Transcutaneous oxygen tension in the anterior skin of the knee after minimal incision total knee arthroplasty

Comparison of minimally invasive approaches and standard median parapatellar approach for total knee arthroplasty: A systematic review and network meta-analysis of randomized controlled trials

BACKGROUND: Minimally invasive total knee arthroplasty (TKA) has been actively advertised by the orthopedic industry. The purpose of this network meta-analysis was to comprehensively compare the effectiveness of four minimally invasive surgery (MIS) approaches and the medial parapatellar (MPP) approach to improve the American Knee Society Score (KSS) in primary TKA. MATERIALS AND METHODS: Studies were comprehensively searched on PubMed, Embase, Cochrane Library (CENTRAL), Web of Science and Science Direct up to June 2018 with a major focus on the outcome of KSS. Risk of bias was assessed using the Cochrane risk of bias tool. Quality assessment was performed using the GRADE system. Both pair-wise and network meta-analyses are calculated to comprehensively compare the effectiveness of four MIS and TKA approaches. RESULTS: Eleven trials with 1025 knees undergoing TKA were included. Our analysis showed that both MPP and MIS approaches provided improvement in terms of short-term (four-eight weeks) total, objective and functional KSS. The network-meta analysis revealed that MIS approaches showed a trend towards superior KSS improvement over standard MPP approaches. However, statistical advantages were only observed in the mini-MPP group for functional KSS compared to the conventional MPP and quadriceps-sparing (QS) groups. CONCLUSIONS: Evidence shows that MIS TKA approaches are effective alternatives to MPP approaches. However, orthopedic surgeons should be cautiously optimistic about minimally invasive TKA in terms of KSS improvement.

Clinical application of transcutaneous oxygen pressure measurements during exercise

Exertional lower limb pain is a frequent diagnostic issue in elderly patients. Arterial claudication results from the mismatch between the oxygen requirement of, and oxygen delivery to the exercising muscles. Non-invasive vascular investigations (ultrasound imaging, plethysmography or segmental pressure) are used in routine at rest or following exercise, but none can be used during walking or to directly monitor cutaneous oxygen delivery to the limb. Here, we review the methods, tips and traps of the transcutaneous oxygen pressure measurement technique and potential applications. Transcutaneous oxygen pressure measurement is largely used in vascular medicine for patients with critical limb ischemia. It can also detect regional blood flow impairment at the proximal and distal limb simultaneously and bilaterally during exercise. Exercise-oximetry can also analyze systemic oxygen pressure changes on a reference area on the chest, to screen for occult pulmonary disease. As a surface technique, it does not directly measure muscle oxygen content but provides a reliable estimation of regional blood flow impairment. With the use of a recently reported index that is independent of the unknown transcutaneous gradient for oxygen, exercise-oximetry provides some accurate information compared to classical non-invasive vascular investigations to argue for a vascular or non-vascular origin of exertional lower limb pain during exercise. Although a time consuming technique, it is a simple test and it is progressively spreading among referral vascular centers as a useful non-invasive diagnostic tool for patients suspected of arterial claudication.

Regional differences in temperature course after knee arthroplasty

PURPOSE

During wound healing after surgery, physiological inflammation leads to an increase in soft tissue perfusion. This is reflected by a characteristic temperature course in the skin. Although local surgical trauma also influences soft tissue perfusion, no data have been available on the regional temperature distribution after knee arthroplasty to date. This study aims at testing the hypothesis that the greatest regional difference in the temperature course is on the site of the maximum surgical trauma (medially) after knee arthroplasty implantation. This is to our knowledge the first study to present regional differences in the temperature course after TKA which would limit the diagnostic value of thermography.

METHODS

Forty-two subjects who were to receive a surface replacement of the knee joint due to primary varus gonarthrosis were included in the study. In all cases, a medial parapatellar approach was chosen. Patients who underwent lateral release or a release of the lateral ligament structures were excluded. In all patients, a thermographic temperature determination was carried out on the operated knee joint every day up to the seventh post-operative day.

RESULTS

On the medial side, there was no significant change in temperature between day one 34.9° ± 0.2° (34.6-35.3 °C) and seven after surgery. Thereafter, the temperature remained constant here up to the seventh day after the operation. In contrast to this, on the lateral side there was an increase in skin temperature from the second 35.0 ± 0.2 °C (34.7-35.4 °C) to the fifth 34.6° ± 0.2° (34.1-34.9 °C) post-operative day (p = 0.002). Thereafter, the temperature remained constant here up to the seventh day after the operation.

CONCLUSION

This study refutes the hypothesis that the greatest regional difference in the temperature course is on the site of maximum surgical trauma (medially) after knee arthroplasty implantation. It is shown to the contrary that there is the least regional difference in the temperature course on the site of maximum surgical trauma (medially) after total knee arthroplasty implantation. It is on the site of the minimal trauma (laterally) where marked differences in the temperature course appeared. The normal temporary temperature increase typical of physiological wound healing could only be shown at a distance from the site of soft tissue preparation. This may be the result of a local compromise of perfusion. Consequently, the post-operative diagnostic application of thermography remains limited to regions distant from the surgical site. This may prevent misinterpretation of post-operative thermographic measurements for scientific or clinical reasons.

LEVEL OF EVIDENCE

II.

