruciate-sacrificing total knee arthroplasty
Mohit Kumar Issrani, Harsh Kotecha, Dhruv Shah, Alfven Vieira, Shahish Surme, Laksh Agrawal
Department of Orthopaedics, MGM Medical College and Hospital, Navi Mumbai, Maharashtra, India
|Date of Submission||10-Dec-2021|
|Date of Decision||16-Jan-2022|
|Date of Acceptance||21-Jan-2022|
|Date of Web Publication||28-May-2022|
Mohit Kumar Issrani
208, PG Hostel, MGM Medical College and Hospital, Kamothe, Navi Mumbai - 410 209, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: Although being debated for many years, the superiority of either posterior cruciate-retaining (CR) total knee arthroplasty (TKA) and posterior-stabilized (PS) TKA remains controversial. Materials and Methods: We conducted a prospective study on 40 knee replacements which were undertaken at our hospital between July of 2020 and July of 2021 out of which in 30 patients the cruciate ligament was sacrificed and the posterior cruciate ligament was retained in 10 of the knees undergoing surgery. The inclusion criteria were patients of age more than 50 years, with osteoarthritis and rheumatoid arthritis and Kellgren and Lawrence Grade of 3 and 4. The posterior cruciate ligament was retained if it was structurally intact, fixed flexion deformity of <15° a varus or valgus deformity of <10°. The overall average knee score was 84.9 for posterior cruciate-sacrificing and 74.6 for the CR patients as compared to the preoperative score of 43.9 and 37.6. Functional Knee Score was 97.87 and 98.4 for the CS and CR groups, respectively. The preoperative Functional Knee Score was 37.1 and 37.8 in these groups. The WOMAC Score also showed a marked improvement from 67.7 to 24.6 and 27.4 for CS and CR, respectively. Results and Conclusions: Analyzing the total knee scores, the average Knee Society Score for the PS group was 84.90 and that of the CR group was 74.60 and statistical analysis revealed a significant difference in the P value in favor of cruciate-sacrificing prosthesis, signifying that cruciate-sacrificing prosthesis has better functional outcome. The WOMAC Score also showed a marked improvement. In the CS group, it was 24.6, and in the CR group, it was 27.4. Statistical analysis showed a highly significant difference in favor of cruciate-sacrificing prosthesis.
Keywords: Arthroplasty, cruciate retaining, cruciate sacrificing, knee, total knee arthroplasty
|How to cite this article:|
Issrani MK, Kotecha H, Shah D, Vieira A, Surme S, Agrawal L. Comparison of the functional outcome of posterior cruciate-retaining versus posterior cruciate-sacrificing total knee arthroplasty. J Orthop Dis Traumatol 2022;5:61-5
|How to cite this URL:|
Issrani MK, Kotecha H, Shah D, Vieira A, Surme S, Agrawal L. Comparison of the functional outcome of posterior cruciate-retaining versus posterior cruciate-sacrificing total knee arthroplasty. J Orthop Dis Traumatol [serial online] 2022 [cited 2023 Jun 6];5:61-5. Available from: https://jodt.org/text.asp?2022/5/2/61/346216
| Introduction|| |
Although being debated for many years, the superiority of either posterior cruciate-retaining (CR) total knee arthroplasty (TKA) and posterior-stabilized (PS) TKA remains controversial. With the posterior cruciate ligament (PCL) retained, CR TKA was thought to be better regarding postoperative knee proprioception and kinesthesia., While others believed that PS TKA had better range of motion (ROM), easier in ligament balance, and more reliable femoral rollback., The posterior translation of the femur creates more clearance over the tibia and, theoretically, more flexion.
We conducted a prospective study to compare resection with retention of PCL using a standard PCL-retaining cemented total knee replacement and assessed the functional outcome using Functional Knee Scores and Western Ontario and McMaster Universities Arthritis Index (WOMAC) Score during the period between July 2020 and July 2021.
| Materials and Methods|| |
- Osteoarthritis and rheumatoid arthritis
- Age >50 years
- Kellgren and Lawrence score Grade 3 and 4.
- Age <50 years
- Minimal degenerative changes (Kellegran and Lawrence I and II)
- Poor skin conditions
- Posttraumatic arthritis
- Varicose veins
- Medically unfit
- Patients without documents for scheme.
