A comparison of the proprioception of osteoarthritic knees and post total knee arthroplasty

INTRODUCTION

Proprioception is a word coined in the 1890 to explain the sensations of the joint that become stimuli for our brain to perceive the whereabouts of our joints and body. It originates from “proprius” which means one’s own. The standard definition of proprioception is the reception of stimuli produced in (an organism). Sir Charles Bell claimed limb position and motion to be the sixth sense after the 5 original senses as explained by Aristotle.

These sensations are said to be mediated by receptors called mechanoreceptors and free nerve endings. The mechanoreceptors are of various types some of which reside in the joint capsule and ligaments, and some in the musculotendinous junction.¹

There is a substantial amount of evidence that shows the importance of proprioception for production of smooth, controlled and coordinated movements, maintenance of posture and motor learning and relearning. Some studies showed that deafferented patients had delayed movements and an inaccurate trajectory of movement.^2,3

The association of proprioception deficits and osteoarthritis is undeniable but what is still unclear is which on is the result of which i.e. is the proprioceptive deficit a part of the etiology or the pathologic process? A longitudinal study with a large cohort failed to demonstrate that proprioceptive deficit is a risk factor for the development or progression of knee Osteoarthritis.⁴

Researchers supporting PCL-retaining TKA system argue that in the regular knee joint kinematics physiologic roll-back mechanism is preserved and adding that of the neurosensory properties when PCL is preserved, it is an advantage for the patients.⁵

METHODS

We included 80 primary unilateral knee replacements with osteoarthritis on the contralateral limb. All patients with morbid obesity (BMI >30) uncontrolled diabetes, neurological disorders or those who lacked mental capacity and cooperation. All the surgeries were performed by the same surgeon and the decision to do a PCL retaining or a PCL substituting knee was decided prior to the surgery.

The study was conducted in Sri Ramachandra University, Chennai from August 2015 to September 2016.

We assessed proprioception by conscious awareness of passive joint position and threshold to detection of passive motion.

The first method we used was of conscious awareness of passive joint position assessment. We performed a reproduction of passive motion by using a CPM Machine (knee flex) with a transducer to show the digital angle on a connected handheld device. The patient was blindfolded and given a noise cancelling headset (3 M). We demonstrated a position of 45⁰ three times, for 10 seconds at a time. This would allow the slow adapting Ruffini corpuscles in the ligaments to adapt, and hence lead to memory of the joint position.⁶

Next the knee joint was bought to a relatively extended position and flexed as per CPM machine at a angular velocity of rate of 1⁰ per second. The patient was asked to press the button on the handset or incase that was difficult, to make a Hand signal when they so perceived the angle of 45⁰. The angle 45 was chosen as to not put tension on the joint capsule. The difference of the perceived versus actual position showed on the handheld device, and the mean of the three trials were taken. This test was done for both the replaced knee and the contralateral non-operated osteoarthritic knee.

The second factor that we checked was Threshold to detection of passive motion. We placed the knee at 45⁰ flexed positions and started to flex the knee slowly at a rate of 1⁰ per second and as soon as the patient recognized the movement of his knee, he would as done prior, raise his hand or press the stop button on the handheld device. This test was performed for both the operated and non-operated osteoarthritic knee (Table 2).

The results were measured with Mann Whitney test and paired sample statistics on statistical tool SPSS (IBM).

RESULTS

73.8% (n =59) of patients with knee prostheses experienced a better proprioceptive ability, 21% (n =17) had decreased proprioceptive function and 5% (n =4) had the same proprioceptive function when compared to the opposite osteoarthritic knee.

We noticed that 67.5% of patients with cruciate retaining implants had an improved Joint position sense compared with the contralateral non-operative osteoarthritic knee. 80% of patients with posterior stabilized knees had an improved joint position sense compared with contralateral osteoarthritic knee.

The Mean value for threshold to detection of passive motion of non-operated osteoarthritic knees was 2.72 ⁰ with a standard deviation of 0.619 and that of operated knees was 2.16⁰ with a standard deviation of 0.685. There was significant p value of 0.005.

We also compared the mean value of threshold to detection of passive motion for cruciate retaining implant which was 2.13⁰±0.72 to that of posterior stabilized implants with 2.20⁰±0.64 degrees with an insignificant p value of 0.668.

