Patellar Height Research Articles

Radiographic Investigation of Coronal Plane and Patellar Height and Changes Following Tibial Deflection Osteotomy for Correction of Tibial Slope in Combination With ACL Reconstruction

Background: A tibial deflexion osteotomy (TDO) is performed to decrease the sagittal tibial slope to reduce the relative risk of anterior cruciate ligament (ACL) reconstruction (ACLR) graft failure. Given that coronal plane osteotomies can cause consequential changes in the sagittal plane to patellar height and tibial slope, potential changes to coronal plane alignment and patellar height can result after a sagittal plane osteotomy. Purpose: To compare preoperative and postoperative coronal plane alignment after TDO, as well as to analyze the effect of the osteotomy on patellar height. Study Design: Case series; Level of evidence, 4. Methods: This study was conducted on a consecutive series of patients with primary and revision ACLR with concomitant TDO between 2011 and 2022. Inclusion criteria were 1-stage autograft ACLR combined with supratubercular TDO with pre- and 3 months postoperative radiographs of sufficient quality. Indications for TDO were anterior instability requiring ACL revision surgery and a posterior tibial slope (PTS) >9° or a PTS >14° in the primary ACL surgery patients. Anteroposterior and lateral knee radiographs were reviewed, and the medial proximal tibial angle (MPTA), PTS, Caton-Deschamps index (CDI), and modified Insall-Salvati ratio were measured directly from the radiographs by 2 independent reviewers. Results: A total of 68 patients were included in this study. Pre- and postoperative radiographs were performed 1 month before and 3 months after surgery, respectively. There was a significant increase in the mean MPTA of 0.95° varus (SD, 2.1°; range, increase of 4.23° valgus to increase of 7.74° varus; P < .01), a decreased PTS of 8.86° (SD, 3.03°; P < .01), and an increased CDI of 0.08 (range, decrease of 0.27 to increase of 0.64) (P < .01; SD, 0.17) in patients undergoing TDO. Insall-Salvati ratio measurements showed no difference. There was good intra- and interobserver reliability, with intraclass correlation coefficients of 0.97 and 0.91 for MPTA, 0.97 and 0.87 for PTS, 0.87 and 0.93 for CDI, and 0.88 and 0.76 the Insall-Salvati ratio. Conclusion: This study, the largest series on TDO for ACLR, demonstrates that the TDO can be performed safely without large changes to coronal alignment or patellar height. The tibial slope was reduced by a mean of 8.86° (range, 2.3°-11.5°; P < .01). The TDO produces a small statistically significant change to coronal alignment, inducing a mean increased varus of <1° and an increased patellar height of 0.1 CDI. Therefore, TDO can be performed safely without dramatic changes to coronal alignment or patellar height, this study highlights technical aspects to minimize iatrogenic varus.

Mako versus ROSA: comparing surgical accuracy in robotic total knee arthroplasty.

There is increasing adoption of robotic surgical technology in Total Knee Arthroplasty. The ROSA® knee system can be used in either image-based mode (using pre-operative calibrated radiographs) or imageless modes (using intra-operative bony registration). The Mako knee system is an image-based system (using a pre-operative CT scan). This study aimed to compare surgical accuracy between the ROSA and Mako systems with specific reference to joint line height, patella height, posterior condylar offset and tibial slope. This was a retrospective review of a prospectively collected data of the initial 50 consecutive ROSA TKAs and the initial 50 consecutive Mako TKAs performed by two high-volume surgeons. To determine the accuracy of component positioning, the immediate post-operative radiograph was reviewed and compared with the immediate pre-operative radiograph with regards to joint line height (JLH), patella height (PH), tibial slope (TS) and posterior condylar offset (PCO). Mean difference between pre- and post-operative radiographs using the ROSA knee system of joint line height was 0.47mm (SD 0.95) posterior condylar offset 0.16mm (SD 0.76), tibial slope 0.9 degrees (SD 1.6) and patella height 0.01 (SD 0.05). Mean difference using the MAKO knee system of joint line height was 0.26 (SD 1.08), posterior condylar offset -0.26mm (SD 0.78), tibial slope 1.8 degrees and patella height 0.03. No significant difference was demonstrated between the accuracy of component positioning of the ROSA or MAKO knee systems. Our study is the first study to compare the accuracy of the ROSA and MAKO knee systems in total knee arthroplasty. Both systems are highly accurate in restoring native posterior condylar offset, joint line height, tibial slope and patella height in TKA with no significant difference demonstrated between the two groups.

Patellar height: an important parameter in knee MRI associated with tendinopathy, quadriceps fat pad edema (QFPE), anterior cruciate ligament mucoid degeneration (ACL-MD), and lateral cartilage damage.