Criteria for retaining posterior cruciate ligament
- Structurally intact PCL
- Fixed flexion deformity of <15°
- Varus of <10°
- Valgus of <10°.
Criteria for sacrificing posterior cruciate ligament
- Fixed flexion deformity of more than 15°
- Valgus or varus more than 10°
- Structurally contracted PCL
- Technical inability to properly balance PCL.
The period of study is from July 2020 to July 2021. Cases operated before July 2020 with at least 3 months of follow-up were taken into study. During the study period, 52 knees were replaced in 50 patients. Of them, six patients with six total knee replacements were lost to follow-up. Two died due to medical causes and four did not turn up for follow-up. Others had regular follow-up and were taken into the study. The final study was on 40 knees in 38 patients which include 2 bilateral and 36 unilateral cases. The patients who did not turn for follow-up were excluded from the study. This included ten patients with ten knees.
All the cases were done under tourniquet control using pneumatic tourniquet. Spinal and Epidural anaesthesia administered. All cases were approached by an anterior midline incision and retinacular exposure done by medial parapatellar arthrotomy. Ligament balancing and bone cuts were performed on table depending on the severity of the disease using cutting blocks and balancing jigs and trial implants were used to confirm the ROM, correction of deformity, and stability of the replaced knee joint. PCL was retained in ten patients who had minimal deformities with no flexion contracture preoperatively, and PCL was sacrificed in rest of the patients. PCL-retaining prosthesis (CR) was applied for all the ten in whom PCL was retained. Implants for all the 40 cases were of the same manufacturer. Bone cement was used in all the 40 cases for implanting the final femoral and tibial components. Patients were made to walk on the same day in the evening according to pain tolerance.
Postoperative evaluation: Clinical/functional
Postoperative follow-up was done monthly during the initial 3 months. All patients were evaluated postoperatively for the range of movement, relief of pain and scoring done as per Knee Society Score, knee functional score and WOMAC Questionnaire was done in all patients after an average of 3 months from the date of surgery.
| Results|| |
All the 40 cases which had regular follow-up were taken into the study, and the average follow-up was from a minimum of 3 to 18 months.
We had the following observations:
Among the 40 cases which received total knee replacement, we retained PCL in 10 patients, and in the rest, it was sacrificed.
The functional outcome between the posterior CR and the cruciate-sacrificing groups was compared using the American Knee Society Scoring and the Functional Knee Score and WOMAC Questionnaire, and the following observations were made.
Overall all the patients in both the groups had a great improvement in the knee scores. The pain score (including stair climbing) in the posterior cruciate sacrificing was on average 41.9 (out of 50) and that of the CR group was 38. Stair-climbing score was 11.0 (out of 15) and 9.1 in the PCL-sacrificing and PCL-retaining groups, respectively, as compared to the preoperative score of 4.6 and 5.1 [Figure 1] and [Table 1].
Range of movements
The mean range of movements in the CS and CR groups had a great improvement with postoperative scores of 19.7 (max 25) and 18.1 in the PCL-sacrificing and PCL-retaining groups, respectively [Figure 2] and [Table 2].
Total knee scores
The overall average knee score was 84.9 for posterior cruciate-sacrificing and 74.6 for the CR patients as compared to the preoperative score of 43.9 and 37.6. Functional Knee Score was 97.87 and 98.4 for the CS and CR groups, respectively [Figure 3], [Figure 4] and [Table 3], [Table 4].
The preoperative Functional Knee Score was 37.1 and 37.8 in these groups. The WOMAC Score also showed a marked improvement from 67.7 to 24.6 and 27.4 for CS and CR, respectively [Figure 5] and [Table 5], [Table 6].
| Discussion|| |
Total knee replacement is a surgical procedure to resurface the intra-articular weight bearing surfaces of the knee joint. The main indication for a total knee replacement is pain followed by restriction of movement and deformity. The most common indication for total knee replacement is osteoarthritis of the knee and rheumatoid arthritis of the knee.
The mean age of the patients getting operated for total knee replacement at our center was 60 years of age. This is much higher than the western world. The early onset of arthritis in the Indian population (if normal BMI) is owing to the lifestyle of squatting, sitting on the floor cross legged and kneeling.
The results were analyzed statistically using SSPS (Statistical Package for the Social Sciences) version 17 IBM Technologies (IBM Inc, Armonk, New York, USA )software and using:
- Chi-square for discrete variables
- t-test for continuous variables
- Bivariate correlation to find out the measure of agreement.
