Effect of the posterior cruciate ligament in knee-joint proprioception in total knee arthroplasty

Does Posterior Cruciate Ligament Retention or Sacrifice in Total Knee Replacement Affect Proprioception? A Systematic Review

Background: Proprioception is an important part of the somatosensory system involved in human motion control, which is fundamental for activities of daily living, exercise, and sport-specific gestures. When total knee arthroplasty (TKA) is performed, the posterior cruciate ligament (PCL) can be retained, replaced, or discarded. The PCL seems to be responsible for maintaining the integrity of the joint position sense (JPS) and joint kinesthesia. The aim of this review was to assess the effect of PCL on knee joint proprioception in total knee replacement. Methods: This systematic review was conducted within five electronic databases: PubMed, Scopus, Web of Science, Cochrane, and PEDro with no data limit from inception to May 2021. Results: In total 10 publications were evaluated. The analysis was divided by proprioception assessment method: direct assessment (JPS, kinesthesia) and indirect assessment (balance). Conclusions: The current evidence suggest that the retention of the PCL does not substantially improve the joint proprioception after TKA. Due to the high heterogeneity of the studies in terms of design, proprioception outcomes, evaluation methods, further studies are needed to confirm the conclusions. In addition, future research should focus on the possible correlation between joint proprioception and walking function.

Total Knee Arthroplasty in Patients With Knee Osteoarthritis: Effects on Proprioception. A Systematic Review and Best Evidence Synthesis

BACKGROUND

Impact of total knee arthroplasty (TKA) on proprioception remains to be determined. The aim of this systematic review is to analyze factors influencing proprioception in patients with knee osteoarthritis (OA) undergoing TKA.

METHODS

A systematic literature search was conducted on 3 medical electronic databases: PubMed, PeDRO, and Cochrane Collaboration. The Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines were used. Risk of bias analysis and best evidence synthesis were performed. Three main aspects were investigated: the presence of preoperative, surgical, and postoperative factors influencing proprioception in OA patients undergoing TKA.

RESULTS

Search identified 1601 records. After screening, 19 papers were used for the analysis of 676 patients. Proprioception generally improved but often remained impaired after surgery. Strong evidence was found for no influence of prosthesis design on proprioception. Moderate evidence was found for patellar resurfacing not affecting proprioception, varus deformity negatively influencing proprioception, and time elapsed from surgery positively influencing proprioception. Limited evidence was found for valgus deformity, OA grade, intact anterior cruciate ligament, and anteroposterior joint laxity negatively affecting knee proprioception, and for muscle strength and sensorimotor training not affecting proprioception. Finally, conflicting evidence was found for better postoperative proprioception vs preoperative level.

CONCLUSION

Proprioception in OA patients undergoing TKA improves but remains impaired after surgery. The best evidence synthesis demonstrated no influence of prosthetic design, while the role of the treatment remains unclear. This warrants for further research efforts to study proprioceptive impairment to better manage OA patients undergoing TKA.

Slow gait speed after bilateral total knee arthroplasty is associated with suboptimal improvement of knee biomechanics

PURPOSE

The aim of this study was to investigate gait speed changes 2 years after bilateral total knee arthroplasty (TKA) and identify kinetic and kinematic factors associated with such changes by comparing patients with age- and sex-matched controls.

METHODS

The study group included 34 female patients with end-stage knee osteoarthritis (OA) who underwent bilateral TKA and 42 age- and sex-matched controls without knee pain or OA. Standard TKA was performed on all arthritic patients with placement of posterior stabilized fixed-bearing implants. Kinetic and kinematic parameters were evaluated using a commercial optoelectric gait analysis system. Gait speed, kinetic and kinematic changes and determinants of speed were assessed via principal component analysis and multiple regression analysis.

