Standard Medial Parapatellar Approach Research Articles

The Conversion of Unicompartmental Knee Arthroplasty to Total Knee Arthroplasty with Non-CT-Based Robotic Assistance: A Novel Surgical Technique and Case Series.

Robotic-assisted devices help provide precise component positioning in conversion of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA). A few studies offer surgical techniques for computed tomography (CT) based robotic-assisted conversion of UKA to TKA; however, no studies to date detail this procedure utilizing a non-CT-based robotic-assisted device. This article introduces a novel technique employing a non-CT-based robotic-assisted device (ROSA Knee System, Zimmer Biomet, Warsaw, IN) for converting UKA to TKA with a focus on its efficacy in gap balancing. We present three patients (ages 46-66 years) who were evaluated for conversion of UKA to TKA for aseptic loosening, stress fracture, and progressive osteoarthritis. Each patient underwent robotic-assisted conversion to TKA. Postoperative assessments at 6 months revealed improved pain, function, and radiographic stability. Preoperative planning included biplanar long leg radiographs to determine the anatomic and mechanical axis of the leg. After arthrotomy with a standard medial parapatellar approach, infrared reflectors were pinned into the femur and tibia, followed by topographical mapping of the knee with the UKA in situ. The intraoperative software was utilized to evaluate flexion and extension balancing and plan bony resections. Then, the robotic arm guided placement of the femoral and tibial guide pins and the UKA components were removed. After bony resection of the distal femur and proximal tibia, the intraoperative software was used to reassess the extension gap, and plan posterior condylar resection to have the flexion gap match the extension gap. The use of a non-CT-based robotic-assisted device in conversion of UKA to TKA is a novel technique and a good option for surgeons familiar with robotic-assisted arthroplasty, resulting in excellent outcomes at 6 months.

Primary total knee arthroplasty after extensor mechanism reconstruction with structural allograft (case report)

Introduction. Total knee arthroplasty (TKA) in patients with the extensor mechanism insufficiency is traditionally considered as a complex case. Purpose. To demonstrate the specific features of primary TKA in a patient with a history of the extensor mechanism reconstruction using a structural allograft. Case description. A 32-years-old male was admitted to the hospital due to severe pain and decreased range of motion of the left knee 6 month ago. In 2014, due to a road traffic accident, he experienced an open comminuted fracture of the left patella, complicated by infection. During debridement, the partial patellectomy was performed followed by elimination of surgical site infection. One year after the injury, due to significant extension lag and knee instability during walking, an extensor mechanism reconstruction was performed using a structural allograft including the quadriceps tendon-patella-patellar ligament-tibial tubercle. The screws that were fixing the allograft in the tibial crest were removed one year after the reconstruction. The patient resumed an active lifestyle and practiced martial arts. In 2023, he began experiencing increasing pain, limited range of motion (0°–20°–110°), varus deformity (8°), and extensor lag of 20°. Oxford Knee Score (OKS) was 29 points. Due to the low efficacy of conservative treatment TKA was performed in February 2024. Results. After performing standard medial parapatellar approach, the fusion both of the tendon and bone parts of the structural allograft to the surrounding tissues was confirmed. Surprisingly, disintegration of the distal third of the anterior surface of the patella from the retinaculum was identified. To preserve the integrity of the extensor mechanism, the refixation of the patella to the retinaculum was performed with two anchors and non-absorbable sutures. At the 6-month follow-up, the patient reported no pain, full range of motion and walked without additional support or distance limitations. The OKS was 42 points but extensor lag of 5° persisted. Conclusion. After transplantation of structural allograft of the extensor mechanism, the fusion with the native tissues occurs only in the zones of proximal and distal fixation. Despite the reliable long-term mechanical properties, the whole graft did not go through complete revascularization by host tissue and full remodeling. Therefore, during subsequent surgical interventions, including TKA, it is necessary to be technically prepared for augmentation of the extensor mechanism or its secondary reconstruction

Incidence of soft tissue releases in robotic assisted cementless TKA with mechanical alignment and flexion gap balancing