Some pathologies associated with abnormal patellar height have been reported in the literature. However, its relationship with some pathologies, such as anterior cruciate ligament mucoid degeneration (ACL-MD) and focal cartilage defect, has not been investigated. To investigate the relationship between patellar height with patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and focal cartilage defect. Magnetic resonance imaging of the knees of 261 patients were classified into three groups as normal, patella alta, and patella baja, and evaluated in terms of patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and focal cartilage defect. There were 261 patients (140 men, 121 women; age range = 18-60 years; mean age = 30 ± 4.7 years). Of the 261 patients, 181 (69.3%) were normal, 56 (21.4%) were patella alta, and 24 were patella baja (9.1%). Patellar-quadriceps tendinopathy, quadriceps fat pad edema, and ACL-MD rates were significantly higher compared to the normal group (P <0.05). While a moderate positive correlation was found between patellar height shift and patellar-quadriceps tendinopathy and ACL-MD, there was a small correlation between patellar height shift and quadriceps fat pad edema. The rate of focal cartilage defect was significantly higher in the middle part of the lateral femoral condyle and lateral knee joint only in patella alta. The risk of patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and lateral focal cartilage defect is higher in patients with alta-baja. The radiologist should evaluate these pathologies more carefully, especially subtle ones, in patients with abnormal patellar height.

Economic evaluation of high tibial osteotomy: Closing wedge is more cost-effective than open wedge technique when analysing the KOOS-12 improvement.

The purpose of this study was to compare the cost-effectiveness of two techniques for performing a knee valgus osteotomy: opening wedge high tibial osteotomy (OW-HTO) vs closing wedge high tibial osteotomy (CW-HTO). In this economic evaluation study, a cost-effectiveness analysis from the perspective of the Spanish public healthcare system was performed, comparing OW-HTO with CW-HTO. All patients with medial knee osteoarthritis who underwent one of these procedures between 2018 and 2020 in our institution were included. The cost analysis included operating room, implant, graft and hospital admission costs. Functional outcomes (KOOS-12, Tegner activity scale, pain and satisfaction) and radiological outcomes (hip-knee-ankle angle, medial proximal tibial angle, tibial slope and patellar height) were analysed. The cost-effectiveness ratio was obtained by calculating the cost of improving the minimal clinically important difference (MCID) of KOOS-12 for each procedure. All costs are expressed in 2020 euros. Fifty-one patients met the inclusion criteria (27 OW-HTO and 24 CW-HTO). Good to excellent functional outcomes, significant pain reduction (>6 points) and high patient satisfaction (>9/10) were observed in both groups. Both techniques yielded excellent radiological outcomes. N.s. differences in functional or radiological outcomes improvements between both procedures were found. However, the OW-HTO group presented a higher total cost than the CW-HTO group (4612.1 ± 765.6€ vs. 1827.1 ± 701.9€; p < 0.001). The cost-effectiveness ratio was 818.1 ± 46.8 €/MCID for the CW-HTO procedure and 2414.3 ± 115.2 €/MCID for the OW-HTO procedure (p = 0.025). The CW-HTO procedure presented a cost-effectiveness ratio almost three times lower than the OW-HTO procedure. Both techniques allowed to achieve of good to excellent functional outcomes, significant pain reduction and high patient satisfaction while correcting the varus limb malalignment and the metaphyseal tibial varus in patients with medial compartment osteoarthritis. Level III; economic study.

Revision Patellar Tendon Reconstruction Using Hamstring Tendon Autograft

Background: Patellar tendon ruptures presenting in a chronic setting are rare events that impose technical surgical challenges due to proximal retraction of the patella, quadriceps muscle atrophy and contracture, and peripatellar adhesions. Various reconstruction techniques have been described using different grafts and fixation methods; however, there is a paucity of reported outcomes and there is no consensus on standard of care. Indications: The patient is a 36-year-old man who presented with a failed patellar tendon reconstruction 14 months after his initial surgery (performed 1 year after the initial injury) with functional weakness and loss of extension. The patient was indicated for a revision patellar tendon reconstruction due to persistent functional limitations. Technique Description: The revision patellar tendon reconstruction was performed with gracilis and semitendinosus tendon autografts harvested from the ipsilateral limb. Hardware was removed from the initial graft tunnels in the tibial tubercle and patella. Patellar height was estimated using fluoroscopic measurement of the contralateral patellar tendon length. The graft is first passed through the patellar tunnel, and the individual limbs of the graft are then both placed through the tibial tubercle tunnel. A sternal wire in a figure-of-eight configuration was used to progressively distalize the patella to match the native patellar height, and the graft was then tensioned and secured together. Results: The patient regained full range of motion at 2-year follow-up and was able to return to work and activities without functional limitations. Recent case series also using ipsilateral hamstring tendon autograft for chronic patellar tendon reconstruction report improved patient outcome scores, normal Insall-Salvati index, improved quadriceps strength, and high levels of patient satisfaction. Discussion/Conclusion: Chronic patellar tendon ruptures are technically challenging to treat, especially in the context of revision of a failed reconstruction. The technique presented in this video may aid orthopaedic surgeons in treating this rare but debilitating injury. Given the lack of high-quality evidence, future studies are needed to explore graft choices, graft fixation techniques, and postoperative protocols. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Effect of accelerated postoperative rehabilitation after tibial tubercle distalisation: A randomised controlled trial protocol.