RESULTS

The average gait speed of an arthritic patient was 90.2 ± 18.4 cm/s and improved to 96.0 ± 12.3 cm/s after TKA (p = 0.032). However, the speed remained slower than that of controls (111.2 ± 8.2 cm/s, p < 0.001). With regard to kinetics, the peak knee extension moment (KEM) generated by the quadriceps was unchanged after TKA and weaker than that of controls (p < 0.001). The proportions of KEM contributing to the total sagittal moment were also smaller in the pre-/post-operative groups than in the control group (13-14% vs. 19%). On the other hand, the ankle plantar flexion moment (APFM) was increased after TKA (p = 0.007) and its proportion of the total sagittal moment was greater than in controls (46% vs. 42%). With regard to kinematics, knee range of motion (ROM) improved after TKA (p = 0.025), but was smaller than that of controls (p < 0.001). In controls, gait speed was determined principally by hip and knee joint moments. However, in the TKA group, speed was determined by the knee ROM and APFM.

CONCLUSIONS

Despite showing improvement, the gait speed of TKA patients remained slower than that of controls. Slow gait speed after bilateral TKA was associated with suboptimal improvement of knee biomechanics. Quadriceps strengthening exercises and the achievement of greater ROM during gait are advised for the further improvement of gait speed.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

Does cruciate retention primary total knee arthroplasty affect proprioception, strength and clinical outcome?

PURPOSE

It remains unclear what the contribution of the PCL is in total knee arthroplasty (TKA). The goal of this study was to investigate the influence of the PCL in TKA in relationship to clinical outcome, strength and proprioception.

METHODS

Two arthroplasty designs were compared: a posterior cruciate-substituting (PS) and a posterior cruciate-retaining (CR) TKA. A retrospective analysis was performed of 27 CR and 18 PS implants with a minimum of 1 year in vivo. Both groups were compared in terms of clinical outcome (range of motion, visual analogue scale for pain, Hospital for Special Surgery Knee Scoring system, Lysholm score and Knee Injury and Osteoarthritis Outcome Score), strength (Biodex System 3 Dynamometer(®)) and proprioception (balance and postural control using the Balance Master system(®)). Each design was also compared to the non-operated contralateral side in terms of strength and proprioception.

RESULTS

There were no significant differences between both designs in terms of clinical outcome and strength. In terms of proprioception, only the rhythmic weight test at slow and moderate speed shifting from left to right was significant in favour of the CR design. None of the unilateral stance tests showed any significant difference between both designs. There was no difference in terms of strength and proprioception between the operated side and the non-operated side.

CONCLUSION

Retaining the PCL in TKA does not result in an improved performance in terms of clinical outcome and proprioception and does not show any difference in muscle strength.

LEVEL OF EVIDENCE

III.

Immunohistochemical analysis of the neural structures of the posterior cruciate ligament in osteoarthritis patients submitted to total knee arthroplasty: an analysis of thirty-four cases

OBJECTIVES

Many authors recommend posterior cruciate ligament-retaining arthroplasty with the intention to maintain the proprioception properties of this ligament. Preservation of the neuroreceptors and nervous fibers may be essential for retaining the proprioception function of the posterior cruciate ligament. The present study was thus developed to evaluate the presence of neural structures in the posterior cruciate ligament resected during posterior stabilized arthroplasty in osteoarthritis patients. In particular, clinical, radiographic and histological parameters were correlated with the presence or absence of neural structures in the posterior cruciate ligament.

METHODS

In total, 34 posterior cruciate ligament specimens were stained with hematoxylin-eosin and Gomori trichrome. An immunohistochemical analysis using antibodies against the S100 protein and neurofilaments was also performed. The presence of neural structures was correlated with parameters such as tibiofemoral angulation, histological degeneration of the posterior cruciate ligament, Ahlbäck radiological classification, age, gender and the histologic pattern of the synovial neurovascular bundle around the posterior cruciate ligament.

RESULTS

In total, 67.5% of the cases presented neural structures in the posterior cruciate ligament. In 65% of the cases, the neurovascular bundle was degenerated. Nervous structures were more commonly detected in varus knees than in valgus knees (77% versus 50%). Additionally, severe histologic degeneration of the posterior cruciate ligament was related to neurovascular bundle degeneration.

CONCLUSIONS

Severe posterior cruciate ligament degeneration was related to neurovascular bundle compromise. Neural structures were more commonly detected in varus knees. Intrinsic neural structures were detected in the majority of the posterior cruciate ligaments of patients submitted to knee arthroplasty for osteoarthritis.