BackgroundTo ensure the success of total knee arthroplasty (TKA), precise bone cuts and a well-balanced soft tissue envelope are crucial. Soft tissue release may be necessary, subject to various factors. Therefore, documenting the type, frequency, and necessity of soft tissue releases can establish a benchmark for comparing different alignment techniques and philosophies and evaluating their outcomes. The purpose of this study was to demonstrate that robotic-assisted knee surgery requires minimal soft tissue release.MethodsWe prospectively documented and retrospectively reviewed the soft tissue releases employed in securing ligament balance in the first 175 patients who received robotic-assisted TKAs at Nepean Hospital. ROSA was utilized in all surgeries with the aim of restoring mechanical coronal alignment, with a flexion gap balancing technique. Surgeries were performed between December 2019 to August 2021 by a single surgeon who used a standard medial parapatellar approach without a tourniquet, and the cementless persona prosthesis. All patients were followed up for a minimum of 6 months post-surgery. Soft tissue releases included any form of medial release for varus knee, posterolateral release for valgus knee and PCL fenestration or sacrifice.ResultsThere were 131 female and 44 male patients, aged between 48 to 89 years (average 60 years). The preoperative HKA ranged from 22 degrees varus to 28 degrees valgus, with 71% of patients presenting with a varus deformity. For the whole group, the no need for soft tissue release was documented in 123 patients (70.3%), small fenestrated releases of PCL in 27 (15.4%), sacrifice of PCL in 8 (4.5%), medial releases in 4 (2.3%) and posterolateral releases in 13 (7.4%). In 29.7% of patients in whom a soft tissue release was necessary for balance, over half were/received minor fenestrations of the PCL. Outcomes to date included no revisions or impending revisions, 2 MUAs (1%), and Oxford knee scores averaged 40 at 6 months.ConclusionWe concluded that Robot technology enhanced the precision of bone cuts and allowed for titration of required soft tissue releases to achieve optimal balance.

Case Report on Painful Patellar Crepitation Following a Knee Replacement with Preserved Patella

Patellar clunk crepitation is a well-known complication following knee replacement surgery and is associated with posterior stabilized knee replacement surgery and surgical technique. Currently, patellar clunk or crepitation management following knee replacement surgery with preserved patella remains unclear. The purpose of this case report is to discuss whether patellar clunk or crepitation management should include debridement with patellar resurfacing or debridement alone. This case describes a patellar crepitation after knee replacement surgery with the preserved patella. The surgery went uneventfully using the standard medial parapatellar approach. However, the patient was still unsatisfied with the chronic left knee pain (>3 months) and crepitation that developed following the surgery, and the patient was diagnosed with patellar clunk and crepitation (PCC). A patellar resurfacing procedure was performed with a satisfactory clinical outcome. Replicating the original joint line level and placing the tibial component posteriorly play a pivotal role in preventing PCC. Debridement and patellar resurfacing procedures are recommended in this type of case to overcome the valgus knee alignment and the placement of the tibial component.

Efficacy of Periarticular Local Infiltrative Analgesic Injection on Postoperative Pain Control and Functional Outcome in Sequential Bilateral Total Knee Replacement: A Prospective Controlled Trial in 120 Consecutive Patients.

One of the drawbacks of total knee replacements (TKR) is the early postoperative pain, which affects patient satisfaction and increases the duration of rehabilitation. The present study analyzes the potency of local infiltrative analgesia and its effect on rehabilitation in bilateral sequential TKRs. The present prospective observational study was conducted on 120 patients undergoing bilateral sequential TKR performed by a single surgeon using an anterior midline incision with a standard medial parapatellar approach. At the end of the surgery, a periarticular cocktail injection was administered to one knee, whereas the other knee served as the control. Postoperatively, patients were assessed for the pain level in each knee based on the visual analog scale (VAS) score and improvement in the range of motion (ROM). Intergroup and intragroup analyses were performed using the unpaired t test and analysis of variance, respectively. A p value of < 0.05 was considered significant. Of the 120 patients, 58% were women and 42% were men with a mean age of 62.14 ± 8.58years. The postoperative mean VAS score was significantly lower in the test knee group than in the control knee group (p < 0.05). The postoperative mean ROM was more in the test group as compared to the control group on days 3 and 7 (p < 0.05), whereas it was comparable on day 14 (p > 0.05). Periarticular injection of a drug combination in patients managed with bilateral TKRs that are done simultaneously reduces the early postoperative pain and improves rehabilitation during the first week after surgery.