Patella alta is a clinical condition where the patella is positioned too proximal in relation to the femoral trochlea. Such an abnormality may cause patellar instability and predispose to recurrent patellofemoral dislocations and patellofemoral pain. There are no conclusive guidelines for determining a threshold for too high positioned patella, as several different methods have been described to measure patellar height. As a surgical solution, distalising tibial tubercle osteotomy has been described to correct excessive patellar height. In the early phase of the distalising tibial tubercle osteotomy postoperative protocol, weightbearing and knee flexion are limited with a brace commonly for 4-8 weeks to avoid potential implant failure leading to displacement of the osteotomy or non-union. The potential risks for adverse effects associated with the limitation rehabilitation protocol include a delay in regaining knee range of motion, stiffness and muscle weakness. As a result, recovery from surgery is delayed and may lead to additional procedures and long-term morbidity in knee function. This is a prospective, randomised, controlled, single-blinded, single centre trial comparing a novel accelerated rehabilitation protocol with the traditional, motion restricting rehabilitation protocol. All skeletally mature patients aged 35 years and younger, referred to as the distalising tibial tubercle osteotomy procedure group, are eligible for inclusion in the study. Patients will be randomised to either the fast rehabilitation group or the traditional rehabilitation group. Patients with patellar instability will be additionally treated with medial patellofemoral ligament reconstruction. The hypothesis of the trial is that the novel accelerated rehabilitation protocol will lead to faster recovery and improved functional outcome at 6, 12 and 24 weeks compared with the conservative rehabilitation protocol. A secondary hypothesis is that the complication rate will be similar in both groups. The study will document short-term recovery and the planned follow-up will be 3 years. After the 1-year follow-up, the trial results will be disseminated in a major peer-reviewed orthopaedic publication. Protocol version 3.6, date 28/11/2023.

"Coronal Split/Overlap Repair" Patellar Tendon Shortening in Skeletally Immature Patients.

"Coronal split/overlap repair" patellar tendon shortening (PTS) is a technique that is utilized to treat patella alta and can be combined with distal femoral extension osteotomy (DFEO) for the treatment of crouch gait in skeletally immature patients with cerebral palsy. The patellar tendon is split in the coronal plane. The ventral patellar tendon flap is released from its patellar attachment and is reflected distally over its tibial attachment, exposing a dorsal flap. Two patellar/tibial no. 5 Ethibond (Ethicon) sutures are passed through 2 crossing patellar tunnels and 2 parallel tibial tunnels. The patella is then pushed distally until its distal pole lies at the level of the tibiofemoral joint. The Ethibond sutures are tied and tensioned to the desired level. The knee should be able to be passively flexed to 90°. The intact redundant dorsal flap of the patellar tendon is imbricated. Lastly, the ventral flap is advanced proximally and sutured to the anterior surface of the patella and to the edges of the dorsal flap without shortening. A hinged knee brace is utilized postoperatively with a range of motion of 0° to 30°, progressing to 90° by 6 weeks. No resistive quadriceps contractions are permitted for the first 3 weeks. Patellar tendon advancement in skeletally immature patients can be performed by releasing the tibial attachment and the free end is advanced deep to the T-shaped tibial periosteal flap1-3. Other PTS techniques can be grouped into the categories of (1) patellar tendon imbrication4, (2) patellar tendon detaching techniques in which the tendon is detached from the patellar attachment or cut in its midsubstance and shortened2,5-7, and (3) patellar tendon semi-detaching techniques in which patellar tendon flaps are created and shortened8,9. The presently described technique is a semi-detaching technique, preserving a good part of the patellar tendon while avoiding complete dehiscence of the extensor mechanism. Moreover, the 2 patellar/tibial sutures would protect the patellar tendon repair and allow early rehabilitation and knee range-of-motion exercises. Satisfactory correction of the patella alta was reported with PTS techniques with or without DFEO to correct concomitant fixed flexion deformity in patients with cerebral palsy. Furthermore, there was reported improvement of total knee range of motion with restoration of adequate knee extension during the stance phase1,3,8. Reported complications with this technique were mainly superficial infection. Any substantial fixed flexion deformity of the knee (>10°) should be corrected with hamstring lengthening or DFEO prior to PTS.A mid-patellar coronal split is made with use of a no.-15 blade and extended proximally and distally with use of 2 mosquito clips.To avoid difficulties with crossing of the patellar sutures, always keep the straight needle inside the 1st tunnel until the 2nd tunnel is created and its respective suture is passed.To distalize the patella, the patellar/tibial sutures are tied in a simple knot and held by a mosquito clip in order to allow retensioning until the desired patellar height is reached.The 2 patellar/tibial suture knots are slid to the proximal and distal ends of the surgical field. 3DGA = 3-dimensional gait analysisADL = activities of daily livingCP = cerebral palsyCPM = continuous passive motionDFEO = distal femoral extension osteotomyFAQ = Functional Assessment QuestionnaireFMS = Functional Mobility ScaleGMFCS = Gross Motor Function Classification SystemGMFM = Gross Motor Function MeasureGPS = Gait Profile ScoreGVS = Gait Variable ScoreK-wires = Kirschner wiresPTA = patellar tendon advancementPTS = patellar tendon shorteningSEMLS = single event multi-level surgery.

