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

Proprioception and Mechanoreceptors in Osteoarthritis: A Systematic Literature Review

PURPOSE

Osteoarthritis (OA) is one of the most common chronic diseases in the world. It is frequently accompanied by high levels of persistent pain, as well as substantial impairments in function and functional capacity. This review aims to systematically analyze the changes in proprioception and related mechanoreceptors in OA patients.

METHODS

Studies from September 2013 to September 2023 were identified by conducting searches on the PubMed, Web of Science, and Scopus electronic databases following the PRISMA statement. One reviewer independently assessed and screened the literature, extracted the data, and graded the studies. The body of evidence underwent an evaluation and grading process using the ROBINS-I tool, which was specifically designed to assess the risk of bias in non-randomized studies of interventions. Results were summarized using descriptive methods.

RESULTS

A search through 37 studies yielded 14 clinical studies that were ultimately included. The primary focus of the studies was on the knee joint, particularly the posterior cruciate ligament (PCL). The studies found that PCL in OA patients had impaired proprioceptive accuracy, possibly due to changes in mechanoreceptors (Ruffini, Pacini, and Golgi Mazzoni corpuscles). This suggests that dysfunctional articular mechanoreceptors, especially in severe cases of OA, may contribute to reduced proprioception. Dynamic stabilometry also identified significant proprioceptive deficits in patients with knee articular cartilage lesions, underscoring the impact of such lesions on knee proprioception.

CONCLUSIONS

Literature data have shown that proprioceptive accuracy may play an important role in OA, particularly in the knee PCL and cartilage. However, the role of proprioception and related mechanoreceptors needs to be further clarified. Future studies focusing on the relationship between proprioception, OA disease, and symptoms, considering age and gender differences, and exploring OA joints other than the knee should be conducted to improve clinical and surgical outcomes in cases where proprioception and mechanoreceptors are impaired in OA patients.

Relationship Between Mechanoreceptors in the Posterior Cruciate Ligament and Patient Age or Osteoarthritis Severity

Background

Mechanoreceptors in the posterior cruciate ligament (PCL) can produce proprioception, which is an important reason why patients choose cruciate-retaining total knee arthroplasty (TKA). The number of mechanoreceptors in the PCL of patients with knee osteoarthritis (OA) is unknown.

Purpose

To provide a theoretical basis for estimating the number of mechanoreceptors in the PCL by evaluating the relationship between this number and patient age or OA severity.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

An overall 28 PCLs from patients with knee OA were collected at the time of TKA and grouped according to patient age (group A, 60-69 years [n = 8]; group B, 70-79 years [n = 12]; group C, ≥80 years [n = 8]) and OA based on Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (group I, ≤80 [n = 8]; group II, 81-120 [n = 10]; group III, >120 [n = 10]). Hematoxylin and eosin and S-100 immunohistochemical staining were performed on the slices near the tibial attachment of the PCL, and the number of mechanoreceptors in each slice was counted. Multifactor analysis of variance was used to evaluate the relationship between the number of mechanoreceptors and patient age or WOMAC score.

Results

The number of mechanoreceptors (mean ± SD) in groups A, B, and C was 24.00 ± 15.19, 30.92 ± 11.41, and 23.38 ± 11.39, respectively, with no significant between-group differences. The number of mechanoreceptors in groups I, II, and III was 43.50 ± 4.99, 25.00 ± 5.27, and 15.20 ± 5.61, with significant differences between groups I and II, groups I and III, and groups II and III (P < .001 for all).

Conclusion

In patients with knee OA, age had no significant effect on mechanoreceptor count, but the number of mechanoreceptors in the PCL decreased significantly with higher (worse) WOMAC score. These findings suggest that in patients of any age with high WOMAC scores, there may be little value as it relates to knee proprioception in performing a PCL-retaining TKA.

Revision Risk for Total Knee Arthroplasty Polyethylene Designs in Patients 65 Years of Age or Older: An Analysis from the American Joint Replacement Registry

BACKGROUND

Polyethylene bearing design may influence the risk of revision after total knee arthroplasty (TKA). Previous investigations from outside of the United States have suggested the potential for an increased risk of all-cause revision and revision for infection with the use of posterior-stabilized bearings. We examine the risk of revision based on the polyethylene bearing design selection for primary TKA.