Lateral or Medial Parapatellar Surgical Approach to the Valgus Osteoarthritic Knee? A Retrospective Single-Center Study.

Aims: Total knee arthroplasty in patients with fixed valgus deformity is a demanding procedure. The aim of this study was to compare the clinical results of using the lateral approach [LA] versus the medial approach [MA] in the treatment of fixed valgus knee deformities. Methods: This single-center study compared the results of 143 consecutive patients with fixed valgus deformity (mean 21.55° valgus, mean age 68.2 years) undergoing LA Total Knee Arthroplasty [TKA] to 50 patients (mean 16.58° valgus, mean age 67.2 years) undergoing MA TKA. The mean follow-up period was 5.1 years (2–10 years). Data was collected from operative notes, routine postoperative visits, and radiological findings. Apart from a radiological evaluation, patients were clinically assessed both pre- and postoperatively using the Knee Society Score [KSS]. Descriptive statistics together with the Kolmogorov-Smirnov test, the Student’s t-test for independent samples, and the Mann-Whitney U test were used. The level of significance in this study was α = 0.05. Results: In the LA group, the KSS Knee was significantly higher than in the MA group [85.31 vs. 77.42, respectively, p-value < 0.001]. The difference was also in the KSS total but with no statistical significance [155.17 vs. 149.22, p-value 0.087]. The surgery time in the LA group was shorter than in the MA group [81 vs. 91 min, respectively, p-value—0.002]. The complication rate after surgery was higher in the MA group than in the LA group (14% vs. 9%, respectively). Conclusions: The lateral approach is a good alternative to the standard medial parapatellar approach in the treatment of fixed valgus knee deformities. A higher postoperative KSS Knee, shorter surgery time, and similar complication rate make the lateral approach a valuable option for treating patients with osteoarthritis and fixed valgus knee deformity.

Comparison of subvastus and medial parapatellar approaches in primary total knee arthroplasty in term of clinical outcome

Background &amp; objectives: The purpose of this study was to determine differences in clinical outcome between subvastus and medial parapatellar approach in primary total knee arthroplasty. Methods: This is a prospective randomized study; we compared the clinical results of primary total knee arthroplasty using Subvastus and medial Parapatellar approaches in 34 patients. The standard medial Parapatellar approach used in 19 patients and Subvastus approach used in 15 patients. Clinical outcome assessed using knee society score, time to return quadriceps function and visual analogue scale for pain. Results: The mean follow-up time was 3 months. Pain improved significantly overtime in both groups. However, when comparing groups together, patients in subvastus group had better numerical visual analogue scale score at 3rd day postoperatively, nevertheless, no significant differences found at other follow up times (8.11, 6.05, 4.26, 2.32, 1.47 for medial parapatellar group and 8.20, 4.47, 4.0, 1.67, 1.07 for subvastus group at preoperative, 3rd day, 2, 6 and 12 weeks postoperative respectively for both groups). Subvastus group had earlier return of quadriceps function by 1.9 days which was significant statistically. Knee society score improved significantly overtime without any significant differences when comparing both groups together at any time of the follow up periods (, 66.42, 105.21, 137.63, 155.53 for medial parapatellar group and, 62.53, 107.53, 137.6, 155.81 for subvastus group at preoperative, 2, 6 and 12 weeks postoperative respectively for both groups). Conclusions: Subvastus approach allowed earlier return of quadriceps function and less pain in the early postoperative day. In term of physical and functional outcome, none of two surgical approaches showed advantage over the other

Mapping the Saphenous Nerve from Surgical Landmarks: An Anatomic Guide for Adductor Canal Blocks