Femoropatellar alterations in knees with chronic anterior cruciate ligament injuries: a radiographic analysis

Background: The objective of this study was to correlate the occurrence of patellofemoral malalignment in a chronic anterior cruciate ligament (ACL) deficient knee using common radiological parameters. Methods: A case-control study was conducted on 35 adult patients with previously diagnosed unilateral chronic ACL injury. The injured knee was considered as the case, while the contralateral normal knee served as the control. Radiological parameters including the Caton-Deschamps patellar height index, Merchant patellar congruence angle, and Laurin lateral patellar tilt angle were measured on X-rays obtained from both normal and ACL injured knees. A comparative analysis was performed between the two groups. Results: The Caton-Deschamps patellar height index had a mean value of 0.95±0.05 in the ACL-deficient knee. The Merchant patellar congruence angle showed mean values of 12.66±0.84 degrees in the ACL injured knee, while the Laurin lateral patellar tilt angle was 8.06±1.41 degrees in knees with ACL failure. These results indicate lower patellar height, greater lateral displacement of the patella, and increased lateral patellar tilt in knees with chronic ACL tears, thereby affecting the patellofemoral joint. Conclusions: Chronic ACL tears are associated with patellofemoral malalignment, characterized by decreased patellar height, increased lateral displacement of the patella, and greater lateral patellar tilt, thus impacting the patellofemoral joint.

Patellar Fracture Forces Are Not Affected by Proximal Versus Distal Bone Block Anterior Cruciate Ligament Reconstruction Harvest Sites in a Cadaveric Model

To quantify the maximum load to fracture in patellae from which bone-patellar tendon-bone (BPTB) and bone-quadriceps tendon (BQT) autografts have been harvested for anterior cruciate ligament reconstruction in a cadaveric model. Forty-six fresh-frozen patellae were isolated and divided into the BPTB harvest and BQT harvest groups with matching based on donor age and sex. Computed tomography scans were obtained to calculate bone mineral density (BMD) and patellar height, width, and thickness. BPTB and BQT grafts were harvested from the inferior patella and superior patella, respectively, and then ramped to failure in a 3-point bend test configuration to simulate a postoperative fracture produced by a direct impact after a fall. The presence of fracture, fracture pattern, and maximum load to fracture were recorded. Donor demographic characteristics; patellar height, width, and thickness; and maximum load were compared by the Student t test. Pearson correlations were used to determine whether maximum load was affected by BMD or patellar morphology. The level of significance was set at P < .05. Maximum load to fracture was not significantly different (P= .91) between the BPTB (5.0 ± 2.3 kN) and BQT (5.1 ± 2.6 kN) groups. Maximum loadto fracture in the BPTB group did not correlate with BMD (P= .57) or patellar measurements (P= .57 for thickness, P= .43 for width, and P= .45 for height). Maximum load to fracture in the BQT group positively correlated with BMD and negatively correlated with patellar height. Maximum load to fracture in the BQT group did not correlate with patellar thickness or width. Fracture through the harvest site was observed in 87% of BPTB specimens and 78% of BQT specimens. The location of the BPTB or BQT autograft harvest site did not significantly affect patellar load to fracture in a cadaveric model. It is important to understand patellar morphology and the effect of BPTB and BQT graft harvest-site locations on the biomechanical strength of the patella after anterior cruciate ligament reconstruction.

