Total Knee Arthroplasty With Lateral Parapatellar Approach Results in Less Early Postoperative Skin Numbness Than Medial Approach, but No Difference at Mid-Term Follow-Up: A Randomized Control Trial

Background

Anterior skin numbness is a common complication after total knee arthroplasty (TKA) that may impact postoperative functional outcomes. This study aimed to compare skin numbness area, functional outcomes, and patient satisfaction between patients undergoing TKA with a medial parapatellar approach (medial group) and a lateral parapatellar approach (lateral group).

Methods

A prospective randomized study included 68 knees undergoing TKA via the medial parapatellar approach (n = 32) and the lateral parapatellar approach (n = 32) through the midline skin incision. Anterior skin numbness was assessed as the primary outcome using Semmes-Weinstein monofilaments at 6 postoperative timepoints (2 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years). Knee range of motion, Knee Injury and Osteoarthritis Outcome Score (KOOS), and patient satisfaction scores were collected. Fifty-nine patients were retrieved at the 2-year final follow-up. Statistical analysis considered repeated outcome measurements with adjusted P-values.

Results

The lateral group had a significantly smaller area of anterior skin numbness at 2 weeks (11.2 vs 20.2 sq.cm.), 6 weeks (8.2 vs 17.2 sq.cm.), and 3 months (7.8 vs 14.4 sq.cm.) postoperatively compared to the medial group. No difference in the area of numbness was found at 6 months, 1 year, and 2 years. Although the lateral group showed significantly higher satisfaction scores (P = .027) and the KOOS symptoms subdomain (P = .018), there were no differences in knee range of motion and other components of KOOS in both groups.

Conclusions

Compared to the medial approach, the lateral parapatellar approach in TKA demonstrates a reduced area of early postoperative skin numbness and expedited 6-month recovery, along with marginally superior patient satisfaction scores. However, both approaches yield comparable outcomes in terms of postoperative knee motion and overall functional outcomes.

The outcome of revision total hip arthroplasty for instability

Aims

Instability is a common indication for revision total hip arthroplasty (THA). However, even after the initial revision, some patients continue to have recurrent dislocation. The aim of this study was to assess the risk for recurrent dislocation after revision THA for instability.

Methods

Between 2009 and 2019, 163 patients underwent revision THA for instability at Stanford University Medical Center. Of these, 33 (20.2%) required re-revision due to recurrent dislocation. Cox proportional hazard models, with death and re-revision surgery for periprosthetic infection as competing events, were used to analyze the risk factors, including the size and alignment of the components. Paired t-tests or Wilcoxon signed-rank tests were used to assess the outcome using the Veterans RAND 12 (VR-12) physical and VR-12 mental scores, the Harris Hip Score (HHS) pain and function, and the Hip disability and Osteoarthritis Outcome score for Joint Replacement (HOOS, JR).

Results

The median follow-up was 3.1 years (interquartile range 2.0 to 5.1). The one-year cumulative incidence of recurrent dislocation after revision was 8.7%, which increased to 18.8% at five years and 31.9% at ten years postoperatively. In multivariable analysis, a high American Society of Anesthesiologists (ASA) grade (hazard ratio (HR) 2.72 (95% confidence interval (CI) 1.13 to 6.60)), BMI between 25 and 30 kg/m2 (HR 4.31 (95% CI 1.52 to 12.27)), the use of specialized liners (HR 5.39 (95% CI 1.97 to 14.79) to 10.55 (95% CI 2.27 to 49.15)), lumbopelvic stiffness (HR 6.03 (95% CI 1.80 to 20.23)), and postoperative abductor weakness (HR 7.48 (95% CI 2.34 to 23.91)) were significant risk factors for recurrent dislocation. Increasing the size of the acetabular component by > 1 mm significantly decreased the risk of dislocation (HR 0.89 (95% CI 0.82 to 0.96)). The VR-12 physical and HHS (pain and function) scores improved significantly at mid term.

Conclusion

Patients requiring revision THA for instability are at risk of recurrent dislocation. Higher ASA grades, being overweight, a previous lumbopelvic fusion, the use of specialized liners, and postoperative abductor weakness are significant risk factors.

An anatomic consideration of the femoral nerve during direct anterior hip approach: A cadaveric study

PURPOSE

This study aimed to investigate the distance and correlation between the anatomy of the anterior side of the hip joint and the femoral nerve.

METHODS

Using ten fresh-frozen cadavers with twenty hip joints. We dissected and marked the femoral nerve in the inguinal area. Employing the direct anterior approach, we identified and marked study points, including the superior and inferior points of the anterior rim of the acetabulum, ¼ point, half point, and ¾ point along an imagined line connecting the formers, the inferomedial and mid aspect of the femoral neck, and the soft spot. Coronal plane measurements gauged the distance between these points and the femoral nerve. The collected data were analyzed to assess the distance and correlation.