Introduction &amp; ObjectiveAn adductor canal block (ACB) targets the saphenous nerve and provides significant pain control following total knee arthroplasties (TKA). Traditionally, the ACB is performed by an anesthesiologist as a pre‐operative procedure where the saphenous nerve is located via ultrasound. However, recent publications conclude orthopedic surgeons can feasibly and safely perform the block peri‐operatively. Researchers demonstrated that the saphenous nerve can be continually targeted from landmarks palpated during TKAs. While current literature supports consistent targeting of the saphenous nerve from palpated landmarks, the descriptive data mapping where the saphenous nerve travels in respect to those landmarks is limited. In this study we will attempt to determine if a consistent measurement exists between the surgically relevant adductor tubercle and the saphenous nerve as it exists within the adductor canal.Materials &amp; MethodsEighteen (n=18) formalin‐embalmed cadavers from Kansas City University’s Gift Donor Program were examined. This inquiry yielded 34 (n=34) lower extremities for investigation. Dissections followed a standard medial parapatellar approach to identify the adductor tubercle. We identified and traced the saphenous nerve through an incision running from the anterior superior iliac spine to the tibial tuberosity. Pinning of the saphenous nerve occurred from the apex of the femoral triangle to its exit of the vasoadductor membrane. The pinned leg was photographed with a scale marker and the image uploaded for analysis in ImageJ. Distances from landmarks to the nerve were calculated in cm based on the center of each pin. The calculated measurements were transferred to GNU Octave to create a contour map. After dissection, the femur was disarticulated from the acetabular and knee joint and measured using an osteometric board. This measurement provided a better understanding of how the distances varied based on height.ResultsThe average distance from the adductor tubercle to where the saphenous nerve exits the vasoadductor membrane was 9.58 cm (σ= 2.40 cm). The distance from the adductor tubercle to the apex of the femoral triangle is 24.32 cm (σ= 3.83 cm). Using these distances, we created a contour map to visualize the variation in measures.ConclusionThis study demonstrates the spatial relationship between the adductor tubercle and the saphenous nerve and illustrates the most common distance the saphenous nerve is found from surgical landmarks. With this information, surgeons know where to target the saphenous nerve when performing a peri‐operative ACB.Significance/ImplicationsSurgeon lead adductor canal blocks provide healthcare teams greater flexibility in treatment where anesthesiologists and technological resources may be limited. This study equips orthopedic surgeons with more descriptive knowledge about the spatial relationship between the saphenous nerve and the surgically relevant adductor tubercle in order to carry out ACB. Future work should repeat our methods to increase sample size to ensure the data better represents the population. Additional studies should include fresh frozen specimens to address the limitations that arise with stiff, formalin embalmed cadavers.

Is the femoral component flexion affected by the sagittal femoral shaft bowing in conventional intramedullary guided TKA?

BackgroundThe aim of the present study was to investigate the influence of sagittal femoral bowing on sagittal femoral component alignment, and whether there was correlation between sagittal femoral component alignment and coronal femoral component alignment.MethodsWe retrospectively reviewed 77 knees in 71 patients who had undergone primary TKA for advanced osteoarthritis. All surgeries were performed by using a standard medial parapatellar approach. The osteotomy was performed with a conventional technique using an intramedullary rod for the femur and a mechanical extramedullary guiding system for the tibia. All patients enrolled in the study were evaluated with full-length lower extremity load-bearing standing scanograms, and the patients had preoperative and postoperative radiographs of the knees. Coronal femoral bowing angle (cFBA), sagittal femoral bowing angle (sFBA), and postoperatively, mechanical tibiofemoral angle of the knee (mTFA), β angle (femoral component flexion angle) were measured. The radiographic results of both groups were compared using Student's t test. A two-sided Pearson correlation coefficient was obtained to identify the correlations between FBA in the coronal and sagittal planes, as well as FBA and age or BMI, sFBA and β angle, cFBA and mTFA. Comparison of FSB incidence between different genders was made using Chi-square test. The p value < 0.05 indicates a statistically significant difference.ResultsThe mean sFBA, cFBA, β angle, mTFA were 9.34° ± 3.56°(range 1°–16°), 3.25° ± 3.79°(range − 7° to −17°), 3.91° ± 3.15°(range − 1° to −13°), 0.60° ± 1.95°(range − 3° to −6°), respectively. There was no correlation between age and sFBA (CC = 0.192, p = 0.194) or cFBA (CC = 0.192, p = 0.194); similarly, there was no correlation between age and sFBA (CC = 0.067, p = 0.565) or cFBA (CC = 0.069, p = 0.549). The sFBA was correlated with cFBA and β angle (CC = 0.540, p < 0.01; CC = 0.543, p < 0.01, respectively), and the cFBA was correlated with mTFA (CC = 0.430, p < 0.01). There was no significant difference (p = 0.247) of cFBA between the patients with sFSB and the patients without sFSB.ConclusionsThe current study showed that the sFBA was correlated with cFBA in the patients undergoing TKA and the patients with sFSB usually presented non-cFSB. We also found that sFSB could affect the femoral component alignment in the sagittal plane and cFSB could affect the femoral component alignment in the coronal plane. The sFBA or cFBA was not correlated with age, BMI, or gender.