Using the Blackburne-Peel index to measure the patellar height on magnetic resonance images

To reveal the normal values of patellar height measurements using the Blackburne-Peel index on magnetic resonance (MR) images and to show the gender and age differences regarding this measurement technique. This retrospective cross-sectional study investigated 148 knee MR images, and those images were re-evaluated to find out the normal values of patellar height using the Blackburne-Peel index (BPI). An adapted measurement technique of this index was applied to MR images. The study group was analyzed regarding the sex and age differences, correlation with age was investigated, and all descriptive data were presented. Independent Samples T-test, Kruskal–Wallis variance analysis, and Spearman’s Rho correlation test was applied to calculate the results. The mean value was 0.80 ± 0.09 for the total of patients. The measurements regarding the height of the inferior edge of the patella articular surface and the length of the patella articular surface indicated a significant difference between females and males (p < 0.001 for both measurements). The descriptive data obtained from this study revealed the mean values of the whole study group, different sexes, and age groups separately. Additional studies are needed for adapting BPI on MR images and verifying the normal values of the population.

Maintaining Posterior Tibial Slope and Patellar Height During Medial Opening Wedge High Tibial Osteotomy

Background: Increased posterior tibial slope (PTS) and decreased patellar height (PH) after medial opening wedge high tibial osteotomy (MOWHTO) have been repeatedly reported in the literature. However, this has been disputed in more recent biomechanical studies. Hypothesis: No change in PTS or PH would result after MOWHTO with the freehand technique, regardless of the degree of the coronal plane correction. Study Design: Case series. Methods: A total of 62 patients who underwent MOWHTO between 2018 and 2020 were included. Surgery was performed using a dedicated step-by-step protocol to reduce the risk of unintentional slope changes. All patients were evaluated preoperatively and at a 2-year follow-up with the Knee injury and Osteoarthritis Outcome Score and the University of California, Los Angeles physical activity scale. Pre- and postoperative radiographic lower limb alignment parameters—including hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), mechanical lateral distal femoral angle, proximal posterior tibial angle (PPTA), joint line convergence angle, and joint line obliquity—were measured on full-length lower limb radiographs. PH measurements assessed on lateral and anteroposterior knee radiographs included the Caton-Deschamps, Insall-Salvati, and Schröter indices. Results: A significant change was observed in the coronal plane alignment, with an increase in the MPTA from 84.38° to 90.39° ( P &lt; .001) and a consequent increase in the HKA from 172.19° to 180.15° ( P &lt; .001). No significant changes were observed in the PTS, as evidenced by a postoperative PPTA of 80.6° versus a preoperative value of 80.4° ( P = .2). No significant changes were detected in the mean PH on all 3 indices used—pre- versus postoperative Caton-Deschamps, Insall-Salvati, and Schröter indices measured 0.95 versus 0.93 ( P = .2), 1.03 versus 1.03 ( P = .5), and 1.56 versus 1.54 ( P = .3), respectively. Conclusion: In this study, MOWHTO did not result in significant changes in the PTS or PH when accurate preoperative planning and precise intraoperative freehand technique were adopted..

The larger patellar tilt angle and lower intercondylar notch angle might increase posterior cruciate ligament injury risk: a retrospective comparative study

BackgroundPosterior cruciate ligament (PCL) injuries are common ligament injuries of the knee, and previous studies often focused on the associations between the morphology of the knee and PCL injuries. Studies on the correlation between PCL injuries and patellofemoral alignment are limited.MethodsThis retrospective study included 92 patients with PCL injured and 92 patients with PCL intact. Measurement parameters were compared between the two groups, including patellar tilt angle, congruence angle, patellar height, hip-knee-ankle angle, lateral trochlear inclination, femoral condyle ratio, bicondylar width, intercondylar notch width and index, notch angle, trochlear facet asymmetry, and trochlear sulcus depth and angle. Independent risk factors associated with PCL injuries were identified by logistic regression analyses.ResultsIn the PCL injured group, the patellar tilt angle was significantly larger (13.19 ± 5.90° vs. 10.02 ± 4.95°, P = 0.04); the intercondylar notch angle was significantly lower (60.97 ± 7.83° vs. 67.01 ± 6.00°, P = 0.004); the medial and lateral femoral condyle ratio were significantly larger (0.63 ± 0.64 vs. 0.60 ± 0.56, P = 0.031; 0.65 ± 0.60 vs. 0.58 ± 0.53, P = 0.005) than in the PCL intact group. There were 11 patients with patellar dislocation in the PCL injured group, accounting for 12%. In these patients, the patellar height was higher (1.39 ± 0.17 vs. 1.09 ± 0.25, P = 0.009); the trochlear sulcus angle was larger (157.70 ± 8.7° vs. 141.80 ± 8.78°, P < 0.001); and the trochlear sulcus depth was shallower (3.10 ± 1.20mm vs. 5.11 ± 1.48mm, P = 0.003) than those in the patients without patellar dislocation. Multivariate analyses showed that patellar tilt angle (each increase 1 degree, OR = 1.14) and intercondylar notch angle (each increase 1 degree, OR = 0.90) were independent risk factors for PCL injuries.ConclusionThe patients with PCL injuries had larger patellar tilt angles, lower intercondylar notch angles, and longer posterior femoral condyles than patients with PCL intact. The larger patellar tilt angle and lower intercondylar notch angle might be risk factors for PCL injuries.