METHODS

An analysis of the American Joint Replacement Registry (AJRR) data from 2012 to 2019 was performed. We identified all primary TKAs over the study period and linked cases to supplemental U.S. Centers for Medicare & Medicaid Services (CMS) data where available. Patient demographic characteristics, polyethylene characteristics, procedure dates, and cause for revision were recorded. Analysis was performed to compare minimally stabilized implants (cruciate-retaining, anterior-stabilized, or pivot bearing designs) with posterior-stabilized implants. Cumulative incidence function (CIF) curves and Cox proportional hazard ratios (HRs) were created for all-cause revision and revision for infection in each group.

RESULTS

We identified 305,279 cases with reported minimally stabilized or posterior-stabilized implant characteristics. There were 161,486 cases (52.9%) that utilized posterior-stabilized bearings compared with 143,793 cases (47.1%) with minimally stabilized bearings. For minimally stabilized bearings, 1,693 cases (1.18%) had all-cause revision and 334 cases (0.23%) had revision for infection. For posterior-stabilized bearings, 2,406 cases (1.49%) had all-cause revision and 446 cases (0.28%) had revision for infection. The use of posterior-stabilized bearings had HRs of 1.25 (95% confidence interval [CI], 1.2 to 1.3; p < 0.0001) for all-cause revision and 1.18 (95% CI, 1.0 to 1.4; p = 0.02) for revision for infection.

CONCLUSIONS

Similar to investigations from international registries, we found an increased risk of all-cause revision and revision for infection when using posterior-stabilized bearings in TKA in the United States. Surgeons should consider this finding when considering bearing selection for primary TKA.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Knee Scores of Patients with Non-Lateral Compartmental Knee Osteoarthritis Undergoing Mobile, Fixed-Bearing Unicompartmental Knee and Total Knee Arthroplasties: A Randomized Controlled Trial

Objective

To evaluate knee scores and clinical efficacies of patients with non‐lateral unicompartmental knee osteoarthritis (OA) who randomly underwent mobile‐bearing (MB) unicompartmental knee arthroplasty (UKA), fixed‐bearing (FB) UKA, and total knee arthroplasty (TKA).

Methods

From September 2015 to February 2017, a prospective, randomized, parallel, single‐center trial of 180 patients (78 males and 102 females; 63.3 ± 6.9 years) with non‐lateral compartmental knee OA was performed in the first author‐affiliated hospital. The patients were randomly divided into three groups (each group included 60 patients) and received medial cemented Oxford phase 3 MB UKA, medial cemented Link FB UKA, or cemented DePuy Sigma PFC TKA, respectively. A similar perioperative management and fast‐track surgery program was carried out for all patients. The knee scores at 3‐year follow‐up after operation and clinical efficacies of these three groups of patients were recorded, investigated, and compared.

Results

Primarily, compared to the TKA group, the UKA groups (MB UKA and FB UKA) had shorter operative time (median 63.2 < 67.1 min), less bleeding (8.6 < 30.0 mL), earlier resumption of walking without crutches (3.0 < 8.0 days) and walking up and down the stairs (5.0 < 10.0 days) (P < 0.001), higher FJS scores (78.0 > 74.5) (P = 0.007), better results in all knee scores (except VAS and KSS function scores) (P < 0.05), and a larger maximum flexion angle of the knee at the 3‐year follow‐up (123.0° > 96.0°) (P = 0.001). Secondarily, compared to the TKA group, the MB UKA group showed better results in the Western Ontario and McMaster Universities index (WOMAC) stiffness (83.6 > 79.6), WOMAC total (86.3 > 83.2), Oxford knee score (OKS) (20.0 < 23.0), Forgotten Joint Score (FJS) (78.5 > 74.5), and a larger maximum flexion angle of the knee (123.0 > 96.0) (P < 0.05). Moreover, the FB UKA group showed higher Hospital for Special Surgery Knee Score (HSS) (91.0 > 88.5), WOMAC stiffness (84.3 > 79.6), WOMAC function (85.2 > 81.7), WOMAC total scores (87.6 > 83.2), and a larger maximum flexion angle of the knee (119.0° > 96.0°) than the TKA group (P < 0.05). Overall, there was no significant difference in all knee scores and maximum flexion angles of the knee for the MB UKA and FB UKA groups (P > 0.05). There was one case with original bearing dislocation in MB UKA group. One patient with displacement of the femoral component caused by a fall injury, and another patient, who lost his life in a car accident, were involved in the FB UKA group. There was an infection case and an intermuscular vein thrombosis case in TKA group.