Moderately elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) in patients with no clinical signs or symptoms of infection is not a contraindication for total knee arthroplasty: a retrospective cohort study

Background: It is unclear whether patients with elevated preoperative levels of erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) are more prone to periprosthetic joint infection (PJI) after total knee arthroplasty (TKA). The authors aimed to determine how preoperative moderate elevation of ESR or CRP in patients without clinical signs or symptoms of infection is associated with the risk of PJI after TKA surgery. Methods: In a prospective study, 315 patients who were elected for unilateral TKA were included, including 237 patients with preoperative normal ESR and CRP, 46 patients with moderate preoperative elevation of ESR (less than 50 mm/hr), and 32 patients with moderate preoperative elevation of CRP (less than 24 mg/dL). Patients with both ESR and CRP elevation were not included in the study. Primary TKA was done using a standard medial parapatellar approach under general anesthesia. Results: Overall rate of infection was 0.3% (1 in 320 patients) at a mean follow-up period of 19±5.3 mo. This infection occurred in a patient with normal preoperative ESR and CRP (1 in 237 patients, 0.4%). No infection occurred in 78 patients in either the ESR-elevated or the CRP-elevated group. Accordingly, the rate of infection was not significantly different between the two groups (P=0.83). Conclusions: Moderate preoperative elevations of ESR or CRP do not increase the rate of periprosthetic joint infection in patients undergoing total knee arthroplasty. Level of Evidence: Level III.

The influence of joint line position on functional outcome in primary total knee arthroplasty

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; To find out the cut off for position of joint line which will provide a good functional outcome.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods:&lt;/strong&gt; 58 patients underwent total knee arthroplasty using standard medial parapatellar approach were included in this study. Pre-operative and post-operative radiological joint line were assessed. Pre-operative and post-operative functional assessment were done using oxford knee score and International knee society score. functional outcome was assessed at 1, 3 and 6 months. Influence of post-operative joint line change on functional outcome was assessed on follow up visit in 6&lt;sup&gt;th &lt;/sup&gt;month.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; Of 58 patients studied, mean age ± SD was 69.0±7.5 years. Joint line elevation of 36, 16, 8 and 2 patients were between 0-2, 2-4 4-8 and&amp;gt;8 mm respectively with mean ± SD of joint line elevation of 2.24±2.07 mm in the group. Mean OKS-knee score at 6 months follow-up of study group was 36.60 with mean IKSS-knee score of 38.17 at 6 months follow up of group&amp;lt;4 mm which was significant (p&amp;lt;0.05) when compared to mean IKSS-knee score at 6 months follow up of group&amp;gt;4 mm (28.40).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; It was concluded that joint line restoration is necessary for getting a good functional outcome after primary total knee arthroplasty. The functional outcome of patients with joint line elevation between 4-8mm showed inferior outcomes in comparison to the patients with joint line elevation within 4 mm.&lt;/p&gt;

Lateral subvastus approach: A cadaveric examination of its potential for total knee arthroplasty