Histological changes and neural elements in the posterior cruciate ligament in osteoarthritic knees

PURPOSE

To evaluate histological changes and neural elements in 100 posterior cruciate ligaments (PCLs) in patients with osteoarthritis.

METHODS

100 PCLs were obtained from a consecutive series of 46 women and 16 men aged 49 to 91 (mean, 67) years who underwent primary PCL-retaining total knee replacement for osteoarthritis. Histology was examined using conventional light microscopy. The PCLs were graded histologically in terms of parallel orientation of collagen fibres, mucoid degeneration, inflammation, and haemosiderin deposition. Histological changes were graded as normal, mild degeneration, moderate degeneration, and severe degeneration. The neural elements were assessed using immunohistochemical staining for S100 protein and neurofilaments. The histopathologist was blinded to the age, gender, and clinical and radiological grades of osteoarthritis.

RESULTS

One specimen was excluded from analysis owing to inadequate tissue. In the remaining 99 specimens, histology was normal in 72, mildly degenerative in 4, moderately degenerative in 4, and severely degenerative in 15. 76 specimens were positive for S100 protein or neurofilament or both by immunohistochemical staining, indicating the presence of neural elements.

CONCLUSION

Most knees with osteoarthritis present with viable PCLs. Retaining the PCL in total knee replacement is a good option for better kinematics, stability, and proprioception.

The proprioceptive senses: their roles in signaling body shape, body position and movement, and muscle force

This is a review of the proprioceptive senses generated as a result of our own actions. They include the senses of position and movement of our limbs and trunk, the sense of effort, the sense of force, and the sense of heaviness. Receptors involved in proprioception are located in skin, muscles, and joints. Information about limb position and movement is not generated by individual receptors, but by populations of afferents. Afferent signals generated during a movement are processed to code for endpoint position of a limb. The afferent input is referred to a central body map to determine the location of the limbs in space. Experimental phantom limbs, produced by blocking peripheral nerves, have shown that motor areas in the brain are able to generate conscious sensations of limb displacement and movement in the absence of any sensory input. In the normal limb tendon organs and possibly also muscle spindles contribute to the senses of force and heaviness. Exercise can disturb proprioception, and this has implications for musculoskeletal injuries. Proprioceptive senses, particularly of limb position and movement, deteriorate with age and are associated with an increased risk of falls in the elderly. The more recent information available on proprioception has given a better understanding of the mechanisms underlying these senses as well as providing new insight into a range of clinical conditions.

Does a mobile-bearing, high-flexion design increase knee flexion after total knee replacement?

This prospective randomised controlled double-blind trial compared two types of PFC Sigma total knee replacement (TKR), differing in three design features aimed at improving flexion. The outcome of a standard fixed-bearing posterior cruciate ligament-preserving design (FB-S) was compared with that of a high-flexion rotating-platform posterior-stabilised design (RP-F) at one year after TKR. The study group of 77 patients with osteoarthritis of the knee comprised 37 men and 40 women, with a mean age of 69 years (44.9 to 84.9). The patients were randomly allocated either to the FB-S or the RP-F group and assessed pre-operatively and at one year post-operatively. The mean post-operative non-weight-bearing flexion was 107° (95% confidence interval (CI) 104° to 110°)) for the FB-S group and 113° (95% CI 109° to 117°) for the RP-F group, and this difference was statistically significant (p = 0.032). However, weight-bearing range of movement during both level walking and ascending a slope as measured during flexible electrogoniometry was a mean of 4° lower in the RP-F group than in the FB-S group, with 58° (95% CI 56° to 60°) versus 54° (95% CI 51° to 57°) for level walking (p = 0.019) and 56° (95% CI 54° to 58°) versus 52° (95% CI 48° to 56°) for ascending a slope (p = 0.044). Further, the mean post-operative pain score of the Western Ontario and McMaster Universities Osteoarthritis Index was significantly higher in the RP-F group (2.5 (95% CI 1.5 to 3.5) versus 4.2 (95% CI 2.9 to 5.5), p = 0.043). Although the RP-F group achieved higher non-weight-bearing knee flexion, patients in this group did not use this during activities of daily living and reported more pain one year after surgery.