Conclusion

UKA showed more advantages than TKA; however, there was no significant difference between the MB UKA and FB UKA groups for treatment of non‐lateral compartmental knee OA.

QUANTIFICATION OF NEURAL ELEMENTS IN POSTERIOR CRUCIATE LIGAMENT: COMPARISON BETWEEN HEALTHY KNEES AND WITH PRIMARY OSTEOARTHROSIS

Objective:

To quantify the neural elements in the posterior cruciate ligament (PCL) in healthy knees and with primary osteoarthrosis (OA).

Methods:

In two groups with OA, one of cadavers and another of individuals, the area of neural elements identified in histological sections of PCL with anti-S100 immunohistochemistry was quantified.

Results:

The overall mean area of the neural elements was 0.96% ± 0.67%, with the value in the cadaver group of 1.02% ± 0.67% and in the OA group of 0.80% ± 0.64%, with a significant statistically difference (p = 0.001). No correlation was observed between neural element quantification and the age of the individuals (p > 0.05). There was no difference in the quantification of neural elements between the sexes in the cadaver group (p = 0.766), but in the OA group there was a statistically significant reduction in males (p = 0.003). Also, in the osteoarthrosis group there was no difference in the quantification of neural elements in the knees with varus or valgus alignment (p = 0.847).

Conclusion:

There was a decrease in neural element quantification in PCL of individuals affected by OA in relation to non-arthritic individuals, with this quantification not related to age or with the axis of the lower limb. However, this quantification is not related to age or the axis of the lower limb.Level of Evidence III, Case control study.

Histopathological Evaluation of Mechanoreceptors in the Metatarsophalangeal Joint Capsule in Hallux Valgus

To date, we could find no study concerning the relationship between mechanoreceptors in the joint capsule of the first metatarsophalangeal joint and hallux valgus deformity. We aimed to investigate the presence of mechanoreceptors in samples obtained from the first metatarsophalangeal joint capsules of patients with hallux valgus deformity to improve our understanding of the clinical and histopathological features of the disease. Samples were taken from the first metatarsophalangeal joint capsules of 13 fresh-frozen cadavers with normal anatomy (controls) and 29 patients undergoing surgery for hallux valgus (cases). For light microscopy, excised specimens were fixed in 10% formaldehyde and processed for routine histopathological investigation. All samples were dehydrated in a series of ethanol, cleared in xylene, and embedded in paraffin. Orientation of collagen fibers was determined on Masson's trichrome-stained sections, and mechanoreceptors were evaluated on S-100-immunostained sections. In the sections stained with Masson's trichrome, the orientation of collagen fibers was regular in the control group. However, coarse and disoriented collagen bundles were observed in the hallux valgus cases (P ≤ .05). S-100 immunostaining was positive in the sections of both the cases and controls. Finally, free nerve endings were more abundant in the samples obtained from the capsules of hallux valgus cases than from the control group (P ≤ .05). An increase in the number of free nerve endings within the capsules of the first metatarsophalangeal joints in feet with hallux valgus deformity might have a role in the development of clinically relevant joint pain and instability.

Mechanoreceptors in Remnant Posterior Cruciate Ligament and Achilles Tendon Allografts After Remnant-Preserving Posterior Cruciate Ligament Reconstruction: Hematoxylin-Eosin and Immunohistochemical Assessments

BACKGROUND

Mechanoreceptor is a subtype of somatosensory receptor. It conveys extracellular stimuli through intracellular signal conduction via mechanically gated ion channel. It conveys not only kinetic stimuli but also pressure, stretching, touch, and even sound wave. Few studies have determined whether mechanoreceptors are present in Achilles tendon allografts used during remnant-preserving posterior cruciate ligament (PCL) reconstruction (PCLR).