All patients in the study in both the groups had marked relief in their pain scores from their pre-operative level. The pain score of knee society score were analysed statistically and we got the following values.
Range of movements
We were able to achieve a flexion of up till nearly 110° in all our patients post surgery, and statistically, there was not much difference between the CR and CS groups.
The pain score showed a marked improvement in all the patients with an average of 41.9 in the CS group as compared to 38 in the CR group. Statistical analysis revealed a significant difference in P value for all the variables of pain score (walking, climbing which was in favor of the cruciate-sacrificing group signifying that they had a better improvement in pain score).
Analyzing the total knee scores, the average Knee Society Score for the PS group was 84.90 and that of the CR group was 74.60 and statistical analysis revealed a significant difference in the P value in favor of cruciate-sacrificing prosthesis, signifying that cruciate-sacrificing prosthesis has better functional outcome.
The Functional Knee Society also showed a marked improvement in all patients; for the CS group, FKS was 97.87, and for the CR group, it was 98.4. Statistically, there was no significant difference.
The WOMAC Score also showed a marked improvement. In the CS group, it was 24.6, and in the CR group, it was 27.4. Statistical analysis showed a highly significant difference in favor of cruciate-sacrificing prosthesis.
Moreover, when the three scoring systems were evaluated in our study, we found a good agreement between each scoring system with one other.
- All patients had a marked improvement in their Knee Society Score and the increase was attributed to pain score and stair climbing
- Functional Knee Score showed an excellent improvement in all the patients
- WOMAC Score also showed a marked improvement with a significant improvement in patients in whom PCL was sacrificed
- There exists a good degree of agreement between the Knee Society Score, Functional Knee Score, and WOMAC Score.
The debate over the relative merits of substituting or retaining the PCL in TKA is still a heavily contested one. The potential advantages of PCL preservation (CR surgeries) are a more natural femoral rollback, increased proprioception, presence of a critical stabilizing structure of the knee joint, and a decreased shearing stress on the bone–cement interface of the tibial component. Numerous retrospective studies of CR total knee replacement have demonstrated consistently good clinical results and excellent intermediate and long-term survival. The main criticisms of CR knees are that the distal attachment of the PCL is susceptible to injuries and that PCL balancing can become difficult intraoperative.
Conversely, proponents of PS designs argue that substituting the PCL with a post and cam improves ROM secondary to mechanical enforcement of femoral rollback., The posterior translation of the femur creates more clearance over the tibia and, theoretically, more flexion.
Our findings suggest that there is a difference in the mean ROM and flexion between CR and PS designs that favor PS designs. The clinical implications of this difference are still unclear. Ritter et al. showed a general trend of improved functional scores with greater ROM, with significant compromise below 118°. Many functional activities of daily life do not require such severe knee ranges of motion, for example, in stair climbing requirement is about 90°. In our Indian societies, however, where squatting and sitting cross-legged are more common culturally, flexion demands may go as high as 111°–165°. Intuitively, it makes sense that a knee replacement that more closely replicates the natural knee in terms of ROM would best serve the patient's functional demands, albeit at the potential risk of increased stress to the implant and overall longevity. What is not yet known is whether the subtle differences in ROM and flexion in the ranges shown here are noticeable to the patient and clinically relevant. Furthermore, the design itself may matter less than the patient's preoperative flexion and ROM.
In 2019, Singleton et al. reported a more accurate reflection of knee kinematics and a better ROM with the uses of PS knees and had shown better short-term functional outcomes, specifically with respect to the knee stiffness. These findings, however, did not sustain at 5 and 10 years post surgery.
| Conclusion|| |
Our data show a statistically significant trend of reduced pain, greater flexion, and ROM and a better Functional Knee Score achieved with PS cruciate-sacrificing total knee prostheses. However, the advantage is not great and may fall in a range that may not be clinically significant. Since both total knee designs have shown excellent long-term results, there may not be much point in arguing for one design over the other.
- TKA in patients in whom PCL was sacrificed was found to have a better functional outcome as compared to the retaining group
- In Indian scenario where knee replacement is done at a late stage of osteoarthritis, sacrificing the contracted PCL has better outcomes as compared to retaining it
- Finally, our study is in a small number of cases with short duration and further follow-up is necessitated.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]