Posterior cruciate mechanoreceptors in osteoarthritic and cruciate-retaining TKA retrievals: a pilot study

BACKGROUND

Although normal cruciate ligaments and those in patients with osteoarthritic (OA) knees contain mechanoreceptors, it is unclear whether they are present after functioning in a cruciate-retaining total knee arthroplasty (TKA).

QUESTIONS/PURPOSES

We therefore determined if the areas occupied by mechanoreceptors in the human posterior cruciate ligament (PCL) are similar in patients with osteoarthritis and in patients who have had TKA with retention of the PCL.

METHODS

We identified five cruciate-retaining TKA specimens from a retrieval program and obtained five PCLs during cruciate-sacrificing TKA from patients with OA; the retrieved specimens had been in place 5 to 12 years. The whole en bloc PCL specimens were harvested for the study. These specimens were then sectioned to a thickness of 8 μm and mounted on microscope slides. Two transverse cross-sections from the distal third from each specimen 100 μm apart were then subjected to immunohistochemistry with neurofilament protein (NFP) and S-100 protein.

RESULTS

All five PCL specimens in each group revealed multiple areas of positive stained elements with both S-100 protein and NFP immunohistochemical staining. Morphologically, these elements appear to correspond to Pacinilike, Golgilike, and fusiform types of mechanoreceptors. We observed no difference in positive staining mechanoreceptor elements as a percentage of area in the osteoarthritis and TKA groups.

CONCLUSION

Mechanoreceptors appear to occupy similar areas before and after implantation of a TKA.

CLINICAL RELEVANCE

If mechanoreceptors continue to function after cruciate-retaining TKA, then it may continue to participate in proprioception of the knee after TKA.

Mechanoreceptors found in a posterior cruciate ligament from a well-functioning total knee arthroplasty retrieval

Histologic analysis of the posterior cruciate ligament has been reported in the normal and osteoarthritic knee but not after cruciate-retaining (CR) total knee arthroplasty (TKA). Retention of the posterior cruciate ligament during TKA has been debated as to whether it is beneficial in stability and function. If the presence of mechanoreceptors is shown to be maintained in CR TKA, then there may be an argument for retention. This case report used a retrieval of a well-functioning TKA specimen that had a CR TKA. To prove the presence of mechanoreceptors within the ligament, immunohistochemistry techniques using S100 protein and neurofilament protein were used. This specimen had pacini and lamellar type of mechanoreceptors present on immunohistochemistry analysis. The presence or retention of mechanoreceptors and innervations of the ligament may indicate an advantage when retained during TKA.

Altérations architecturales et neuromusculaires du muscle vastus lateralis chez des patients âgés atteints de gonarthrose unilatérale

AIM

The aim of this study was to determine the mechanisms involved in muscle weakness in elderly patients with unilateral knee osteoarthritis.

SUBJECTS

We investigated 7 patients with unilateral knee osteoarthritis.

METHOD

We measured knee position sense and isometric maximal voluntary contraction (MVC) of the knee extensors. Electromyographic (EMG) measurement of biceps femoris (BF), rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) involved different levels of contraction (25, 50, 75 and 100% MVC). Neuromuscular efficiency of quadriceps was also calculated (MVC/EMG). Ultrasonography was used to investigate the VL architectural parameters at the median part of the VL for different levels of contraction (25, 50, and 75% MVC). All tests were performed on the osteoarthritic and healthy knees.

RESULTS

The quadriceps MVC of the affected knee was reduced by 30%. The VL thickness of the affected knee was 10% smaller than that of the unaffected knee. VL activity seen on EMG did not differ between knees, but RF, VM and BF activity was greater in the unaffected than affected knee. Neuromuscular efficiency was higher (26%) in the unaffected knee. Knee position sense was reduced by 33% in the affected knee.

CONCLUSION

Quadriceps weakness associated with knee osteoarthritis seems to be related to changes in muscle rather than pennation angle and changes in fascicule length.