PURPOSE/HYPOTHESIS

The purpose was to investigate whether mechanoreceptors are present in remnant tissues of the PCL and allograft tissues after PCLR. It was hypothesized that mechanoreceptors may be present in the remnant PCL tissue of the patients who underwent remnant PCLR technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

Tissue samples were obtained from 14 participants who had undergone PCLR by means of Achilles tendon allografts (PCLR group) and from 4 healthy controls (control group). Among the PCLR group, 12 patients had undergone a remnant PCLR technique and the remaining 2 patients had undergone a nonremnant PCLR technique. In the PCLR group, we obtained samples during second-look arthroscopy or total knee arthroplasty after PCLR. In the control group, 4 biopsy specimens of normal PCL tissues were obtained from patients who had undergone other arthroscopic procedures. To check the presence of mechanoreceptors, immunohistochemical studies were performed on all biopsy specimens to identify neuronal and neurocytic markers by using monoclonal antibodies against glial fibrillary acidic protein, neuron-specific enolase, neurofilament, and S-100 protein. Only 1 of these markers needed to be positive to prove the presence of mechanoreceptors.

RESULTS

Neural tissue analogs, confirmed to be mechanoreceptors with monoclonal antibodies by the Ultraview DAB detection kit, were found in all specimens obtained from the control group. Mechanoreceptors were not found in the allograft specimens. However, remnant PCL tissues were found to have mechanoreceptors in 11 of 12 samples (91.7%).

CONCLUSION

The results demonstrate that Achilles tendon allografts lack mechanoreceptors. This study can be used as histological evidence to support the advantage of remnant-preserving techniques for PCLR because they preserve proprioception.

CLINICAL RELEVANCE

To preserve proprioception, which leads to better functional outcome, using the remnant technique is a better procedure for PCL reconstruction.

Intact, pie-crusting and repairing the posterior cruciate ligament in posterior cruciate ligament-retaining total knee arthroplasty: A 5-year follow-up

BACKGROUND

The posterior cruciate ligament (PCL) is important for cruciate-retaining (CR) total knee arthroplasty (TKA). Whether the entire PCL should be retained during CR-TKA is controversial.

AIM

To evaluate the clinical outcomes of PCL preservation in CR-TKA and the methods used to deal with the PCL during surgery.

METHODS

A retrospective review of patients with osteoarthritis undergoing primary CR-TKA (176 patients, 205 knees) in our institution between March 2012 and March 2014 was performed. A PCL protector was used to preserve the intact PCL bone block. The status of the PCL was recorded during surgery. Intact PCL preserved, pie-crusting and repairing were used to balance the tension of the PCL. Range of motion (ROM) and the Knee Society Clinical Rating system (KSS) were evaluated preoperatively and at the endpoint of follow-up.

RESULTS

The mean ROM of the knee was 103.2 ± 17.2°, KSS clinical score was 47.6 ± 9.5 and KSS functional score was 46.3 ± 11.9 before surgery. The mean ROM of the knee was 117.5 ± 9.7°, KSS clinical score was 89.2 ± 3.6 and KSS functional score was 84.6 ± 9.8 at 5 years follow-up. ROM, KSS clinical scores and KSS functional scores were significantly improved after surgery (P < 0.01). Thirty-two (23.7%) TKAs involved PCL pie-crusting and 18 (13.3%) involved PCL repair. Eighty-five (63.0%) TKAs applied standard operating procedures and preserved intact PCL. At 5 years follow-up, in the intact PCL group, the mean ROM of the knee was 118.0 ± 8.3°, KSS clinical score was 89.1 ± 3.7 and KSS functional score was 84.9 ± 9.6. In the PCL pie-crusting group, mean ROM of the knee was 114.0 ± 13.5°, KSS clinical score was 88.8 ± 3.4 and KSS functional score was 83.8 ± 10.5. In the PCL repair group, mean ROM of the knee was 120.3 ± 7.0°, KSS clinical score was 89.0 ± 3.6 and KSS functional score was 89.4 ± 4.5. There were no significant differences in ROM, KSS clinical scores and KSS functional scores among the three groups (P > 0.05).

CONCLUSION

The clinical outcomes of preserving the PCL in CR-TKA are encouraging. Pie-crusting and PCL repair do not affect the function. The PCL protector effectively protected the PCL bone block.

Posterior-stabilized versus cruciate-retained implants for total knee arthroplasty: a meta-analysis of clinical trials

AIM

A meta-analysis comparing the outcomes of patients undergoing cruciate retaining (CR) versus posterior stabilized (PS) in primary total knee arthroplasty was performed. The outcomes of interest were the Knee Society Rating System, clinical (KSCS) and functional (KSFS) subscales, joint range of motion (ROM), surgical duration and further complications (anterior knee pain, instability and revision rate).