RESULTS

In the coronal plane, the median distance between the inferior point of the anterior rim of the acetabulum and the femoral nerve was 0 millimeters (interquartile range [IQR] 0-0). Likewise, the median distance between the mid aspect of the medial side of the femoral neck and the femoral nerve was 0 millimeters (IQR 0-0). Additionally, the mean distance between the soft spot and the femoral nerve was 1.18 cm (SD 0.63).

CONCLUSION

Surgeons approaching the hip joint via the direct anterior approach should be cautious at the inferior point of the anterior rim of the acetabulum and the mid aspect of the femoral neck. The soft spot at the anterior rim of the acetabulum remains safe from direct injury when surgeons use the correct technique during anterior retractor insertion.

Biomechanical analysis of posteromedial tibial plateau fracture fixation in fresh cadaveric bone

This study aims to compare the mechanical strength of three different posterior-based internal fixation methods for posteromedial tibial plateau fractures. The study utilized 12 tibial plateaus harvested from fresh-frozen cadavers, and the posteromedial fracture fragments were created. The bones were then randomly assigned to one of three fixation methods: two posteroanterior lag screws (LS) size 4.0 mm, posterior buttress plate using a 3.5 mm small dynamic compression plate (DCP), or posterior buttress plate using a 3.5 mm T-shaped plate (TP). Biomechanical testing was performed by applying vertical compression force to the center of the posteromedial fracture fragment until the load to failure (displacement ≥ 3 mm) was reached, and displacement of the fragment was measured using a motion sensor. The data exhibited normal distribution, and one-way analysis of variance (ANOVA) was used to determine the load to failure, followed by Fisher post hoc Least-Significant Difference (LSD) to correct for multiple comparisons. The statistical analysis demonstrated significantly higher mean load to failure values in the T-shaped plate group compared to both the small dynamic compression plate group and the lag screw group (p < 0.05). However, after conducting further post hoc analysis, the observed significant differences were solely between the LS and TP groups (p = 0.021). These findings suggest that the T-shaped plate represents the most effective method for internally fixing posteromedial tibial plateau fractures.

Comparison of Dislocation and Outcome Between Piriformis-Sparing and Conventional Posterior Approach After Bipolar Hemiarthroplasty for Femoral Neck Fracture in Patients Over 60 Years

BACKGROUND

Hemiarthroplasty is a treatment option for femoral neck fractures in patients aged more than 60 years and postoperative dislocation after a posterior approach is not uncommon. The piriformis tendon is one of the structures providing posterior hip stability. However, evidence of piriformis-sparing approach in hemiarthroplasty is unclear regarding a reduced dislocation rate.

METHODS

Between January 2017 and December 2019, 321 patients underwent a posterior approach in consecutive cohorts for a hemiarthroplasty for femoral neck fractures with the minimum 24 months follow-up time (24-60 months). There were two cohorts: (1) 129 underwent the conventional posterior (CP) approach and (2) 192 underwent the piriformis-sparing (PS) approach. The differences in dislocation rate, postoperative Harris Hip Society at 1 and 2 years and other surgical complications were compared in both groups.

RESULTS

There were 6 dislocations of 129 (4.7%) underwent the CP approach and 0 dislocation from 192 underwent the PS approach that had posterior hip dislocations (P = .004). In addition, the CP group had a significantly higher mortality rate (14.7% versus 7.3%, P = .031) and lower functional outcomes as assessed by mean Harris Hip Scores at 1 year (73 versus 78, P = .005) and 2 years postoperatively (73 versus 80, P < .001) relative to the PS group.

CONCLUSION

PS hemiarthroplasty was associated with a lower dislocation and mortality rate. Moreover, this approach gained a superior early to the mid-term functional outcome than the conventional posterior approach in elderly femoral neck fractures.

LEVEL OF EVIDENCE

II, prospective cohort study.

Complications, Implant Survivorships, and Functional Outcomes of Conversion Total Knee Arthroplasty With Prior Hardware

BACKGROUND

End-stage knee osteoarthritis with retained periarticular hardware is a frequent scenario. Conversion total knee arthroplasty (TKA) leads to excellent outcomes, but poses unique challenges. The evidence supporting retention versus removal of hardware during TKA is controversial.

METHODS

Patients who underwent TKA with prior hardware between January 2009 and December 2019 were identified. A total of 148 patients underwent TKA with prior hardware. The mean follow-up was 60 months (range, 24-223). Univariate and multivariable analyses were used to study correlations among factors and surgical-related complications, prosthesis failures, and functional outcomes.