Anteroposterior glide versus rotating platform low contact stress (LCS) knee arthroplasty: a randomised controlled trial

Background

Fifty thousand knee replacements are performed annually in the UK at an estimated cost of £150 million. Post-operative improvement depends on a number of factors including implant design and patient associated factors. To our knowledge there are no published study's comparing the results of AP glide and rotating platform designs of LCS knee arthroplasty. Therefore we feel that a study is required to investigate and compare the effects of two types of LCS total knee arthroplasty on joint proprioception and range of motion.

Methods/Design

Patients will be randomised to receive either a LCS AP glide or Rotating platform prosthesis. Clinical scores (Oxford knee score, American knee society score, EuroQol), range of motion and proprioception will be assessed prior to and at 3,6, 12 and 24 months after the operation. Proprioception will be assessed in terms of absolute error angle (mean difference between the target angle and the response angle). Knee angles will be measured in degrees using an electromagnetic tracking device, Polhemus 3Space Fastrak that detects positions of sensors placed on the test limb. Student's t-test will be used to compare the mean of two groups.

Discussion

Evidence is lacking concerning the best prosthesis to use for patients undergoing total knee replacement. This pragmatic randomised trial will test the null hypothesis that anteroposterior glide LCS knee arthroplasty does not result in better post operative knee motion and proprioception as compared to rotating platform LCS knee.

Trial Registration

ISRCTN52943804

Does arthroplasty type influence knee joint proprioception? A longitudinal prospective study comparing total and unicompartmental arthroplasty

Proprioception was assessed after knee replacement to compare total (TKA) to unicompartmental (UKA) knee arthroplasty. Thirty-four patients were recruited; seventeen patients underwent TKA and seventeen patients underwent UKA. The patient's age was similar in both groups. Two measures of proprioception, joint position sense (JPS) and postural sway (PS) were measured. Function was assessed using the Oxford Knee Score (OKS). Measurements were taken pre-operatively and 6 months post-operatively on both the operated and contralateral leg. Pre-operatively, no differences in JPS or PS were found between groups or between limbs in either group. Post-operatively, both groups had significant improvement of JPS in the operated limb only (20% increase). The improvement in JPS was similar in both groups. PS also improved significantly in both groups although the improvement of PS in the UKA group was twice that for the TKA group. The OKS improved by a similar amount in both groups. Both UKA and TKA result in a significant improvement in proprioception. Dynamic aspects of proprioception improve more after UKA than TKA, which may explain, in part, why UKA patients have superior functional outcome to that of TKA patients.

Proprioceptive recovery of patients with cervical myelopathy after surgical decompression

STUDY DESIGN

A prospective observational study.

OBJECTIVES

To determine whether proprioceptive deficit recovers after surgery and whether proprioceptive evaluation can predict functional outcome in cervical myelopathy patients.

SUMMARY OF BACKGROUND DATA

Proprioceptive sensation plays an important role in smooth, coordinated movement of the limbs. Information about proprioception ascends through the dorsal columns in the spinal cord. In severe compressive myelopathy, proprioceptive ability would be reduced and could be improved after surgical decompression. However, there have been few studies concerning proprioceptive impairment in cervical myelopathy.

MATERIALS AND METHODS

The study group included 26 cervical myelopathy patients who underwent posterior surgical decompression. Knee proprioception was assessed by joint position sense, which was evaluated by measuring the error angle when the subjects tried to reproduce the predetermined angle by extension and by flexion. Proprioceptive deficit in the study group was evaluated, compared with age-matched normal subjects. Postoperative recovery and correlation to functional status was analyzed in the study group. The Japanese Orthopedic Association (JOA) scores were used for functional evaluation.

RESULTS

The error angles were significantly higher in the study group than those in the control group before surgery. All patients in the study group finally had improvement of the error angles by a year after surgery. The average of error angles in the study group was improved 2 weeks after surgery; however, no changes were observed later. There was significant correlation between the improvement rate of the error angles 2 weeks after surgery and that of the JOA scores 2 years after surgery. There were 9 patients who had worsened proprioception 2 weeks after surgery either by extension or by flexion, all of whom had poor functional outcome.