DISCUSSION

We will discuss about posterior stabilized and cruciate retaining total knee replacements under 2 parameters. The first one being a mean difference in joint position sense from the reference point and the second a threshold to detection of passive motion.

We compared the mean difference in joint position sense of the knee replacement on one side versus the contralateral osteoarthritic knee. There was a significantly better proprioception in the group for which total knee replacement was done. There was an improvement in joint position sense of 73.8% (n =59) of our patients who underwent knee arthroplasty. We also compared the cruciate retaining implants versus the posterior stabilized patients, 67.5% of cruciate retaining implants had a better joint position sense whereas, 80% of the posterior stabilized knees showed a better proprioception when compared to the contralateral non-operative osteoarthritic side. This was probably indicative of the higher grades of osteoarthritis in those opposite knees, as the more severe initial osteoarthritis, the worse the proprioceptive deficit is. The other reasons for a possible restoration of joint sensation after total knee arthroplasty could be elimination of deleterious factors in elderly and osteoarthritic factors.^7,8

This was similar to the study by Simmons et al. who when performing threshold to detection of passive motion. They reported nearly identical postoperative scores in those with modest arthritis whereas those with initial severe preoperative arthritis performed better with cruciate sacrificing implants.⁹ This was a surprise to them and they hypothesised that any proprioception originating in the cruciate ligaments was lost in early degenerative process, as also shown by Kleinbart histologically.¹⁰

Mean difference in joint position sense from the reference point. In our study, the mean difference from the reference point for passive reproduction of joint position or joint position sense was 2.58 degrees with a standard deviation of 1.85 degrees for those with cruciate retaining implants and 2.11 degrees with a standard deviation of 1.18 degrees for those with posterior stabilized implants, but the p value was 0.183 which was insignificant.

Thus in our study there was no difference in the joint position sense for either the posterior cruciate retaining or sacrificing/substituting implants.

This is comparable to Swanik and others who showed when PCL retention was compared to the patients with posterior stabilized total knee design there was no significant improvement in proprioception in Table 5.⁷

This however is not indicative of a lack of proprioceptive benefit of the posterior cruciate ligament. Warren et al reported a comparative study of 20 PCL Retaining and 20 PCL substituting TKA’s and concluded knees in which the PCL was retained had a greater improvement in joint position sense.¹¹

This is in contradiction to the study by Ishii et al. They investigated the joint position sense before and after TKA on patients with semi constrained total knee arthroplasty, and stratified the knees into those that are semi constrained and into those with or without remaining posterior cruciate ligaments. They reported that there was no significant improvement of joint position sense among all the arthroplasty groups and concluded that the knee arthroplasty did not affect joint position sense.¹²

Threshold to detection of passive motion

The non-operative osteoarthritic knees had a mean threshold to detection of 2.70±0.608 compared to the operated knees 2.13±0.723. There was a difference in the mean values of the operated knees and the non-operated osteoarthritic knees with a significant p value of <0.005. This is similar to the study by Swanik et al which showed a level of better proprioception of postoperative knees compared to that of preoperative knees.⁷

This was in contradiction to Cash et al. showed that substitution or retention of the PCL made no clinical difference in proprioception as measured by testing threshold to passive motion.¹³ The report by Simmons et al has a similar conclusion. They compared unicondylar and total knees with and without PCL retention using threshold to detection of motion. He reported no difference in values across the three groups, suggesting that PCL retention had no advantage in the betterment of proprioception.

In our study, the mean threshold for detection of motion for the implants with cruciate retaining was 2.13±0.723 and that of posterior stabilized was 2.20±0.648. There was an insignificant p value for the difference. This is comparable to Swanik’s value of postoperative 1.66±0.99. There was no difference in our values which indicated no proprioceptive difference between the posterior stabilized and cruciate retaining implants in concert with Swanik et al.⁷

Limitations

There were a few limitations in our study:

The first of which was that the study was a cross sectional study, assuming the contralateral non-operative osteoarthritic knee to be indicative of the preoperative osteoarthritic knee.