RESULTS

The complication rate was 28 of 148 (18.9%). The use of a quadriceps snips in addition to a medial parapatellar arthrotomy was associated with a higher complication (odds ratio: 20.7, P < .05), implant failures (odds ratio: 13.9, P < .05), and lower the Veterans Rand 12 Mental Score (VR-12 MS) (-14.8, P < .05). Hardware removal versus retention and use of single versus multiple incisions were not associated with complications or prosthesis failures. Removal of all hardware was associated with significantly higher (+7.3, P < .05) VR-12 MS compared to retention of all hardware.

CONCLUSIONS

TKA with prior hardware was associated with more complications, implant failures, and lower VR-12 MS when a more constrained construct or quadriceps snip was performed. This probably reflects the level of difficulty of the procedure rather than the surgical approach used. Hardware removal or retention was not associated with complications or implant failures; however, removal rather than retention of all prior hardware is associated with increased general health outcomes.

LEVEL OF EVIDENCE

IV, cohort without control.

The efficacy of intra-articular triamcinolone acetonide 10 mg vs. 40 mg in patients with knee osteoarthritis: a non-inferiority, randomized, controlled, double-blind, multicenter study

BACKGROUND

Intra-articular (IA) corticosteroid injection is recommended in refractory knee osteoarthritis patients. However, 40-mg of triamcinolone IA every 3 months for 2 years reduces cartilage volume as compared to saline IA.

OBJECTIVE

To determine the non-inferiority of 10-mg versus 40-mg of triamcinolone acetonide (TA) for treatment of pain in symptomatic knee osteoarthritis at week 12.

METHODS

This was a double-blind, randomized, controlled trial conducted in 84 symptomatic knee osteoarthritis patients. The 10-mg or 40-mg of TA were 1:1 randomized and injected to the affected knees. The primary outcome was the 12-week difference from baseline in pain VAS, with a pre-specified lower margin for non-inferiority of 10 mm. The measuring instruments used were: Visual analog scale (VAS: 0-10), modified Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), EuroQol Group 5 Dimensions (EQ5D), Knee Injuries and Osteoarthritis Outcome Score (KOOS) questionnaire, chair standing test and 20-m walking time at baseline, at week 4, and week 12 after randomization. Adverse events were recorded.

RESULTS

Baseline characteristics were similar between two groups. The mean differences of pain VAS (95% confidence interval: CI) between the two groups at baseline and week 12 were 0.8 (-0.8, 2.4) with p of 0.002 for non-inferiority. There were no differences in pain reduction and quality of life improvement between 10-mg and 40-mg groups. The mean differences (95%CI) of WOMAC, KOOS pain, EQ5D and KOOS quality of life between baseline and week 12 were 0.4 (-1.1, 1.9). -8.7 (-21.3, 3.9), 1.3(-7.1, 9.6) and 1.8 (-11.5, 15.0), respectively. There were significant improvements in pain and quality of life between baseline and week 12 in both groups.

CONCLUSION

The 10 mg of TA is non-inferior to 40 mg TA in improving pain in patients with symptomatic knee OA. Both 10 mg and 40 mg of TA significantly improved pain and quality of life in patients with symptomatic knee OA.

TRIAL REGISTRATION

TCTR, I TCTR20210224002. Retrospectively registered 24 February 2021, http://www.thaiclinicaltrials.org/show/TCTR20210224002.

Isolated Versus Full Component Revision in Total Knee Arthroplasty for Aseptic Loosening

BACKGROUND

Revision of both femoral and tibial components of a total knee arthroplasty (TKA) for aseptic loosening has favorable outcomes. Revision of only one loose component with retention of others has shorter operative time and lower cost; however, implant survivorship and clinical outcomes of these different operations are unclear.

METHODS

Between January 2009 and December 2019, a consecutive cohort of revision TKA was reviewed. Univariate and multivariable analyses were used to study correlations among factors and surgical related complications, time to prosthesis failure, and functional outcomes (University of California Los Angeles, Knee Society functional, knee osteoarthritis and outcome score for joint replacement, Veterans RAND 12 (VR-12) physical, and VR-12 mental).

RESULTS

A total of 238 patients underwent revision TKA for aseptic loosening. The mean follow-up time was 61 months (range 25 to 152). Ten of the 105 patients (9.5%) who underwent full revision (both femoral and tibial components) and 18 of the 133 (13.5%) who underwent isolated revision had subsequent prosthesis failure [Hazard ratio (HR) 0.67, P = .343]. The factor analysis of type of revision (full or isolated revision) did not demonstrate a significant difference between groups in terms of complications, implant failures, and times to failure. Metallosis was related to early time to failure [Hazard ratio 10.11, P < .001] and iliotibial band release was associated with more complications (Odds ratio 9.87, P = .027). Preoperative symptoms of instability were associated with the worst improvement in University of California Los Angeles score. Higher American Society of Anesthesiologists status and higher Charlson Comorbidity Index were related with worse VR-12 physical (-30.5, P = .008) and knee osteoarthritis and outcome score for joint replacement (-4.2, P = .050) scores, respectively.