BackgroundLateral approaches to total knee arthroplasty (TKA) provide good surgical exposure and may provide greater ease of soft tissue balancing in patients with a valgus deformity; however, little is known about the versatility in non-valgus knees. The present study evaluated if a lateral subvastus approach can achieve adequate surgical exposure while maintaining less soft tissue damage compared with the medial parapatellar approach in knees without any significant deformity. MethodsUsing paired fresh-frozen cadaveric knees, the present study provides the first specimen-matched, side-by-side comparison of the lateral subvastus approach to the standard medial parapatellar approach to TKA. Ten knees were selected to undergo a lateral subvastus approach; the contralateral knee had a medial parapatellar approach as control. Incision length, surgical exposure and iatrogenic soft tissue damage were compared between the two approaches. ResultsThe lateral subvastus approach was successfully performed using an incision length that was not different from that used in the medial parapatellar approach (p > 0.05). The resultant surgical exposure was comparable between approaches (p > 0.05). The risk of the approach included tearing of the vastus lateralis fibers, and/or abrasion of the iliotibial tract/patellar ligament. ConclusionsThe lateral subvastus approach to TKA provided a comparable method to the standard medial parapatellar approach. Despite adequate exposure, the approach did risk soft tissue injury. Caution needs to be exercised to reduce the risk of iatrogenic injury to the vastus lateralis and surrounding ligaments. The successful implementation in this cadaveric study substantiates the need for further consideration of this approach in clinical practice.

The effect of anterior cruciate ligament resection on knee biomechanics.

The objectives of this study were to assess the effect of anterior cruciate ligament (ACL) resection on flexion-extension gaps, mediolateral soft tissue laxity, maximum knee extension, and limb alignment during primary total knee arthroplasty (TKA). This prospective study included 140 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess study outcomes pre- and post-ACL resection with knee extension and 90° knee flexion. This study included 76 males (54.3%) and 64 females (45.7%) with a mean age of 64.1 years (SD 6.8) at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1° varus (SD 4.6° varus). ACL resection increased the mean extension gap significantly more than the flexion gap in the medial (mean 1.2 mm (SD 1.0) versus mean 0.2 mm (SD 0.7) respectively; p < 0.001) and lateral (mean 1.1 mm (SD 0.9) versus mean 0.2 mm (SD 0.6) respectively; p < 0.001) compartments. The mean gap differences following ACL resection did not create any significant mediolateral soft tissue laxity in extension (gap difference: mean 0.1 mm (SD 2.4); p = 0.89) or flexion (gap difference: mean 0.2 mm (SD 3.1); p = 0.40). ACL resection did not significantly affect maximum knee extension (change in maximum knee extension = mean 0.2° (SD 0.7°); p = 0.23) or fixed flexion deformity (mean 4.2° (SD 3.2°) pre-ACL release versus mean 3.9° (SD 3.7°) post-ACL release; p = 0.61). ACL resection did not significantly affect overall limb alignment (change in alignment = mean 0.2° valgus (SD 1.0° valgus; p = 0.11). ACL resection creates flexion-extension mismatch by increasing the extension gap more than the flexion gap. However, gap differences following ACL resection do not create any mediolateral soft tissue laxity in extension or flexion. ACL resection does not affect maximum knee extension or overall limb alignment. Cite this article: Bone Joint J 2020;102-B(4):442-448.

Total Knee Arthroplasty for Valgus Deformity via a Lateral Approach: Clinical Results, Comparison to Medial Approach, and Review of Recent Literature

BackgroundTotal knee arthroplasty (TKA) for valgus deformity is a challenge. The standard medial parapatellar approach may not be universally useful for this. We have adopted the lateral approach to valgus knees. Here we describe our experience with this approach, present early results, and compare them to the medial approach. MethodsOur institutional registry was queried for all patients with valgus deformity who underwent a TKA via a lateral approach between 2013 and 2016. The registry was also queried for patients with valgus deformity who underwent a TKA through a medial approach in previous years and this data was compared to the study group. ResultsSeventy-nine valgus knees in 72 patients were operated through a lateral approach. Deformity was corrected by 10.8°, from 16.2° to 5.4° (P < .001). Patellar tilt improved from −2.3° to 0.3° (P = .037). Seven implants (9%) were constrained. Mean operating time was 87 minutes (range 53-137). Twenty-five knees in 23 patients were operated via the medial approach. Deformity was corrected by 7.3°, from 13.2° to 5.9° (P < .001). Mean operating time was 137 minutes (range 90-230). Constrained implants were used in 16% of cases. The lateral approach allowed better correction of valgus deformity (10.8 vs 7.3, P = .03) and shorter operative times (87 vs 137 minutes, P < .001). ConclusionA lateral approach TKA for valgus deformity improves knee alignment and patellar tilt. Compared to the medial approach, it allows better correction of the deformity, shorter operating times, and perhaps less use of constrained implants.