MATERIALS AND METHODS

The search was conducted in July 2018, accessing the following databases: Cochrane Systematic Reviews, Scopus, PubMed, EMBASE, CINAHL, AMED and Google Scholar. We included only clinical trials level of evidence I and II. During the statistical analysis, we excluded all the studies that affect negatively the I² test, in order to achieve more reliable results. For the methodological quality assessment we referred to the PEDro score. The risk of publication's bias was evaluated by the funnel plots across all the comparisons.

RESULTS

The PEDro score reported a good methodological quality assessment. The funnel plot detected a very low risk of publication's bias. We included in this study 36 articles, counting a total of 4052 patients and 4884 procedures. The mean follow-up term for both groups was 3.39 years. The ROM resulted in an overall estimate effect of 2.18° in favor of the PS group. The overall WOMAC showed a result in favor of the PS group. The overall estimate effect of the KSCS was 0.02% higher in the CR group. The KSFS showed an overall estimate effect of 2.09% in favor of the PS group. Concerning the surgical duration, the estimate effect resulted in 6.87 min shorter in the CR group. No differences were reported across the two groups regarding anterior knee pain, knee joint instability or revision rate.

CONCLUSION

Both the prosthetic implants provided to be a safety and feasible solution to treat end-stage knee joint degeneration. The PS implants reported improvements in the knee range of motion and a prolongation of the surgical time. No clinically relevant dissimilarities concerning the analyzed scores were evidenced. No statistically significant relevant differences in complications were detected.

Unicompartmental versus total knee arthroplasty for knee osteoarthritis

PURPOSE

In the last couple of years, a significant amount of studies comparing the UKA and TKA for unicompartmental knee osteoarthritis have been published. However, there is a lack of recent meta-analysis comparing the two implants. Since the number of performed UKAs is currently increasing and the indications are obsolete, it becomes important to update current evidences and outcomes. With these premises, a meta-analysis of clinical trials comparing UKA versus TKA was conducted.

METHODS

In October 2018, the following databases were accessed: Cochrane Systematic Reviews, Scopus, PubMed and Google Scholar. According to the Oxford Center of Evidence-based Medicine, level of evidence articles I to III were included. Only studies reporting quantitative data concerning the outcomes of interest were included. For the statistical analysis and the methodological quality assessment, we referred to the Review Manager Software 5.3. Dichotomous data were analyzed through the Mantel-Haenszel statistical method with the odd ratio effect measure. For continuous data, the inverse variance statistical method was used with the mean difference effect measure. A confidence interval of 95% was considered for analysis. To evaluate study heterogeneity, both Chi-square and Higgins tests were performed. Values of P < 0.05 were considered statistically significant.

RESULTS

The overall methodological quality assessment was moderate. The risk of publication's bias was moderate. We enrolled in this study a total of 13,789 patients. The mean follow-up was 42.69 months. The UKA evidenced increased risk of revision's surgeries (OR 2.16, P > 0.0001). All the other scores of interest were in favor of the UKA: Oxford Knee Score, KSS Clinical, WOMAC overall and related subscales. The UKA also reported better functional outcomes: KSS Function, longer walking distance, improvement of the joint flexion and ROM. Moreover, in the UKA group have been reported a shorter length of stay, reduced estimated total blood loss and shorter surgical duration.

CONCLUSION

The main findings of this meta-analysis are that UKA reported a reduced survivorship but better clinical and functional performances compared to TKA. Furthermore, shorter surgical duration, lower total estimated blood loss and quicker hospitalization length were observed in the UKA cohort.

Histopathological analysis of the posterior cruciate ligament in primary osteoarthritis

BACKGROUND

According to some authors, the indication of an arthroplasty maintaining the posterior cruciate ligament (PCL) demands adequate structural preservation and proprioceptive function of this ligament. The nervous fibers contained in the synovial neurovascular bundle (NVB) around the PCL are involved in proprioception. A study evaluating the grade of PCL and NVB degeneration by using clinical, radiological, and perioperative parameters in knee arthritis patients, in theory, could help surgeons in the decision of preserving or not preserving the PCL in a particular patient.

QUESTIONS

(1) Can the degree of the PCL collagen fibers degeneration be predicted by clinical, radiographic, and perioperative parameters in knee arthritis patients? (2) Is the NVB histological degeneration status predictable using clinical, radiographic, and perioperative parameters in the same subset of patients? (3) Is there a correlation between the degree of the PCL collagen fibers degeneration and NVB status in knee arthritis patients?