CONCLUSIONS

Knee proprioception was impaired in cervical myelopathy and recovered after surgical posterior decompression. Proprioceptive improvement at 2 weeks correlates with the degree of improvement in JOA scores at 2 years after surgery.

Impaired joint proprioception in patients with cervical myelopathy

STUDY DESIGN

Prospective clinical study.

OBJECTIVES

To evaluate impairment of proprioception quantitatively in patients with cervical myelopathy.

SUMMARY OF BACKGROUND DATA

Sensory information regarding proprioception ascends through the posterior columns in the spinal cord. Damage to these columns causes proprioceptive loss in patients with spondylotic myelopathy. Nevertheless, there have been few studies regarding proprioception in patients with myelopathy.

METHODS

The authors evaluated knee proprioception in 54 cervical myelopathy patients and compared results with those of 54 age-matched healthy volunteers. Knee proprioception was assessed by joint position sense, represented by the error angles when patients reproduced predetermined angles of knee flexion.

RESULTS

The average absolute angle error of right and left knee with the predetermined position of 30 degrees of knee flexion was 2.5 +/- 1.8 (mean +/- standard deviation) and 1.8 +/- 1.2 degrees and with the predetermined 60 degrees of flexion, 4.7 +/- 2.8 and 2.8 +/- 1.4 degrees in the myelopathy and control groups, respectively. The average absolute angular errors in the myelopathy group were significantly higher than those in the control group for each predetermined knee position (P < 0.01).

CONCLUSIONS

Proprioceptive ability is impaired in patients with cervical myelopathy. Position sense can be assessed by measuring the angular error when reproducing criterion positions, and the results may reflect the severity of cervical myelopathy. Thus, the present method of measuring proprioception is easy to perform and useful for quantitative assessment of the severity of cervical myelopathy.

The stability of the cemented tibial component of total knee arthroplasty: posterior cruciate-retaining versus posterior-stabilized design

Micromotion of the tibial component in 40 knee arthroplasties for gonarthrosis was studied using Roentgen stereophotogrammetric analysis. The stability of this component was assessed for 2 years' postoperatively. In all arthroplasties, an attempt was made to reconstruct the preoperative posterior slope. Posterior cruciate-retaining (CR) and posterior-stabilized (PS) components showed at 2 years a maximum total point motion of 0.6 +/- 0.4 mm and 0.7 +/- 0.5 mm, respectively. Whereas 92.5% of the implants were determined to be stable, 1 of the CR group and 2 of the PS group displayed migration between the first and the second year of at least 0.2 mm. A negative correlation between subsidence of the tibial component at 2 years of follow-up and the difference between preoperative and postoperative tibial slope was found. Consequently, we suggest that restoring the original posterior slope of the tibial plateau must be a goal of tibial component implantation.

Modification of the posterior cruciate ligament tension following total knee arthroplasty: comparison of the Genesis CR and LCS meniscal bearing prostheses

AIM

A biomechanical study was conducted to determine the in-vitro modification of the posterior cruciate ligament tension following different types of total knee arthroplasty (TKA).

MATERIALS AND METHODS

The Genesis CR (non-mobile tibial inlay, n=9) and LCS meniscal bearing prostheses (mobile meniscal bearings, n=8) were compared with the human cadaveric knee joint. Posterior cruciate ligament (PCL) tension was assessed with implantable force transducers. A six-degree-of-freedom manipulator was used to measure knee kinematics at 10 degrees intervals from 0 degrees to 120 degrees of flexion with [300 Newton (N)] and without load application (0 N). Statistical analysis was performed with the Wilcoxon rank sum test.

RESULTS

Analysis of the PCL tension following TKA using the Genesis CR prosthesis revealed a non-significant (P=0.20) decrease of transducer output with load (300 N) and a non-significant (P=0.73) increase without load (0 N). Concerning the LCS meniscal bearing prosthesis a significant (P=0.01) decrease of transducer output was assessed with load (300 N) whereas a non-significant (P=1.0) modification was seen without load (0 N).