CONCLUSION

Isolated and full component revision TKA for aseptic loosening does not differ with respect to prosthesis failures, complications, and clinical results at 5 years. Poor American Society of Anesthesiologists status, increased comorbidities, instability, and a severe bone defect are related to worse functional improvement.

LEVEL OF EVIDENCE

III, cohort with control.

A vibration sensor approach to detect intra-articular needle tip placement in the knee joint: a proof-of-concept study

BACKGROUND

Intra-articular injection in the dry knee joint is technically challenging particularly for the beginners. The aim of this study was to investigate the possible use of the vibration sensor to detect if the needle tip was at the knee intra-articular position by characterizing the frequency component of the vibration signal during empty syringe air injection.

METHODS

Two milliliters of air were injected supero-laterally at extra- and intra-articular positions of a cadaveric knee joint, using needles of size 18, 21 and 24 gauge (G). Ultrasonography was used to confirm the positions of needle tip. A piezoelectric accelerometer was mounted medially on the knee joint to collect the vibration signals which were analyzed to characterize the frequency components of the signals during injections.

RESULTS

The vibration frequency band power in the range of 500-1500 Hz was visually observed to potentially localize the needle tip placement during air injection whether they were at the knee extra-articular or intra-articular positions, as demonstrated by the higher band power (over - 40 dB or dB) for all the needle sizes. The differences of frequency band power between extra- and intra-articular positions were 18.1 dB, 26.4 dB and 39.2 dB for the needle size 18G, 21G and 24G respectively. The largest difference in spectral power was found in the smallest needle diameter (24G).

CONCLUSIONS

A vibration sensor approach was preliminarily proved to distinguish the intra-articular from extra-articular needle placement in the knee joint. This study demonstrated a possible implementation of an alternative electronic device based on this technique to detect the intra-articular knee injection.

Increasing posterior condyle cut for high-flex knee prosthesis may injure popliteus tendon origin: A comparison between real clinical setting and cadaveric study

Background

High-flex total knee prosthesis designs were proposed to improve flexion in total knee replacement (TKA). One of high-flex features is increasing posterior condyle cut which put popliteal tendon in higher risk of injury and may result in gap changes.

Methods

Prevalence of popliteus footprint injuries were compared between conventional and high-flex TKA in real clinical setting. Thirty-six popliteal origin sites from eighteen fresh cadavers were measured distances between the posterior rim of popliteal tendon origin and posterior border of the lateral femoral condyle (distance A) using digital "Vernier caliper". The mean distances were compared to posterior condyle thickness of different prosthesis designs.

Results

The prevalence of posterior popliteus footprint injury was significantly higher in high-flex TKA compared to the conventional design TKA (17.8% vs 3.5%, p =0.005). The mean of distance A on the right knee was 9.59 mm (6.03-12.70) while the mean of distance A on the left knee was 9.13 mm (5.80-11.07). Posterior condyle thickness of the femoral prostheses varies upon their design and size from 7.4 to 10 mm for conventional model and from 8.2 to 12.5 mm for high-flex design. Possibilities of popliteal tendon injury during posterior condyle bone cut was at least 16.7% for conventional model and 27.8% for the high-flex design.

Conclusion

High-flex TKA prosthesis with thicker posterior condyle relates to higher possibility of popliteal tendon origin injury compared to standard one.

Anterior skin numbness after total knee arthroplasty: A prospective comparison study between diabetic and non-diabetic patients

Background

Anterior skin numbness from injury of the infrapatellar branch of saphenous nerve (IPBSN) and/or the anterior-inferior branch of the femoral cutaneous nerve (AIBFN) has been reported after TKA. A recent study has demonstrated no difference in skin numbness between minimally invasive and standard approach TKA. The purpose of our study was to compare the area of skin numbness following TKA in the diabetic and non-diabetic patient.

Material and methods

120 patients (41 type II diabetic and 74 non-diabetic) undergoing TKA were evaluated. Five diabetic patients with preoperative skin numbness were excluded. Area of anterior skin numbness was periodically evaluated with a minimum 2-year follow-up (FU).

Results

Clinically, there was no difference in prevalence of skin numbness (73.2% vs 68.9%, p = 0.36) and warmness (97.6% vs 97.3%, p = 1.00) between diabetics and non-diabetics. Average area of numbness was comparable. However, duration of numbness recovery was significantly longer in diabetics (8.6 vs 5.3 months, p = 0.001). Diabetics had a higher rate of global anterior numbness (48.3% vs 22.9%, p = 0.045). Prevalence of supero-lateral skin numbness (2.6%, n = 3) correlated with the skin incision extended proximally above upper pole of patella at least 4.0 cm.

Conclusion

The duration of numbness recovery following TKA was significantly longer in diabetic patients.