METHODS

Eighty-nine PCLs (85 patients) obtained from total knee replacement surgery were studied. The histologic degeneration of PCL collagen fibers and the NVB status (preserved, degenerated, not detected) were evaluated. These histological degeneration patterns were correlated with clinical and radiographic parameters and with anterior cruciate ligament (ACL) status.

RESULTS

A small prevalence of preserved NVB was related to Grades IV and V of Ahlbäck's classification, ACL absence, and severe PCL degeneration. The clinical and radiological parameters studied were not able to predict the grade of histological degeneration of the PCL.

CONCLUSIONS

Ahlbäck's classification and ACL status provided useful information about NVB integrity.

LEVEL OF EVIDENCE

Basic Science Level IV.

Lower numbers of mechanoreceptors in the posterior cruciate ligament and anterior capsule of the osteoarthritic knees

PURPOSE

Impaired proprioception accuracy of the knee has been proposed as a local factor in the onset and progression of knee osteoarthritis. Patients with decreased numbers of mechanoreceptors could be more likely to develop arthrosis due to a loss in proprioception of the joint. We aimed to identify and quantify the mechanoreceptors of the posterior cruciate ligament (PCL), the anterior capsule (AC) and the medial meniscocapsular junction (MCJ) in knee arthrosis.

METHODS

PCLs, ACs and MCJs were harvested from 30 patients with Kellgren and Lawrence grades 3 and 4 osteoarthritis (OA), and ten knees taken from five cadavers without OA were used as a control group. PCL degeneration was evaluated with haematoxylin & eosin, and the types and numbers of mechanoreceptors were evaluated using S100 immunostaining.

RESULTS

The patient ages in the OA and control groups (n.s.) did not differ. PCL degeneration was more severe in the gonarthrosis group than in the control group (p = 0.04). The numbers of Golgi corpuscles, Ruffini corpuscles, free nerve endings, total nerve endings and small vessels of the PCL were low in the OA group, as were the numbers of Golgi corpuscles, free nerve endings and total nerve endings of the AC. No significant correlation was found regarding the mechanoreceptors of the MCJ between the two groups.

CONCLUSION

The numbers of mechanoreceptors in patients with OA were low in the PCLs and ACs. A loss in proprioception could be a local risk factor in OA. The proprioceptive impact of preserving PCL while performing total knee arthroplasty may not be exaggerated as its thought.

LEVEL OF EVIDENCE

Prognostic study, Level I.

Intraoperative factors affecting conversion from cruciate retaining to cruciate substituting in total knee arthroplasty

PURPOSE

The purpose of this study was to analyse the factors affecting the conversion from posterior cruciate ligament (PCL)-retaining (CR) to PCL-substituting (PS) prostheses during total knee arthroplasty (TKA).

METHODS

A total of 920 TKAs, which had been preoperatively planned to undergo implantation of CR-type prostheses, were reviewed retrospectively. Of these, 83 knees (9.0 %) were converted intraoperatively to PS prostheses. The clinical and radiological factors of the non-converted (CR) and converted (PS) groups were compared. Clinically, age, gender, body mass index, angle of flexion contracture, size of the femoral component, and thickness of the polyethylene insert were compared between the CR and PS groups. Radiologically, the severity of the varus deformity and the posterior tibial slope angle (PSA) were compared between the CR and PS groups.

RESULTS

No significant differences in age, gender, body mass index, range of motion, thickness of the polyethylene insert, or severity of varus deformity were identified. The average preoperative angle of flexion contracture was 5.9° ± 7.4° in the CR group and 8.1° ± 9.1° in the PS group (p = 0.002). The average preoperative PSA was 9.6° ± 4.0° in the CR group and 11.0° ± 5.0° in the PS group (p = 0.018). The conversion rates to a PS-type femoral component of size C, D, and E were 13.1, 7.0, and 6.3 %, respectively (p = 0.004).

CONCLUSION

The conversion rate from CR- to PS-type prostheses was high in patients with severe flexion contracture, steep posterior slope, and a small femoral component size. These factors should be carefully considered for appropriate selection of prosthesis type.

LEVEL OF EVIDENCE

IV.