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.

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. 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. 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. 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.

Posterior cruciate ligament resection in total knee arthroplasty: the effect on flexion-extension gaps, mediolateral laxity, and fixed flexion deformity.

The aim of this study was to assess the effect of posterior cruciate ligament (PCL) resection on flexion-extension gaps, mediolateral soft-tissue laxity, fixed flexion deformity (FFD), and limb alignment during posterior-stabilized (PS) total knee arthroplasty (TKA). This prospective study included 110 patients with symptomatic osteoarthritis of the knee undergoing primary robot-assisted PS TKA. All operations were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess gaps before and after PCL resection in extension and 90° knee flexion. Measurements were made after excision of the anterior cruciate ligament and prior to bone resection. There were 54 men (49.1%) and 56 women (50.9%) with a mean age of 68 years (sd 6.2) at the time of surgery. The mean preoperative hip-knee-ankle deformity was 4.1° varus (sd 3.4). PCL resection increased the mean flexion gap significantly more than the extension gap in the medial (2.4 mm (sd 1.5) vs 1.3 mm (sd 1.0); p < 0.001) and lateral (3.3 mm (sd 1.6) vs 1.2 mm (sd 0.9); p < 0.01) compartments. The mean gap differences after PCL resection created significant mediolateral laxity in flexion (gap difference: 1.1 mm (sd 2.5); p < 0.001) but not in extension (gap difference: 0.1 mm (sd 2.1); p = 0.51). PCL resection significantly improved the mean FFD (6.3° (sd 4.4) preoperatively vs 3.1° (sd 1.5) postoperatively; p < 0.001). There was a strong positive correlation between the preoperative FFD and change in FFD following PCL resection (Pearson's correlation coefficient = 0.81; p < 0.001). PCL resection did not significantly affect limb alignment (mean change in alignment: 0.2° valgus (sd 1.2); p = 0.60). PCL resection creates flexion-extension mismatch by increasing the flexion gap more than the extension gap. The increase in the lateral flexion gap is greater than the increase in the medial flexion gap, which creates mediolateral laxity in flexion. Improvements in FFD following PCL resection are dependent on the degree of deformity before PCL resection. Cite this article: Bone Joint J 2019;101-B:1230-1237.

Anatomical and finite element analysis of anterior cruciate ligament reconstruction within biomechanical insertion

To provide new concepts of anterior cruciate ligament (ACL) reconstruction by anatomical gross observation of ACL tibial insertion and finite element analysis of distribution of ACL mechanical insertion. In the anatomical study, ten fresh adult cadaveric knees were dissected, including 6 males and 4 females, all knees were generally observed through standard medial parapatellar approaches, paying attention to the close anatomical relationship of tibial insertion and anterior horn of lateral meniscus, and ACL was exposed and gradually removed from the inside. The shape of tibial insertion of ACL was observed and recorded, and anterior-posterior diameters and left-right diameters of tibial insertion were measured with vernier caliper. For the study of finite element analysis, three-dimensional thin-layer magnetic resonance imaging of normal knee joint was used to establish knee joint model. Three-dimensional reconstruction software MIMICS and finite element analysis software ANSYS were used to establish knee joint model, subsequently, clinical physical examination Lachman test and pivot-shift test were simulated to observe the force distribution of ACL tibial insertion and femoral insertion. The ACL tibial mechanical insertion was rather flat and long similar as an arc shape without a clear separation between anterior medial bundle (AMB) and posterolateral bundle (PLB) in gross observation. The dense fibers lies belonged to the medial intercondylar ridge and ended up anterior with the osseous landmark of anterior ridge. Its average anterior-posterior diameter was (13.8±2.0) mm, the average left-right diameter of midsubstance was (5.3±0.6) mm, and the average left-right diameter of anterior margin was (11.5±1.2) mm. The finite element analysis showed that distribution on the femoral side was oval shape mainly below the residents' ridge, while the tibial side was rather flat mainly along the medial intercondylar ridge, which was consistent with the anatomical observation. The biomechanical characteristics of ACL attachments were verified theoretically. Anatomical study and finite element analysis have confirmed the flat arc shape of ACL tibial insertion. The ideal reconstruction technique of ACL should be based on its biomechanical insertion. Based on anatomical study and biomechanical analysis, we have proposed the idea of ACL biomechanical insertion reconstruction (BIR) and established a surgical model with oval femoral tunnel and rounded-rectangle tibial tunnel.