CONCLUSION

The Genesis CR prosthesis allows PCL tension to be close to normal as the knee flexes, which is contradictory to the assumed evidence for a missing restorability of a regular PCL tension after TKA. Our results hence indicate, that the effected tension of the PCL strongly depends on the balance and interaction between design of the implant and the functional role of the retained PCL.

Joint proprioception before and after total knee arthroplasty

To investigate the effects of total knee arthroplasty on joint proprioception, the absolute angular error of the knee in 38 consecutive patients before and after total knee arthroplasty for osteoarthritis and in 23 age-matched control subjects were examined. Varus and valgus laxity of the knee and muscle strengths of the thigh were measured using appropriate instruments. There were no significant differences in absolute angular error before and after total knee arthroplasty, independent of retaining or substituting the posterior cruciate ligament. The absolute angular error of the knee with a normal appearing anterior cruciate ligament was larger than that with a missing anterior cruciate ligament before total knee arthroplasty and decreased significantly after surgery. The absolute angular error correlated with the varus and valgus laxity of the knee, but did not correlate with the strength of thigh muscles after total knee arthroplasty. These results suggest that deficiency of the anterior cruciate ligament may not adversely affect proprioception in severe knee osteoarthritis. In addition, proper ligament balance may partly contribute to better proprioception after total knee arthroplasty.

Manual and manipulation techniques for rheumatic disease

Table 1 summarizes many of the studies cited in this article. Can we specifically answer the question, "Does manipulation effectively treat musculoskeletal disorders and arthritis?" It is apparent that many individuals make decisions to see therapists who use manual techniques for pain relief and improved function even though few third-party payers cover such treatments. If this question could unequivocally be answered in the affirmative, these treatments would likely be reimbursed by the payers. The studies noted in Table 1 show mixed results for several conditions. Each study has its strengths and weaknesses, but the most powerful ones indicate that manual techniques are beneficial for back and neck pain when compared with no treatment or "placebo." Comparative studies against other techniques such as physical therapy, education, or exercise do not show a clear superiority for manual therapy, however. Thus, one would have to conclude that these techniques have usefulness, primarily as adjuncts to a comprehensive treatment program. Particularly, manual techniques are useful for painful conditions as a means to break the pain cycle and increase tolerance of exercise and other educational approaches. Although clinical trials do provide important information, they do not provide information on the mechanism by which the therapy assists in the healing process. Further work is needed to understand the mechanism by which manipulation affects pain and motion. Such research should clarify the discrepancies reported in the clinical trials and provide better designs for future studies.

Proprioception after total knee arthroplasty: a comparison with clinical outcome

We determined proprioception in replaced and unreplaced arthrotic knees by measuring threshold levels for the perception of passive knee motion. In addition, results of these proprioception measurements were compared with the clinical outcomes in patients with a total knee arthroplasty. Threshold detection levels were significantly higher in the replaced than in the unreplaced knees. Moreover, detection-failure rates were significantly higher in the replaced knees as well. In contrast to this diminished movement sense in the replaced knees, clinical examination of these knees showed good or excellent outcome in all cases. A correlation between the clinical outcome and the ability to perceive passive motion in either patient group could not be found. We hypothesize that our findings may be due to the operative removal of intraarticular receptor-rich tissue that is affected by arthrosis. This would not only contribute to marked clinical improvements but also to a significant decrease in proprioception.

Manual and manipulation techniques for rheumatic disease

Manipulation is practiced primarily by chiropractors and osteopaths and is one of the most commonly utilized alternative treatments for rheumatic diseases. Low back pain and neck pain are the most frequently treated disorders, but manipulation is also used to treat a broad range of rheumatic diseases. Manipulation has been shown to decrease joint pain and normalize function. The mechanisms of action, however, are not well understood. Current theories propose an imbalance of muscle activity is a source of pain that manipulation can relieve through reflexive actions. Such muscle imbalances would exacerbate rheumatic and arthritic conditions, suggesting that manipulation may be an important therapy that is appropriate for early conservative care as part of a comprehensive treatment program.