A comparison of joint line height after revision total knee replacement using a rotating hinge versus a condylar revision knee system

PurposeThis retrospective study aimed to assess the effects of two differing revision total knee implants designs (condylar and rotating hinge) on joint line height. MethodThe use of distal augmentation and pre and post revision radiographic joint line heights were compared in 19 condylar type knee replacements (Zimmer NexGen Legacy Constrained Condylar Knee - LCCK) and 40 LINK-Endo-rotating hinge knee replacements. Joint line and patellar heights were determined for each implant using four validated methods. For comparison within a group a two tailed paired Student's t-test was used, for comparison between the groups an unpaired, two tailed Student's t-test was used. A p value of less than 0.05 was deemed statistically significant. ResultsIn 15 of 19 NexGen revision knee replacements distal augments were used. No distal augments were used in the LINK-Endo RHK group. In both systems there was no tendency to elevate the joint line relative to the tibia. The joint line was distalised relative to the femur in the NexGen group and proximalised in the rotating hinge knee group. Measurements using antero-posterior radiographs were found to be the most reliable method of assessing joint line height when compared to lateral radiographs. ConclusionBoth revision knee implant systems adequately restored joint line height. In condylar type knee revision implants elevation of the joint line height may be avoided through the use of distal augmentation. We found AP radiographs to be the most reliable method of accurately assessing joint line height.

A Novel Patellar Tendon Reconstruction Technique Using Semitendinosus Allograft

A Novel Patellar Tendon Reconstruction Technique Using Semitendinosus Allograft

Patellar Dislocation in Adolescent Patients: Influence on Cartilage Properties Based on T1ρ Relaxation Times

Background: Adolescents who experience a patellar dislocation have an elevated risk of patellofemoral posttraumatic osteoarthritis. Magnetic resonance imaging (MRI)–based T1ρ relaxation times were measured for adolescents to evaluate patellofemoral cartilage after patellar dislocation. Long T1ρ relaxation times are an indicator of cartilage degradation. Hypothesis: The primary hypothesis is that patellofemoral cartilage T1ρ relaxation times will be elevated in the acute phase after patellar dislocation. The secondary hypothesis is that T1ρ relaxation times will be higher for knees with multiple rather than single dislocations due to repeated traumatic injury. Study Design: Cross-sectional study; Level of evidence, 3. Methods: In total, 23 adolescents being treated for a recent patellar dislocation, 13 for a first-time dislocation (47 ± 38 days since most recent dislocation) and 10 for multiple dislocations (55 ± 24 days since most recent dislocation), and 10 healthy controls participated in MRI-based T1ρ relaxation time mapping. For multiple regions of the patellofemoral joint, mean T1ρ values were compared between the 3 groups with multiple group comparisons and post hoc tests. T1ρ relaxation times were also correlated against measures of patellofemoral anatomy and alignment for single and multiple dislocations. Statistical significance was set at P < .05. Results: T1ρ relaxation times were significantly longer for injured knees (single and multiple dislocations) than controls at the medial and central patella and central trochlear groove. For the regions on the patella, significant differences between injured and control knees exceeded 15%. No significant differences were identified between single and multiple dislocations. For the initial dislocation group, T1ρ relaxation times within multiple regions of the patellofemoral joint were significantly correlated with lateral patellar alignment or patellar height. Conclusion: Elevated patellofemoral cartilage T1ρ relaxation times are consistent with a high risk of long-term patellofemoral osteoarthritis for adolescents who experience patellar dislocations. T1ρ relaxation times were elevated for multiple regions of patellofemoral cartilage. T1ρ relaxation times were expected to increase with additional dislocation episodes, but relaxation times after single and multiple dislocations were similar. After a first dislocation, parameters related to patellar maltracking were correlated with cartilage degradation.

Can Anterior Knee Pain Be Explained by Patella Position After Infrapatellar Tibia Intramedullary Nailing?