Comparison of Mini-Midvastus and Conventional Total Knee Arthroplasty with Clinical and Radiographic Evaluation: A Prospective Randomized Clinical Trial with 5-Year Follow-up

BACKGROUND

The main objective of this prospective randomized study was to compare the clinical and radiographic outcomes of the mini-midvastus (MMV) approach with the conventional approach for total knee arthroplasty at the 5-year follow-up.

METHODS

Ninety-seven patients (100 knees) with osteoarthritis were assigned to the MMV group or to a group receiving conventional total knee arthroplasty. Intraoperative and postoperative clinical data were collected. At 6 weeks and at 1, 2, and 5 years postoperatively, the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Oxford Knee Score (OKS), the Knee Society Score (KSS), and the Short Form (SF)-12 were completed. Radiographs of the knee were made preoperatively and at 1 day and 1 and 5 years postoperatively. Computed tomography (CT) scans were performed 2 years postoperatively.

RESULTS

In the MMV group, the mean skin incision was 2.5 cm shorter (p < 0.001) and the mean duration of the operation was 6 minutes longer than in the conventional total knee arthroplasty group (p < 0.05). Eight patients in the conventional group had a lateral parapatellar retinacular release compared with 1 in the MMV group; the difference was significant (p = 0.01). Three intraoperative complications, including 2 small lateral femoral condylar fractures and 1 partial patellar tendon laceration, occurred in the MMV group. Seven patients in the MMV group had postoperative blisters; all of them had a relatively large femoral component and 4 of them were large men. The radiographs and CT scans of the prostheses showed no significant differences between the MMV and conventional groups except for the posterior slope of the tibial component. In addition, no significance differences were detected between the groups with respect to the KOOS, OKS, KSS, and SF-12 scores determined at the 6-week and the 1, 2, and 5-year follow-up evaluations.

CONCLUSIONS

In the rehabilitation period and at the short and mid-term follow-up, no relevant clinical and radiographic differences were found between the MMV and the conventional approach for total knee arthroplasty, making the advantage of MMV total knee arthroplasty cosmetic. We discourage the use of the MMV approach in large male patients because of the increased number of intraoperative complications and skin blisters postoperatively.

LEVEL OF EVIDENCE

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

What are the important surgical factors affecting the wound healing after primary total knee arthroplasty?

Background

Wound condition after primary total knee arthroplasty (TKA) is an important issue to avoid any postoperative adverse events. Our purpose was to investigate and to clarify the important surgical factors affecting wound score after TKA.

Methods

A total of 139 knees in 128 patients (mean 73 years) without severe comorbidity were enrolled in the present study. All primary unilateral or bilateral TKAs were done using the same skin incision line, measured resection technique, and wound closure technique using unidirectional barbed suture. In terms of the wound healing, Hollander Wound Evaluation Score (HWES) was assessed on postoperative day 14. We performed multiple regression analysis using stepwise method to identify the factors affecting HWES. Variables considered in the analysis were age, sex, body mass index (kg/m²), HbA1C (%), femorotibial angle (degrees) on plain radiographs, intraoperative patella eversion during the cutting phase of the femur and the tibia in knee flexion, intraoperative anterior translation of the tibia, patella resurfacing, surgical time (min), tourniquet time (min), length of skin incision (cm), postoperative drainage (ml), patellar height on postoperative lateral radiographs, and HWES. HWES was treated as a dependent variable, and others were as independent variables.

Results

The average HWES was 5.0 ± 0.8 point. According to stepwise forward regression test, patella eversion during the cutting phase of the femur and the tibia in knee flexion and anterior translation of the tibia were entered in this model, while other factors were not entered. Standardized partial regression coefficient was as follows: 0.57 in anterior translation of the tibia and 0.38 in patella eversion.

Conclusions

Fortunately, in the present study using the unidirectional barbed suture, major wound healing problem did not occur. As to the surgical technique, intraoperative patella eversion and anterior translation of the tibia should be avoided for quality cosmesis in primary TKA.

Influence of skin incision position on physiological and biochemical changes in tissue after primary total knee replacement - a prospective randomised controlled trial

Background

Influence of skin incision position on physiological and biochemical changes in tissue after primary total knee replacement. A prospective randomised controlled trial.

The blood supply to the skin covering the anterior knee has been shown to arise predominantly from blood vessels on the medial side of the knee. Skin incisions for primary Total Knee Replacement (TKR) positioned medially therefore risk creating a large lateral skin flap that may be poorly perfused. Poorly perfused skin is likely to result in hypoxia at the wound edges and consequently may lead to delayed wound healing and complications.

Methods

We have carried out a randomised controlled trial (n = 20) to compare blood flow on both the medial and lateral sides of two commonly used skin incisions in TKR (midline and paramedian). We have also assessed interstitial biochemistry (glucose, pyruvate and lactate levels) in the presumed at risk lateral skin flap of both incision types.

Results

In both incision types tissue hyper-perfusion occurs post-operatively and is maintained for at least 3 days. We found no significant difference between blood flow between the two incision types on the medial side of the incision at either day 1 (p = 0.885) or day 3 post-op (p = 0.269), or, on the lateral side of the incision (p = 0.885 at day 1, p = 0.532 at day 3). Glucose levels are maintained post-operatively in the at risk lateral flap with only minimal changes. Lactate levels rise post-operatively and remain elevated for at least 24 hours. However, the levels did not reach levels suggestive of critical ischaemia in either incision group and no significant difference was observed between incision types.

Conclusion

We conclude that the use of a paramedian incision results in only minimal biochemical changes, which are unlikely to alter wound healing.

Trial registrations

ISRCTN06592799.