The second limitation was the method of checking the passive reproduction of motion with continuous passive motion, while being the closest technically sound substitute for the evaluation of passive motion, there was also a flexion of the hip occurring simultaneously, which despite being checked to be normal may have been a variable.

The third limitation was that we require a long term follow up to assess the continued function of the posterior cruciate ligament in cruciate retaining prosthesis as the age progresses.

CONCLUSION

There was an increased accuracy of passive reproduction of joint position and a better threshold to detection of passive motion in the replaced knees when compared with the contralateral non-operative osteoarthritic knees, which indicates an improvement of proprioception post knee replacement.

The second conclusion was that there was no difference in passive reproduction of joint position or threshold to detection of passive motion among both the cruciate retaining and cruciate substituting groups, which suggests no difference in proprioception between them.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the institutional ethics committee

REFERENCES

1. 1. The physiology of mechanoreceptors - Prentice W. Rehabilitation techniques in sports medicine. St. Louis: Mosby; 1994.
2. 2. Ribiero F, Oliveria J. Factors influencing proprioception: What do they reveal?? Biomechanics in med applications. In: Tech Croatia. 2011: 323-346.
3. 3. Sarlegna FR, Sainburg RL. The roles of vision and proprioception in planning of reaching movements. Adv Med Biol. 2009;629:317-35.
4. 4. Felson DT, Gross KD, Nevitt MC, Yang M, Lane N, Torner J. The effects of impaired joint position sense on the development and progression of pain and structural damage in knee osteoarthritis. Arthritis Rheum. 2009;61(8):1070-6.
5. 5. Sorger JI, Federle D, Kirk PG, Grood E, Cochran J. The posterior cruciate ligament in total knee. J Arthroplasty. 1997;12(8):869-79.
6. 6. Lephart S, Pincivero D, Giraido J, Fu F. The Role of Proprioception in the Management and Rehabilitation of Athletic Injuries. Am J Sports Med. 1997;25(1):130-7.
7. 7. Swanik CB, Lephart SM, Rubash HE. Proprioception, kinesthesia, and balance after total knee arthroplasty with cruciate-retaining and posterior stabilized prostheses. J Bone Joint Surg Am. 2004;86:328–34.
8. 8. Franchi A, Zaccherotti G, Aglietti P. Neural system of the human posterior cruciate ligament in osteoarthritis. J Arthroplasty. 1995;10:679-82.
9. 9. Simmons S, Lephart S, Rubash H, Borsa P, Barrack R. Proprioception following total knee arthroplasty with and without the posterior cruciate ligament. J Arthroplasty. 1996;11(7):763-8.
10. 10. Kleinbart F, Bryk E, Evangelista J, Scott W, Vigorita V. Histologic comparison of posterior cruciate ligaments from arthritic and age-matched knee specimens. J Arthroplasty. 1996;11(6):726-31.
11. 11. Warren PJ, Olanlokun TK, Cobb AG, Bentley G. Proprioception after knee arthroplasty. The influence of prosthetic design. Clin Orthop Relat Res. 1993;297:182-7.
12. 12. Ishii Y, Terajima K, Terashima S, Bechtold J, Laskin R. Comparison of joint position sense after total knee arthroplasty. J Arthroplasty. 1997;12(5):541-5.
13. 13. Cash R, Gonzalez M, Garst J, Barmada R, Stern S. Proprioception After Arthroplasty. Clinical Orthop Relat Res. 1996;331:172-8.
14. 14. Attfield SF, Wilton TJ, Pratt DJ, Sambatakakis A Soft-tissue balance and recovery of proprioception after total knee replacement. J Bone Joint Surg Br. 1996;78:540-5.
15. 15. Barrett DS, Cobb AG, Bentley G. Joint proprioception in normal, osteoarthritic and replaced knees. J Bone Joint Surg Br. 1991;73(1):53-6.
16. 16. Lattanzio P, Chess D, Mac Dermid J. Effect of the posterior cruciate ligament in knee-joint proprioception in total knee arthroplasty. J Arthroplasty. 1998;13(5):580-5.
17. 17. Wada M, Kawahara H, Shimada S, Miyazaki T, Baba H. Joint Proprioception Before and After Total Knee Arthroplasty. Clin Orthop Relat Res. 2002;403:161-7.