The objective of this study is to investigate the postoperative position of the patella and its relationship with anterior knee pain in patients operated with infrapatellar reamed tibia intramedullary nailing (IMN). Patients who underwent tibia IMN between 2019 and 2022 and who had anterior knee pain in their postoperative follow-up at least two outpatient clinic controls with an interval of at least one month were examined. Patellar height indices (Insall-Salvati, Blackburne-Peel, Caton-Deschamps, and modified Insall-Salvati) and sagittal angulation (patella-patellar tendon angles) were measured on the lateral direct radiographs of the patients in semi-flexion. As a control group, measurements were made on the contralateral intact extremity radiographs of the same patients. There was no significant difference in patellar height indices between the fractured and intact sides in any of the patients (p = 0.588; p = 0.747; p = 0.446; p = 0.573, respectively). When the sagittal angulations were analyzed, a significant difference was found between the fractured and intact sides of the patients (p = 0.048), resulting in an approximate three-degree change. Patellar sagittal balance has been identified as one of the contributing factors to the development of anterior knee pain following reamed tibial IMN. Further biomechanical and comprehensive clinical studies are needed on this subject.

A Supratuberosity Anterior Closing-Wedge Proximal Tibial Osteotomy Increases Patellar Height: A Simulated Time Zero Uniplanar Radiographic Study

PurposeThe purpose of this time-zero radiographic study was to simulate the effect of supra-tuberosity tibial anterior closing wedge osteotomy (ACWO) in knees with posterior tibial slope (PTS) ≥12° on patellar height when aiming for a target PTS of 5°. MethodsThe authors retrospectively reviewed true lateral radiographs of the knees of skeletally mature patients scheduled for primary anterior cruciate ligament reconstruction (ACLR), and included all knees with excessive PTS (≥12°). Coordinates of 11 landmarks were digitized to calculate patellar height (Caton-Deschamps index, CDI) and mid-shaft posterior tibial slope (mPTS). The change in patellar height following a simulated supra-tuberosity ACWO was calculated and compared for knees with patella norma versus alta. A linear univariable regression model predicted the effect of change in mPTS on CDI. ResultsIn the final cohort of 83 patients, a simulated supra-tuberosity ACWO increased CDI from 1.13 (range, 0.73 to 1.74) to 1.29 (range, 0.84 to 1.91; p<0.001). In 56 patients with patella norma, a simulated supra-tuberosity ACWO increased CDI from 1.02 (range, 0.73 to 1.19) to 1.18 (range, 0.84 to 1.41; p<0.001), whereas in patients with patella alta, a simulated supra-tuberosity ACWO increased CDI from 1.33 (range, 1.20 to 1.74) to 1.52 (range, 1.36 to 1.91; p<0.001). The linear regression model revealed that a 1° decrease in mPTS increased CDI by 0.02. ConclusionSimulation of a supra-tuberosity ACWO revealed that the procedure increases patellar height in all knees, but did not induce significant differences in patellar height characteristics between knees with patella norma versus alta. A linear regression model revealed that a 1° decrease in mPTS could theoretically increase CDI by 0.02.

Patients with bilateral patellar instability have multiple and symmetric risk factors in each knee.

Bilateral involvement is common in patients with patellar instability. The management of bilateral patellar instability is associated with increased complication rate. The higher complication rate in this cohort may be related to the presence of underlying anatomic risk factors. The purpose of the study was to evaluate the presence and side-to-side differences in risk factors between knees in bilateral patellar instability. In a retrospective study (2008-2017), demographic information, characteristics of patellar dislocation and anatomic risk factors on MRI (trochlear dysplasia, patellar height, tibial tubercle lateralization, patellar tilt, sulcus angle, bump height) were evaluated in both knees of all patients (n = 32, 15 males and 17 females) with bilateral patellar instability. The risk factors were analyzed based on established cut off values and were compared between gender, laterality and more symptomatic (index) knee. Knee symmetry and absolute differences between risk factors for both knees were analyzed. The mean age of 32 patients was 14.6 ± 2.3years. Of the 4 major anatomic risk factors, the most common were trochlear dysplasia in 59/64 (92.1%) knees and patella alta in 51/64 (79.7%) knees. Tibial tubercle lateralization was the least common risk factor being present in 8/64 (12.5%) knees. Of 64 knees, 55 (85.9%) had 2 or more risk factors and 30 (46.8%) had 3 or all 4 risk factors present. There were no significant differences in risk factors based on gender, laterality or index knee. There was symmetry between paired knees for 31/32 (96.8%) patients for trochlear depth, 29/32 (90.6%) for patellar tilt, 27/32 (84.3%) for TT-TG distance and 25/32 (78.1%) for patellar height. There were no significant differences in absolute measurements between knees for any of the risk factors. Patients with bilateral instability had multiple risk factors, with trochlear dysplasia being the most common and increased TT-TG distance being the least common. Majority of patients had 2 or more risk factors and about half had 3 or 4 risk factors in each knee. There was symmetry between paired knees for each risk factorwithout any significant differences between the index knee compared to the contralateral knee. Level III.