The Extensile Medial Parapatellar Approach to the Distal Femur and Knee: Anatomic Landmarks and Surgical Technique

This paper describes an extensile surgical approach to the distal femur, which incorporates the medial parapatellar arthrotomy. This extensile exposure serves as an anterior utility approach to the knee, allowing the surgeon access to all aspects of the anterior knee and near circumferential access to the distal femur. Reported indications for access to this region include: tumor resection, difficult primary arthroplasty and revision arthroplasty of the knee, and intra-articular and extra-articular fractures of the distal femur. Despite adequate working knowledge of the standard medial parapatellar approach to the knee, the extensile approach is seldom required and, as a result, orthopedic trainees and practising orthopedic surgeons may not be familiar with the musculotendonous junctions that occur in the quadriceps tendon. This report describes a novel surgical approach and the relevant anatomy through a series of detailed clinical and fresh cadaveric dissections. A previously undescribed anatomic landmark is demonstrated through photographs and cadaveric variation studies, which may help guide the surgeon in defining crucial planes.

Incidence of Femoral Component Malrotation Using Posterior Condylar Referencing in Total Knee Arthroplasty.

Proper femoral component rotation in total knee arthroplasty (TKA) is important, given the prognostic impact of a poorly positioned component. The purpose of this observational study was to determine the incidence of femoral component malrotation using posterior condylar axis (PCA) referencing. A total of 100 knees in 92 patients with varus gonarthritis of the knee undergoing primary TKA using a standard medial parapatellar approach were evaluated intraoperatively. After distal femoral resection, the standard femoral sizing guide referencing the posterior condylar axis was used to set femoral component rotation. This was then compared with both the transepicondylar (TEA) and trochlear anteroposterior axes (TRAx). Disparites were recorded and corrected in line with the epicondylar axis. Rotational adjustment for addition of further external rotation was made in 13 (13.0%) cases. In seven cases, the medial pin sites were raised between 1 and 3 mm, and in six cases, the lateral pin site was lowered between 1 and 3 mm (based on risk of notching the femoral cortex). It is critical to not rely exclusively on the PCA to confirm rotational positioning of the femoral component as predicted by posterior condylar referencing guides. Intraoperative adjustment and confirmation using the TEA and TRAx occurred in 13% of primary TKA cases, which might have, otherwise, had a significant effect on the clinical outcome.

The Role of Complete Posterior Cruciate Ligament Release in Flexion Gap Balancing for Total Knee Arthroplasty

BackgroundThe sequence of posterior cruciate ligament (PCL) release in posterior-substituting designs, when performing gap balancing in total knee arthroplasty (TKA), is variable. We hypothesize that early complete PCL release during knee exposure will change the flexion balance to result in a uniform medial-lateral flexion gap symmetry at the time of implant placement. MethodsTen cadaveric knees were prepared for TKA using standard medial parapatellar approach. Medial and lateral flexion gaps were measured in the conditions of intact, partial (50%) resection, and full resection of PCL. Measurements were performed with both surgical navigation and a caliper. Flexion gap distances were reported for medial and lateral compartments in the 3 PCL conditions. ResultsMedial flexion gap increased after only complete release of the PCL (mean 3.94-5.05 mm). The lateral flexion gap increased as well (mean 4.17-4.67 mm). Complete PCL release resulted in a statistically significant increase in medial flexion gap compared to intact (P = .013) and partially released (P = .012) specimens. No significant differences were noted in lateral flexion gap change. Notable change in medial versus lateral gap (flexion gap symmetry) relationship occurred after just partial PCL release (P = .018). ConclusionAmong the 3 PCL states, changes in flexion gap distance were most conspicuous in the medial compartment. This suggests gap balancing performed with incomplete PCL release will not accurately reflect gap distance after eventual PCL removal, thus supporting the hypothesis. It is recommended that the PCL should be released to the fullest extent possible before ligament tensioning for femoral component rotation in posterior-stabilized TKA.