Proprioception and Knee Arthroplasty: A Literature Review

Proprioceptive mechanoreceptors provide neural feedback for position in space and are critical for three-dimensional interaction. Proprioception is decreased with osteoarthritis of the knees, which leads to increased risk of falling. As the prevalence of osteoarthritis increases so does the need for total knee arthroplasty (TKA), and knowing the effect of TKA on proprioception is essential. This article reviews the literature regarding proprioception and its relationship to balance, aging, osteoarthritis, and the effect of TKA on proprioception. Knee arthroplasty involving retention of the cruciate ligaments is also reviewed, as well the evidence of proprioception in the posterior cruciate ligament after TKA.

Retrospective comparative study shows no significant difference in postural stability between cruciate-retaining (CR) and cruciate-substituting (PS) total knee implant systems

PURPOSE

Modified postural stability after retaining the posterior cruciate ligament (PCL) in total knee arthroplasty is still discussed controversially. The objective of this study was to evaluate whether a PCL-retaining implant design should be preferred over a PCL-substituting implant design regarding postural stability in one-leg stance and clinical outcome.

METHODS

Forty patients underwent total knee arthroplasty, 20 of them with a cruciate-retaining (CR) and 20 of them with a cruciate-substituting (PS) implant system. Postural stability was analysed 6 months postoperatively in one-leg stance using the Biodex Balance System. In addition, the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Knee Society Score were completed.

RESULTS

This study shows that there is no significant difference in postural stability between CR and PS) implant systems with PS implants showing better results in WOMAC score.

CONCLUSIONS

In case it is necessary to use a PS implant, no negative influence on postural stability is to be expected compared to a CR implant.

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.

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.

Proprioception and clinical results of anterolateral single-bundle posterior cruciate ligament reconstruction with remnant preservation

Purpose

To evaluate the clinical and radiological results and proprioception following anterolateral single-bundle posterior cruciate ligament (PCL) reconstruction with remnant preservation for PCL injury.

Materials and Methods

Twenty patients with an isolated PCL injury (16 males and 4 females) were included in this study. The mean follow-up period was 61 months (≥24 months) and the mean age of the patients was 36 years. Knee joint instability was evaluated using posterior drawer stress radiography. Knee function, level of activities, and individual satisfaction were assessed using the Lysholm knee score, Tegner activity score, and 2000 International Knee Documentation Committee (IKDC) score. Knee proprioception was assessed using an isokinetic machine.

Results

The mean ligament laxity assessed using the posterior drawer stress radiography was improved from 10.8-3.2 mm. The mean Lysholm knee score was improved from 70.0-88.9 points, and the mean Tegner activity score was improved from 2.7-6.2 points. Individual satisfaction assessed using the IKDC score was improved from 62.7-85.4 points (p<0.05). Knee proprioception was not significantly different between the treated and the uninjured knees.

Conclusions

Single-bundle PCL reconstruction with remnant preservation for PCL injury exhibited satisfactory outcomes regarding functional outcome, joint stability, and proprioception.

The role of muscle activation in cruciate disease

Traditional investigations into the etiopathogenesis of canine cranial cruciate ligament (CCL) disease have focused primarily on the biological and mechanical insults to the CCL as a passive stabilizing structure of the stifle. However, with recent collaboration between veterinarians and physical therapists, an increased focus on the role of muscle activity and aberrant motor control mechanisms associated with anterior cruciate ligament (ACL) injuries and rehabilitation in people has been transferred and applied to dogs with CCL disease. Motor control mechanisms in both intact and cruciate-deficient human knees may have direct translation to canine patients, because the sensory and motor components are similar, despite moderate anatomic and biomechanical differences. Components of motor control, such as muscle recruitment and the coordination and amplitudes of activation are strongly influenced by afferent proprioceptive signaling from peri- and intra-articular structures, including the cruciate ligaments. In people, alterations in the timing or amplitude of muscle contractions contribute to uncoordinated movement, which can play a critical role in ACL injury, joint instability and the progression of osteoarthritis (OA). A better understanding of motor control mechanisms as they relate to canine CCL disease is vitally important in identifying modifiable risk factors and applying preventative measures, for development of improved surgical and rehabilitative treatment strategies. The purpose of this review article is to analyze the influence of altered motor control, specifically pelvic limb muscle activation, in dogs with CCL disease as evidenced by mechanisms of ACL injury and rehabilitation in people.