Posterior tibial slope correlated with metaphyseal inclination more than metaphyseal height

BackgroundExcessive posterior tibial slope (PTS) is an independent risk factor for anterior cruciate ligament reconstruction (ACLR) failure, but it remains unclear how PTS relates to other proximal tibial morphologic parameters. The purpose of this study was to analyse sagittal tibial metaphysis morphology, and to calculate the correlation coefficients of PTS with anatomical features. MethodsThe authors retrospectively reviewed lateral radiographs of 350 patients that were scheduled to receive primary ACLR to digitize 15 landmarks on the patella, femur, fibula, and tibia, and measure PTS, patellar height, as well as metaphysis height and inclination. Pearson correlation coefficients (r) were computed to assess the linear relationship of PTS with other parameters. ResultsThe PTS was 9.8 ± 3.1° (mid-shaft axis), anterior metaphyseal height and inclination was 30.9 ± 4.6 mm and 33.9 ± 7.2°, and posterior metaphyseal height and inclination was 16.1 ± 4.0 mm and 22.0 ± 5.8°. PTS had a low correlation with anterior (r, 0.225) and posterior metaphyseal heights (r, −0.183). PTS had moderate correlations with anterior (r, 0.385) and posterior metaphysis inclination (r, 0.417). ConclusionPTS has a low correlation with anterior metaphyseal height, but a moderate correlation with anterior and posterior metaphyseal inclination. The moderate correlation between PTS and metaphysis inclination sheds light on the origin of the deformity, and knees with higher PTS are therefore likely to have metaphyses with greater posterior inclinations. The clinical relevance of these findings is that tibial deflexion osteotomy techniques should attempt to address the underlying deformity of excessive PTS by adjusting metaphyseal inclination rather than making diaphyseal resections.

Medial Patellofemoral Complex Reconstruction (Combined Reconstruction of Medial Patellofemoral Ligament and Medial Quadriceps Tendon–Femoral Ligament) With Semitendinosus Autograft Resulted in Similar Clinical and Radiographic Outcomes to Medial Patellofemoral Ligament Reconstruction in Treating Recurrent Patellar Dislocation

PurposeTo compare clinical and radiographic outcomes of medial patellofemoral ligament reconstruction (MPFL-R) and medial patellofemoral complex reconstruction (MPFC-R) for recurrent patellar dislocation. Outcome measures were compared based on the Insall–Salvati index. MethodsPatients who were diagnosed with recurrent patellar dislocation and underwent either MPFL-R or MPFC-R (combined reconstruction of MPFL and medial quadriceps tendon-femoral ligament) were retrospectively analyzed. Group allocation was based on surgical procedure and patient characteristics were collected. Clinical assessments included patient-reported outcome measures (PROMs) and return-to-sports rates. Minimal clinically important difference analysis was performed. A subgroup analysis of PROMs was carried out between patients with an Insall–Salvati index ≤1.2 versus >1.2. The patellar tilt angle, lateral patellar displacement, and bisect offset ratio were measured pre- and postsurgery. Functional failures and complications were assessed. ResultsOverall, 70 patients (72 knees) in the MPFL-R group and 58 patients (61 knees) in the MPFC-R group were included. Patient characteristics were comparable between the groups. At a minimum follow-up of 24 (mean, 50.6 ± 22.1) months, all PROMs were substantially improved (P < .001), without significant intergroup differences. The percentages of patients reaching the minimal clinically important difference were similar after MPFL-R and MPFC-R: 98.6% versus 93.4% (International Knee Documentation Committee), 97.2% versus 98.4% (Lysholm), 98.6% versus 100% (Kujala), and 77.8% versus 72.1% (Tegner). The subgroup analysis based on patellar height and the return-to-sport rates also suggested comparable results. Radiographic evaluation demonstrated significantly smaller lateral patellar displacements (P = .004) and bisect offset ratios (P < .001) but similar patellar tilt angles after MPFC-R. Four (5.6%) patients receiving MPFL-R and 2 (3.3%) patients receiving MPFC-R reported recurrence of functional instability, without statistically significant difference. ConclusionsMPFC-R resulted in similar overall clinical and radiographic outcomes to MPFL-R in treating recurrent patellar dislocation. MPFC-R might not provide additional benefits for patients with an Insall-Salvati index >1.2. Level of EvidenceLevel IV, therapeutic, retrospective cohort study.